Page 1of58 between this versionandtheVersionrecord. Pleasecitethis articleasdoi:10.1002/ana.24551. through thecopyediting, typesetting, paginationandproofreadingprocess, whichmayleadtodifferences This istheauthormanuscript acceptedforpublicationandhasundergone full peerreviewbuthasnotbeen Number of words in the abstract (107), and the body the and in words (107), abstract the Numberof runningandhead: characterstitle the in Number of Melbourne, Melbourne, Victoria, Australia; Australia; Victoria, Melbourne, Melbourne, MD, PhD, MD, ebun, itra Australia; Victoria, Melbourne, Victoria, Australia 3052, FlemingtonParkville, Rd, R The Institute, Research Childrens Murdoch Address Fax+616212 8341 3 Telephone+616235 8341 3 list: Author head: Running Title:

abstract( rm the From Affiliations: Metabolic Unit, Great Ormond Street Hospital, Londo Hospital, Street Ormond Great Unit, Metabolic Un Health, Child of Institute Medicine, Genomic and Email Prof. Thorburn David author: Corresponding Hospita Royal Services, Children's ClinicalGenetic [email protected] :One disorder,more 75 monogenicthan 48774917 3 and David R. Thorburn, PhD David and R. 1 udc Cides eerh nttt, oa Childre Royal Institute, Research Childrens Murdoch Nicole J. Lake, MSc,Lake, J. Nicole

Accepted Article manygenes Leigh One disorder, Syndrome: ) )

This article isprotected by copyright. All rights reserved. 1,2 2

Department of Paediatrics, The University of of University The Paediatrics, of Department Alison G. Compton, PhD, Compton, G. Alison 1,2,4 1

3 Annals ofNeurology Mitochondrial Research Group, Genetics Group, Research Mitochondrial

51 and 35, respectively 35, 51respectively and

l, Melbourne, Victoria, Australia. Australia. l,Victoria, Melbourne, of manuscript including not of n, United Kingdom; Kingdom; United n, iversity College London and and London College iversity oyal Children’s Hospital, 50 50 Hospital, Children’s oyal 1,2 Shamima Rahman, Rahman, Shamima n's Hospital, Hospital, n's causes causes 4 Victorian Victorian Number of figures (3), colour figures (1/3), (1/3), colour figures (3), figures Numberof (1)

Accepted Article

This article isprotected by copyright. All rights reserved. 2 and and Annals ofNeurology John Wiley& Sons tables (3) tables , and supplementary table table and , supplementary Page 2of58 Page 3of58 hntp creain, nihs lae it te m the into gleaned insights correlations, progressive neurodegenerative disorder known as Lei as known disorder neurodegenerative progressive incidences have been observed inpopulatio specific observed been incidenceshave metabolic disorders, with an estimated incidence of incidence estimated an with disorders, metabolic th are generation mitochondrialenergy of Disorders Introduction availableoptions. therapeutic d We diagnosis. for clues provide can that features clinical, associated and syndrome Leigh of etiology the review We basis. etiological its understanding reflecting alone, years 5 last the in characterized t of third a than More nuclear). and (mitochondrial identifie been have 75 than more in hete genetically is disorder neurodegenerative This present pediatric common most the is syndrome Leigh Abstract LS has an estimated prevalence of ~1 per 40,000 liv 40,000 per ~1 of prevalence estimated an has LS ot omn lncl rsnain f mitochondrial of presentation clinical common most n h ls 5 er aoe rfetn hw h intro the how reflecting alone, years 5 last the in dis LS these of 30 Nearly disorder. this underlying highlig identified, been have genes disease 75 than Since the identification of the first pathogenic mu pathogenic the first of identification the Since

Accepted Article

This article isprotected by copyright. All rights reserved. 3 Annals ofNeurology John Wiley& Sons tation in a LS patient in 1991, in patient LS a in tation ease genes have been characterized characterized been have genes ease the significant advances made in in made advances significant the hting the remarkable heterogeneity heterogeneity remarkable the hting iscuss the emergence of genotype of emergence the iscuss at least 1 in 5000 live births. live 5000 in 1 leastat rogeneous, and to date pathogenic pathogenic date to and rogeneous, ns owing to founder mutations. toowing founder ns e most frequent group of inherited of group mostfrequent e neuroradiological and metabolic and neuroradiological ies bohmcl n genetic and biochemical diverse gh syndrome (MIM 25600, LS). LS). 25600, (MIM syndrome gh e births,e duction and greater utility of of utility greater and duction hese disease genes have been been have genes disease hese olecular basis of disease and and disease of basis olecular ation of . disease. mitochondrial of ation d, encoded by two genomes two by encoded d, ies i cide i a is children in disease 2 however much higher higher much however 5 more more 1 The The 3,4

erlgcl eln i L ptet i ascae w associated is patients LS in decline Neurological rsnain a as b mliytmc cric he cardiac, multisystemic; be also can presentation ophthalmological abnormalities including nystagmus including abnormalities ophthalmological hypot regression, and delay developmental deve including Patients development. normal of period initial att my e eetd y R pcrsoy Additio spectroscopy. MR by detected be may lactate im resonance magnetic T2weighted on hyperintensity

a LS as of with annotation the etiologyconsistent re disease, of basis molecular the of understanding ba genetic the characterizing in Advances disorder. genotypephenotype of emergence the enabling genes, pati of identification the has also facilitated MPS i the Beyond disease. of basis genetic the identify has technology (MPS) sequencing parallel massively hrceie h disease. the basal characterize and stem the within symmetrical typically results in death by 3 years of age. yearsof by 3 death in typicallyresults reported. 2 years of age, of years 2 symptomat and death of age onset, of age to respect va significant with heterogeneous, clinically is LS features neuroradiological Clinicaland uua dsucin ae en observed. been have dysfunction tubular 14

6 Acceptedor infection during presenting often symptoms with Article 13,15,16 This article isprotected by copyright. All rights reserved. These lesions are observed as regions of focal focal of regions as observed are lesions These 4 2,7,8,13 912 Annals ofNeurology John Wiley& Sons Progression is often episodic, and and episodic, often is Progression Adultonset LS has been infrequently infrequently been LShas Adultonset ents with mutations in known disease disease mutationsknown in entswith dentification of novel disease genes, disease novel of dentification disorder of energygeneration. disorder of ology. Generally, onset occurs by by occurs onset Generally, ology. sis of LS have consolidated our our consolidated have LS of sis t te eeomn o bilateral of development the ith patic, gastrointestinal and renal renal and gastrointestinal patic, vealing a diverse biochemical biochemical diverse a vealing riation between patients with with patients between riation lop neurological symptoms symptoms neurological lop n otc atrophy. optic and onia, , , and and dystonia, ataxia, onia, relationships for this rare rare this for relationships gn (R) ad elevated and (MRI), aging ganglia structures, which which structures, ganglia transformed our ability to to ability our transformed nal neuroradiological neuroradiological nal illness after an an after illness 2,68 2

The The Page 4of58 Page 5of58 particularly in patients with neuroradiolo with atypical in particularlypatients iceia ivsiain rvdd vdne ht de that evidence provided investigation biochemical ugse ta a eaoi anraiy a te unde the was abnormality metabolic a that suggested e of findings and deficiency, of condition neuropathology the of similarity The 1). (Fig LS of un our to contributed have that milestones research eoe h frt eei mtto ws dniid in identified was genetic first the Before hs srnet rtra a igoi o Leighlike of diagnosis a criteria, stringent these lactate’ CSF or elevated or generation energy a in diagnosis molecular a activity, PDHc or OXPHOS metaboli energy ‘abnormal to (3) criterion amend to CSF lactate indicating abnormal energy metabolism. energy abnormal indicating lactate CSF development motor and intellectual (2) dysfunction, bra of evidence clinical (1) with mus neuroradiology or neuropathology characteristic observed. and involvement matter white as such abnormalities ic Dns eg’ frt ecito o L i 1951 in LS of description first Leigh’s Denis Since etiolog the of of ourunderstanding Thedevelopment OPO) aha, ol cue LS. cause could pathway, (OXPHOS) mitochondrial morphology in tissue tissue muscle skeletal in morphology mitochondrial I) and cytochrome cytochrome and I) NADH:ubiquinon of and (PDHc), complex dehydrogenase 17

Accepted Articlediagn stringent a for criteria defined we 1996, In

c xds (ope I) ihn h oiaie phosphor oxidative the within IV) (complex oxidase

This article isprotected by copyright. All rights reserved. 2123 5 Together with the finding of abnormal abnormal of finding the with Together Annals ofNeurology John Wiley& Sons gy or normal lactate levels. lactate gyor normal derstanding of the etiological basis basis etiological the of derstanding levated lactate and pyruvate and lactate blood levated al delay and (3) elevated serum or or serum elevated (3) and delay al sm indicated by a severe defect in in defect severe a by indicated sm to Wernicke’s , a a encephalopathy, Wernicke’s to from patients, these abnormalities abnormalities these patients, from 1991, 2 t be accompanied by progressive progressive by accompanied be t syndrome can be considered, considered, be can syndrome In 2015, it would seem prudent prudent seem would it 2015, In , . Where patients do not fulfill fulfill not do patients Where . 18 may also be be also may atrophy cerebral related to mitochondrial mitochondrial to related gene instem and or ganglia basal or and instem ical basis of Leigh syndrome Leigh syndrome basis of ical there have been several key key several been have there lig ies etiology. disease rlying iiny f h pyruvate the of ficiency e (complex (complex oxidoreductase e 5 40 years of clinical and and clinical of years 40 osis of LS, requiring that requiring LS, of osis 2

ylation ylation 19,20

patients (Table 1 (Table patients rtis eurd o ter seby saiiy and stability assembly, their for required To date, pathogenic mutations in more than 75 genes 75 than more in mutations pathogenic date, To Leighsyndrome of basis Theheterogeneous genetic LS. of diagnosis support clinical a bioche a of evidence provide to undertaken often is frequently observed, whereas defects of complexes I complexes of defects whereas frequentlyobserved, mult and deficiency IV complex Isolated deficiency. g disease LS all of third a nearly with LS of cause deficiency I Complex generation. energy of disorder PDH hence OXPHOS; for donors electron of generation carrier coenzyme Q coenzyme carrier OX the five of each in defects Biochemical (Fig2). t in located complexes multi five comprises tra proton transfer, electron of pathway OXPHOS The pat broader or OXPHOS to directly linked mostly LS, e other multiple that established been since has It mitochondrial a as LSreannotated Subsequently was rare. hs dsae ee ecd srcua cmoet of components structural encode genes disease these mitochondrial defective of theme common a suggested maternal (for mutations in mitochondrial DNA, mtDNA DNA, mitochondrial in mutations (for maternal possible several are there diseases, mitochondrial 2,6,7 Measurement of OXPHOS and PDHc in a patien a in enzymes PDHc and OXPHOS of Measurement

Acceptedinfor detailed more for 1 Table Supplementary see , Article

10 (CoQ 10 This article isprotected by copyright. All rights reserved. ), have been observed in LS patients. PDHc enables PDHc patients. LS in observed been have ), 6 Annals ofNeurology John Wiley& Sons nzymatic deficiencies can underlie underlie can deficiencies nzymatic ciiy A i te ae o other for case the is As activity. PHOS complexes, and the electron electron the and complexes,PHOS he mitochondrial inner membrane inner mitochondrial he mical defect in these pathways to to pathways these in defect mical is the most common biochemical biochemical common most the is I, III, V or of CoQ of or V III, I, modes of inheritance including including inheritance of modes encephalopathy. encephalopathy. have been identified in affected affected in identified been have enes associated with complex I I complex with associated enes pe XHS eet ae also are defects OXPHOS iple the OXPHOS complexes, or or complexes, OXPHOS the c deficiency also represents a represents also deficiency c wy o eeg generation. energy of hways ) and autosomal recessive or or recessive autosomal and ) sot ad T synthesis ATP and nsport, nry metabolism. energy t biopsy or cell line cell or biopsy t mation 10 are relativelyare ). Most of of Most ). the 22

Page 6of58 Page 7of58 frequently with associated cerebral atrophy. cerebral associated with frequently ped cerebral the to down extending often cases, all symmet bilateral included infants these in features than later no and life of months 8 first the within experienc presentation, LS characteristic a display dfcec i te edn bohmcl ai o LS of basis biochemical leading the is deficiency I ae reported. cases Iass complex of cause recessive autosomal frequent (NDU 4 protein FeSulfur (Ubiquinone) Dehydrogenase complex of presentation clinical frequent most The I Complex deficiency mt caused by syndrome LeighLeighlike typesand of ca genetic nuclearencoded common more the on focus available (where options therapeutic and diagnosis, bio and clinical associated etiologies, genetic and discus to rather but syndrome, Leighlike and Leigh indep an provide to not is article this of aim The identified tomore be diseasegenes therestill are ge a without remain patients LS many genes, disease r the Despite genes). nuclearencoded (for Xlinked may be associated with heterogeneous . Pa phenotypes. heterogeneous with associated be may nucleare other in mutations to contrast in LS, had cases also had hypertrophic cardiomyopathy. cardiomyopathy. hypertrophic cases had also

24

Accepted with reported patients all almost Interestingly, Article

This article isprotected by copyright. All rights reserved. 7 24,25 Annals ofNeurology John Wiley& Sons Approximately a third of all reported reported all of third a Approximately . . rical basal ganglia lesions in almost almost in lesions ganglia basal rical ncoded complex I subunits, which subunits, I complex ncoded I deficiency is LS, is deficiency I th review of all known forms of of forms known all of review th emarkable number of established established of number emarkable n ost n dms typically demise and onset ing s the most relevant biochemical biochemical relevant most the s , summarized in Table 2). We We 2). Table in summarized , DNA mutations. DNA 30 months. Neuroradiological Neuroradiological months. 30 chemical features relevant for for relevant features chemical uncles, pons and medulla, and and medulla, and pons uncles, ociated LS, with more than 20 20 than more with LS, ociated netic diagnosis, indicating that that indicating diagnosis, netic tients with tients . 2,6,7 uses, as well as describing describing as well as uses, S) uui ae h most the are subunit FS4) uain i te NADH the in Mutations NDUFS4 NDUFS4 24 and complex complex and mutations mutations be associated with an early age of death, with all all with death, of age early an with associated be NDUFS1 NDUFS4 patients with LS and CoQand LS with patients S ih ai demise, rapid with LS Deficiencies of complex II, complex III or CoQ or III complex II, complex of Deficiencies normal school life’. normalschool of preservation years, childhood late into survival and collectively underlie fewer than 10% of allcas of 10% than fewer underlie collectively and uui SH wr te is ncer uain ident mutations disease. nuclear first the were SDHA subunit ots n scubn b 4 years. 4 by succumbing and months supplementation and survive into adulthood,into survive and supplementation Flavop (Ubiquinone) Dehydrogenase NADH in Mutations observed. died in early childhood, although a few cases were were cases few a although childhood, early in died factor TTC19 develop neuroimaging abnormalities con abnormalities neuroimaging develop TTC19 factor alleles of of alleles have patients no alleles, lossoffunction complete hs ugop f S s meaie sne hs pati these since imperative, is LS of subgroup this forms of the disease. While all reported reported all While disease. the of forms Complex II, Complex III and Coenzyme Q Coenzyme and III Complex II, Complex with life. mayincompatible be 29 have also been widely reported to cause LS. cause to reported widely been also have , Some patients with patients Some 33 NDUFV1 n rpr dsrbd mrvmn o hptc u no but hepatic of improvement described report One Accepted ArticleNDUFV1-

28,30 or or

and 29 Nearly all patients with mutations in the complex complex mutationsthe in with Nearlyall patients NDUFS1 u ohr ains a eprec a id S course LS mild a experience may patients other but 10 10 NDUFS1 deficiency have been reported. been have deficiency This article isprotected by copyright. All rights reserved. SDHA , suggesting that complete loss of these two protei two these of loss complete that suggesting , mutations have a severe infantile presentation of of presentation infantile severe a have mutations mediated LS appear to be particularly severe severe particularly be to appear LS mediated 24 Most patients with with patients Most 8 32 NDUFS4 Annals ofNeurology 10 John Wiley& Sons although this has not been consistently consistently been not has this although deficiencies deficiencies 10 (ubiquinone) are rare causes of LS, of causes rare are (ubiquinone) es. reported patients presenting by 8.5 8.5 by presenting patients reported cognitive abilities and an ‘almost ‘almost an and abilities cognitive alive in late childhood. late in alive been described with two null null two with described been 2,6,28 mutations except one predict predict one except mutations NDUFS1 ns a rsod o CoQ to respond may ents sistent with LS. with sistent Mutations in the complex II II complex the in Mutations fe t cue OXPHOS cause to ified 9,32 NDUFV1 oen ( 1 rotein Prompt recognition of of recognition Prompt mutations appear to to appear mutations mutations also also mutations NDUFV1 t neurological neurological t 31 III assembly IIIassembly Occasional Occasional 26,27 Thus, Thus, , with with , ) and and ) ns ns 10 Page 8of58 Page 9of58 RP CLRPPR LRPPRC LRPPRC rsnain soitd ih UF deficiency. SURF1 with associated presentation population. ainsrvae mda g fdaha . year 5.4 at death of age median a revealed patients not respond to treatment.tonotrespond with infcnl t mortality. to significantly de metabolic acute of episodes by punctuated course dysmorphism, mild facial 220111) include MIM (LSFC, recently been recognized, including deficiency of A of deficiency including recognized, been recently a posttranscriptional mitochondrial on dysfunction etrs uh s ekdsrpy n atrophy. and as such features incidence of LSFC of ~1 in 2000 live births (Table (Table births live 2000 in ~1 of LSFC of incidence 200 cases described to date in the literature. the in date to described cases 200 rep frequently most the of one are and LS deficient most the are factor, assembly IV complex a encoding

symptoms, SURF1 SURF1 complex IV disease genes disease complexIV ope I dfcec udris 1% f S cases. LS of ~15% underlies deficiency IV Complex deficiency IV Complex SURF1 SURF1 patient cohort highlighted the relatively homogeno relatively the highlighted cohort patient ascae L ta i osre fr S ains due patients LS for observed is than LS associated .34 mutations, p.A354V 34 uain wr oiial rpre i a ioae F isolated an in reported originally were mutations 37,40

and another patient with CoQwith patient another and mutations lack the neuroradiological hallmarks of L of hallmarks neuroradiological the lack mutations

Accepted F with associated features clinical Characteristic Article 9

3,37

SCO2 itie f 6 eotd ae ihrtd homozygo inherited cases reported 56 of Fiftyfive This article isprotected by copyright. All rights reserved. 37 , , elcig fudr fet ht a rsle i a in resulted has that effect founder a reflecting LRPPRC 9 10 10 , and and , Annals ofNeurology deficient LS due to due LS deficient 35 John Wiley& Sons Our recent natural history study of a of study history natural recent Our 35,36 ETHE1 35 Survival analysis of 142 142 of analysis Survival orted causes of LS, with more than than more with LS, of causes orted oee, mnrt o patients of minority a However, TP synthase. TP s, 3). nd translation processes have have processes translation nd common cause of complex IV IV complex of cause common 35 . 3 compensation that contribute contribute that compensation indicating longer survival in in survival longer indicating liver pathology and a clinical a and pathology liver 3739 Broader effects of LRPPRC LRPPRC of effects Broader 2,6,7 us clinical and biochemical biochemical and clinical us

Mutations in in Mutations to mutations in other other in mutations to PDSS2 41 ecaain LS renchCanadian Despite presenting presenting Despite S or show atypical show or S renchCanadian renchCanadian mutations did mutations SURF1 SURF1 us us n n , ,

rsnain ht eebe L ciial ad neuro and clinically LS resembles that presentation rdmnn cue o L ascae wt mDA depl mtDNA with associated LS of causes predominant NDUFA4 pathogene the deficiency, IV complex isolated an as neuroradiological improvement in patients with with in improvementpatients neuroradiological resulte accumulation sulfide reduce that strategies ( been have translation defective or depletion mtDNA disea various in mutations Thus, deficiency. OXPHOS or replication mtDNA impairs that defect molecular comple of components structural encodes mtDNA Since deficiencies OXPHOS Combined , learning difficulties and survival into a into and survival epilepsy,learning difficulties uain in Mutations mit of globala to defect attributable therefore be SUCLA2 subunit NDUFA4, which was previously thought to be be to thought previously was which NDUFA4, subunit causing mutations with subunit IV complex only The h cneso o sciyo t sciae within succinate to succinylCoA of conversion the eiiny s cneune f ufd accumulation sulfide of consequence a is asso deficiency the whereby toxicity, sulfide of manifestation det sulfide in ETHE1 for role a of characterization Table 1, see Supplementary Table 1A for more detail more for 1A Table Supplementary see 1, Table or or mutations have been reported to cause childhoodon cause to reported been have mutations SUCLG1

Accepted ArticleETHE1

, encoding subunits of succinylCoA synthetase whic synthetase succinylCoA of subunits encoding , as ehlaoi ecpaoah (E (I 602473 (MIM (EE) encephalopathy ethylmalonic cause

This article isprotected by copyright. All rights reserved. 10 10 Annals ofNeurology John Wiley& Sons ETHE1 dulthood. ochondrial translation. translation. ochondrial d in clinical, biochemical and and biochemical clinical, in d translation can cause combined combined cause can translation sis of of sis identified in patients with LS LS with patients in identified ed informationTable 1A informationTable ed xfcto rvae E a a as EE revealed oxification mutations. LS is the recently reassigned reassigned recently the is LS itd sltd ope IV complex isolated ciated . 43 45 Accordingly, therapeutic therapeutic Accordingly,

se genes associated with with associated genes se e I II I ad , a V, and IV III, I, xes a subunit of complex I. I. complex of subunit a LRPPRC LRPPRC radiologically. etion are mutations in in mutations are etion the . cycle. acid citric the set LS with prominent prominent with LS set 44

uain may mutations h catalyzes catalyzes h 38,42 The The ). The The ). , a ), Page 10of58 Page 11of58 patients. ula ecdd ttN mdfig nye ae requi are enzymes modifying mttRNA encoded Nuclear ouain Tbe 3). (Table population patients. with account to hypothesized been has supply, nucleotide i involved an kinase, diphosphate nucleoside ee ntal ietfe i to neae L patie “MitoExome”, the of LS sequencing unrelated two in identified initially were th sc in to used be can and succinylCoA, of accumulation observed frequently is aciduria Methylmalonic

ls o L dsae ee. iohnra methionyl Mitochondrial ( genes. disease LS of class p these in mutations and translation, mitochondrial wn t a one efc, ih n siae L inc LS estimated an with effect, founder a to owing SUCLA2 significant proportion of LS within thisLS population within of significantproportion popu European the in 100 in ~1 of frequency carrier SUCLG1 no eng yas n yug adulthood. young and years teenage into involvement (involvement MTFMT SUCLA2 46,47 51 .3+GA uain a a ih are feuny i frequency carrier high a has mutation c.534+1G>A and ) was the first LS disease gene of this type to thisbe type of gene disease LS firstthe ) was Most cases carry at least one copy of the c.626C>T the of copy one least at carry cases Most ypos eeal peet n al ifny ad p and infancy, early in present generally Symptoms and and SUCLG1

Accepted ArticleSUCLA2

SUCLG1

) or deafness (more common with with common (more deafness or ) 4 n neato bten ucnlCA yteae and synthetase succinylCoA between interaction An aiet iial, hy a b dfeetae by differentiated be can they similarly, manifest mutations. This article isprotected by copyright. All rights reserved. 50 and subsequently identified in multiple other LS other multiple in identified subsequently and 46

11 11 48,49 Annals ofNeurology John Wiley& Sons Although patients with mutations in in mutations with patients Although . 51 roteins represent a relatively new new relatively a represent roteins

for mtDNA depletion in patients patients in depletion mtDNA for lation and so may account for a for account may so and lation reen for these two defects in LS LS in defects two these for reen nts through targeted exome exome targeted through nts dne f i 10 i that in 1700 in 1 of idence reported. reported. n regulating mitochondrial mitochondrial regulating n SUCLA2 ese patients due to an an to due patients ese tRNA formyltransferase formyltransferase tRNA mutation, which has a a has which mutation, n the Faroe Islands Islands Faroe the n atients can survive survive can atients e fr efficient for red MTFMT mutations). mutations mutations 49 The The liver

ains ar ete the either carry patients ecnae f tN mlcls ht ar te pathog the carry that molecules mtDNA of percentage uain wih ee mn te is L mttos d mutations LS first the among were which mutation, cases.LS of mutations mtDNA that suggested have studies Cohort defici OXPHOS combined and V Complex I,IV, Complex Leighsyndrome mutations causing DNA Mitochondrial , r n iohnra tNs Tbe 1 (Table tRNAs mitochondrial in or V, e genes in majority the with LS, cause to described adulthood. hav patients where brain, including tissues in <50% caus to propensity their for notable are deficiency detailed informationA detailed Mutations in complex I subunits MTND3 and MTND5and MTND3 subunits I complex in Mutations mutant loads of of loads mutant i LS disease, mitochondrial of manifestation severe determinant important an is heteroplasmy, of level ee r etmtd o nele 1% f l L cases LS all of ~10% underlie to estimated are gene Vmed complex of basis genetic established only the including the wellknown m.3243A>G m.3243A>G wellknown iden the been including have mttRNAs five in mutations uncommon, MTATP6 n srkie psds MLS ad aenly inh maternally and (MELAS) episodes like and ence mitochondrial of syndromes the with associated , are the most frequent mtDNA causes of LS. of causes mtDNA frequent most the are 5254 2,6,7

Accepted Articleg mtDNAencoded 37 the of 13 in mutations date, To ≥

0, although 90%,

). LS can also be caused by largescale mtDNA delet mtDNA largescale by caused be also can LS ). MTATP6 MTATP6 This article isprotected by copyright. All rights reserved. MTND5 m.8993T>G or the less severe m.8993T>C m.8993T>C severe less the or m.8993T>G 12 12 MTTL1 se upeetr Tbe A o more for 1A Table Supplementary see , Annals ofNeurology mutations associated with complex I I complex with associated mutations John Wiley& Sons mutation that is more commonly commonly more is that mutation e LS even when the mutant load is is load mutant the when even LS e ncoding subunits of complexes I or or complexes I of subunits ncoding of the clinical presentation. As a As presentation. clinical the of s typically associated with high high with associated typically s e been observed to survive into into survive to observed been e underlie approximately 1020% 1020% underlieapproximately iated LS, and mutations in this this in mutations and LS, iated phalopathy with acidosis lactic with phalopathy , , . and in the complex V subunit V complex the in and MTATP6 nc uain kon s the as known mutation, enic 2,6,7,55 rtd ibts n deafness and diabetes erited associated with Complex with associated encies encies The majority of these these of majority The escribed. tified in LS patients, patients, LS in tified mutations represent mutations enes have been been have enes 56,57 Although Although ions. 2 The The Page 12of58 Page 13of58 LIAS pyrophosphate (TPP) have more recently been describ been recently more have (TPP) pyrophosphate mutations. prxmtl eul ubr o by ad il ae d are girls and boys of numbers equal approximately in m.8344A>G the and (MIDD), can be challenging. be can diagnosis biochemical the that means Xinactivation wil cells of ~50% typically that means inactivation ragged red fibers (MERRF). raggedfibers red observations thatobservations finding. cor the of agenesis with patients, LS in deficiency lactate:pyruvat a and pyruvate elevated of Evidence deficiency complex dehydrogenase Pyruvate uain i gns eae t te Dc ofcos l cofactors PDHc the to related genes in Mutations as o PHsoitd LS. PDHcassociated of cause o ta mutation. that for i members family other in load mutant heteroplasmic diseas mtDNA suggesting history family maternal any patien many maternally, inherited is mtDNA Although the mother and other maternalrelatives. other mothertheand in heteroplasmy of levels high at present mutation genes encode enzymes responsible for synthesis and synthesis for responsible enzymes encode genes 62 Mutations in in Mutations 62

Acceptedsurprising not is inheritance pseudodominant This Article PDHA1

e novo De 64 Cohort studies of PDHc deficient individuals suppo individuals deficient PDHc of studies Cohort PDHA1 likely a has high mutations in mtDNA are also relatively common, so so common, relatively also are mtDNA in mutations 58,59 This article isprotected by copyright. All rights reserved. , encoding the E1 alpha subunit, are the predominan the are subunit, alpha E1 the encoding ,

MTTK MTTK 62,63

60,61 PDHA1 that typically causes with with epilepsy myoclonic causes typically that 13 13 de novo de

Annals ofNeurology John Wiley& Sons is an X gene, but but gene, Xchromosome an is l express the mutant allele. Skewed Skewed allele. mutant the express l mutation rate. mutation the proband can be undetectable in in undetectable be can proband the e ratio of <20 can indicate PDHc PDHc indicate can <20 of ratio e s below the pathogenic threshold threshold pathogenic the below s of PDHc deficiency in females females in deficiency PDHc of u clou aohr common another callosum pus ed to cause LS. The The LS. cause to ed ts with mtDNA mutations lack lack mutations mtDNA with ts . hs a b bcue the because be can This e. transfer of the lipoic acid acid lipoic the of transfer pi ai ad thiamine and acid ipoic ansd with iagnosed given that random X random that given 62,63

rt previous previous rt LIPT1 PDHA1 and a t t

present with a recognizable metabolic profile that profile metabolic recognizable a with present rsnain r course. or presentation iutnosy ipa nuoailgcl n clinic syndromes, and neuroradiological display simultaneously LS/MELAS a of presentation clinical rare a underlie ee ascae wt LS. with associated genes are cases many and , mitochondrial ketoglutarate dehydrogenase and branchedchain branchedchain and dehydrogenase ketoglutarate eyrgns. ains ih Dc eiiny u to due deficiency PDHc with Patients dehydrogenase. the and , h asne f TPP. of absence the when identifiable be may but assays, enzymatic PDHc erptooy r errdooy bt a as refl also can but neuroradiology, or neuropathology t refers usually syndrome Leighlike of diagnosis A Leighlike with syndrome associated Disease genes SLC19A3 ‘treatable’ or ‘reversible’ LS. ‘treatable’ ‘reversible’ or PDHc deficiency due to mutations in genes associate genes in mutations to due deficiency PDHc course. when particularly biotin, dose high and thiamine of imp neuroradiological and clinical significant show eriaig n eioi decline. ence episodic and progressive neuroimaging a as LS phenocopies which 607483), gan basal biotin/thiamineresponsive cause to known 71 ned ains with patients Indeed and 36,73 SLC25A19

while largescale mtDNA deletions can cause Pearso cause can deletions mtDNA largescale while Accepted Article

DLD 68,69 2 egie rsnain cn ipa oelp with overlap display can presentations Leighlike Mutations in the thiamine transporter transporter thiamine the in Mutations gene encodes the PDHc subunit E3 dihydrolipoamide dihydrolipoamide E3 subunit PDHc the encodes gene ) can be missed because of the presence of TPP in r in TPP of presence the of because missed be can ) MTND5 71,72 This article isprotected by copyright. All rights reserved.

SLC19A3 and 70 Unlike typical LS, patients with BTBGD can can BTBGD with patients LS, typical Unlike 14 14 MTND3 uain hv be dsrbd with described been have mutations Annals ofNeurology John Wiley& Sons

reflects additional deficiency of of deficiency additional reflects mutations have been described to to described been have mutations rovement following administration administration following rovement o patients presenting with atypical atypical with presenting patients o overlap syndrome where patients patients where overlap syndrome commenced early in the disease disease the in early commenced ⍺ caused by mutations in the same same the in mutations by caused d with TPP availability ( availability TPP with d kt ai dehydrogenase. acid keto la ies (TG) (MIM (BTBGD) disease glia esrn PH ciiy in activity PDHc measuring l hrceitc o both of characteristics al uain i tee genes these in mutations ect an atypical clinical clinical atypical an ect phalopathy with similar similar with phalopathy SLC19A3 n syndrome with with syndrome n are well well are TPK1 outine outine other other 6567 6567 ⍺ , , Page 14of58 Page 15of58 ains o ms dsae ee. However genes. disease most for patients ains ih uain in mutations with patients NDUFS4 NDUFS4 include fit not may that presentation Leighlike a underlie neuropathology. Leighlike syndromes and hepatic dysfunction is present. is dysfunction hepatic and syndromes f exhibits neuropathology the where LS, and 203700) Alper between spectrum a on lie generally mutations ol nt e dniid mn L patients, LS among identified be not could molecul a between correlations strong Historically, relationships genotypephenotype Theemergenceof combined OXPHOS enzyme deficiency. enzyme OXPHOS combined ass (MEGDEL) syndrome Leighlike and encephalopathy neuroradiology, or with unusual additional symptoms additional with unusual orneuroradiology, n lnt o dsae ore cn e bevd (illu observed be can course, disease of length and where courses, disease distinct underlie can genes characteristi having Beyond basis. genetic specific the of knowledge and deficiency biochemical a with s these of presence The examples). for 3 Table (see emerging of recognition the enabling gene, same the mu of identification the facilitated has technology xeine al ost u a oe aibe lifespan variable more adolescence. a but onset early experience SERAC1

Accepted onset early with associated be to appear mutations Article hc cue 3mtyguaoi aiui wt deaf with aciduria 3methylglutaconic causes which

74,75 SUCLA2 This article isprotected by copyright. All rights reserved. utemr, egie ains with patients Leighlike Furthermore, or the complex IV assembly factor PET100 PET100 factor assembly IV complex the or 78 15 15 These patients often present with atypical atypical with present often patients These Annals ofNeurology 2 John Wiley& Sons in part reflecting the low numbers of of numbers low the reflecting part in

76,77 the increasing utilization of MPS MPS of utilization increasing the ltiple LS patients with mutations in in mutations with patients LS ltiple differences in median age of onset, of age median in differences Disease genes that predominantly predominantly that genes Disease c symptoms, different LS disease disease LS different symptoms, c genotypephenotype correlations correlations genotypephenotype ignature features in combination combination in features ignature patient’s ethnicity may suggest a suggest may ethnicity patient’s including abnormal behavior. abnormal including strated in Fig 3). For example, example, For 3). Fig in strated a stringent LS diagnosis also also diagnosis LS stringent a sHuttenlocher syndrome (MIM (MIM syndrome sHuttenlocher ar defect and clinical features features clinical and defect ar aue caatrsi o both of characteristic eatures including survival into into survival including ociated with isolated or or isolated with ociated and death, whereas whereas death, and POLG POLG ness, 79

ahgnss gvn h rmral dvre ag of range diverse remarkably the given pathogenesis, ahgnss f S ( LS of pathogenesis and cofactors required for enzyme activity ( activity enzyme for required cofactors and expressi and maintenance mtDNA of complexes, stabil OXPHOS activity, catalytic of defects include These that the specific enzyme or process that is disrupt is that process or enzyme specific the that L pa to key the of being generation energy mitochondrial basis genetic the of understanding current Our dis common indicate defects a molecularEstablished 2). in mutations(outlined Table treatment to responsive most are that forms genetic lif enable can cases some in and options, treatment disea of basis biochemical or genetic the recognize th to responses or and function, levels, expression ti reflect part in to expected be may they although molecula the determine to required is research More genotyp LS more reveal may phenotyping thorough and est an with patients additional of accumulation The nomtoTbe 1BinformationTable new raises activity PDHc or OXPHOS in role Accepted direct a ar that genes disease several of identification The 1A informationTable more detailed Article

). Some of these defects appear to cause secondary secondary cause to appear defects these of Some ). al 1 se upeetr Tbe B o mr detail more for 1B Table Supplementary see 1, Table

This article isprotected by copyright. All rights reserved. ). 16 16 Table 1, see Supplementary Table 1A for for 1A Table Supplementary see 1, Table Annals ofNeurology John Wiley& Sons e not known to encode proteins with proteins encode to known not e se has important utility for guiding for utility important has se d snta eeat o molecular to relevant as not is ed ablished genetic basis of disease of basis genetic ablished e genetic defect. Being able to to able Being defect. genetic e thogenesis. However, it appears appears it However, thogenesis. ity or assembly of individual individual of assembly or ity ssuespecific effects relating to to relating effects ssuespecific molecular defects causing LS. LS. causing defects molecular r basis of such relationships, relationships, such of basis r aig nevnin o the for intervention esaving order of energy generation energy orderof such as as such S supports impairment in in impairment supports S ephenotype correlations. correlations. ephenotype on, and of PDHc activity PDHc of and on, usin aot the about questions SLC19A3 defects of of defects or or BTD ed ed

Page 16of58 Page 17of58 brain increase during infancy and peak in early chi early in peak and infancy during increase brain ETHE1 biotinidase deficiency due to due biotinidasedeficiency produce substrates for the citric acid cycle,acid citric the for substrates produce inhibition from animal and cellular models.cellular and animalinhibition from variability tissues. show may which enzymes, OXPHOS or PDHc membrane. stab the reducing by OXPHOS impair may AIFM1 factor SE protein remodeling the in Mutations ~20–25% of resting energy expenditure in adults. in expenditure restingenergy of ~20–25% LS. of pathogenesis the to supply energy diminished fur metabolism energy cerebral of understanding Our of thecause to development sufficienttherefore be mito on effect indirect an mutation, of consequence contribution of primary effects of these disorders disorders these . of effects primary of contribution pathogenes to this of relevance the However OXPHOS. PDHc activity remains to be determined. These enzym These determined. be to remains activity PDHc and recycli biotin HIBCH) (ECHS1, catabolism valine OXPHOS and PDHc activity, PDHc and OXPHOS suggested to be the mechanism by which which by mechanism the be to suggested as LS (Table 2), (Table LS as 78,8082 uain dsrbd above. described mutations 78,82 80,81 uh eodr dfcs ae o be rpre i p in reported been not have defects secondary Such

However, the mechanism by which mutations in enzym in mutations which by mechanism the However, nta, n cuuain f oi ratv metabol reactive toxic of accumulation an Instead,

Accepted Article83,84

lhuh hr i eiec fAPdfcec ad c and deficiency ATP of evidence is there although

This article isprotected by copyright. All rights reserved. BTD 81,88 similar to the toxic accumulation of sulfide due t due sulfide of accumulation toxic the to similar mutations, a treatable condition which can manifes can which condition mutations,treatable a 43 Although it may not be the primary primary the be not may it Although 17 17 85,86 81,87 Annals ofNeurology John Wiley& Sons ECHS1

an important source of electrons for for electrons of source important an 89 LS. LS. The metabolic requirements of the of requirements metabolic The ldhood, where it uses at a a at glucose uses it where ldhood, ther supports the central role of a of centralrole the ther supports chondrial energy generation can can generation energy chondrial and and Brain metabolism accounts for accounts metabolism Brain ng (BTD) impair OXPHOS and OXPHOS impair (BTD) ng RAC1 and apoptosisinducing apoptosisinducing and RAC1 es facilitate pathways that can can that pathways facilitate es uh s etre valine perturbed as such HIBCH lt o te mitochondrial the of ility s s nla, s s the is as unclear, is is across patients and and patients across mutations impair impair mutations ites has been been has ites es involved in in involved es atients with with atients mlx IV omplex o o t LS, including in infancy and early childhood,early and infancy in including LS, neuropatholo develop to disorders generation energy observed in patients after the age of 7, of age the after patients in observed supported by the cohort study of of study cohort the by supported childh late beyond and into span life a predict may vulnerabili increased of periods past survival that metabolism. resting body’s the of 66% to up of rate nldn bten ifrn ban regions, brain different between including pathogenes to contribute protein mitochondrial in differences demonstrating must supply energy reduced otiue o ahgnss Ti i spotd y tr by supported is en This pathogenesis. to mitochondrial contribute of defect molecular a to responses ht eet i OPO ad nry eeain a ca age of years ~5 at can highest are requirements generation indica energy Studies LS. of form and the in neurodegeneration OXPHOS in defects that metabolism. st brain examined all of requirement energy highest ganglia/thal basal and the that suggested g for rate metabolic cerebral the examining studies Po unexplained. is patients LS a in ganglia neurodegeneration basal the of vulnerability particular The either de of age median the to relative report last at age PET100

91 utemr te aaiy o ptet wt inherit with patients for capacity the Furthermore , ,

Accepted ArticleNDUFV1 or MTFMT This article isprotected by copyright. All rights reserved. LRPPRC mutations in Figure 3. 3. mutationsFigure in 37 adsgetdb h oal ae median later notably the by suggested and 18 18 patients, where no metabolic crises were were crises metabolic no where patients, 90 Annals ofNeurology 93 are relevant to observations suggesting suggesting observations to relevant are John Wiley& Sons 92 imply that cell and tissuespecific tissuespecific and cell that imply suggests that other factors beyond a beyond factors other that suggests ty in infancy and early childhood childhood early and infancy in ty t osre ars ptet with patients across observed ath amus do not necessarily have the have necessarily not do amus anscriptomic studies of cells and and cells of studies anscriptomic ood for patients with LS. This is is This LS. with patients for ood expression across mouse tissues, tissues, mouse across expression gical abnormalities distinct from from distinct abnormalities gical 90 ructures in conditions of basal basal of conditions in ructures uoe n nat ad children and infants in lucose ig ht h bans metabolic brain’s the that ting Therefore it is not surprising not is it Therefore nd brain stem structures to to structures stem brain nd sitron emission tomography tomography emission sitron ergy generation will also also will generation ergy is. Previous studies studies Previous is. use early onset onset early use ed mitochondrial mitochondrial ed Page 18of58 Page 19of58 perhaps a few hundred genes is a popular approach, approach, popular a is genes hundred few a perhaps but in our experience they can enable molecular dia molecular enable can they experience our in but y sprt ts fr tN mttos Woe genom Whole mutations. mtDNA for test separate a by transcriptionaldysregulation. demonst patients disease mitochondrial from tissues first, in order to potentially avoid the need for m for need the avoid potentially to order in first, is paradigm diagnostic the diagnosis, for required enzym While analysis. genebygene subsequent guide respe fibroblasts skin cultured and biopsy muscle a OXPHOS measure to been traditionally has step next typically is not a sensitive test for mtDNA mutatiomtDNA for test sensitive a not is typically mutat detect potentially can sequencing exome Whole beco can panels such that means genes disease novel magnetic resonance spectroscopy) spectroscopy) resonance magnetic blo in acid lactic as such parameters laboratory of multio of extent determining including examination Detailed approaches to diagnosis of Leigh syndrome Leigh of diagnosis to approaches Detailed etiologies k new incorporate to strategies diagnostic Updating 18,55 with and relative cognitive sparing sparing cognitive relative and hypertrichosis with the phenotype may prompt investigation of a specifi a of investigation prompt may phenotype the sequencing. Each of these approaches has specific a specific has approaches these of Each sequencing. w less is but genes, mtDNA and nuclear in mutations

Accepted Article f and medical detailed a remain steps initial The .

94 This article isprotected by copyright. All rights reserved.

18 . In patients such as those described in Table 3, 3, Table in described those as such patients In . 19 19 Annals ofNeurology John Wiley& Sons uscle biopsy. Testing gene panels of of panels gene Testing biopsy. uscle od and CSF, and imaging (MRI and and (MRI imaging and CSF, and od ns, so may need to be accompanied accompanied be to may need so ns, increasingly shifting to using MPS MPS using to shifting increasingly 35 gnosis of LS in more than 60% of of 60% than more in LS of gnosis dvantages and disadvantages disadvantages and dvantages c gene, such as such gene, c ctively, the results of which can can which of results the ctively, although the rate of discovery of of discovery of rate the although rating tissuespecific patterns of of patterns tissuespecific rating Hwvr n ot ains the patients most in However, . rgan involvement, measurement involvement, rgan have been published elsewhere elsewhere published been have and PDHc enzyme activities in in activities enzyme PDHc and ions in any but but gene nuclear any in ions e testing may often still be be still often may testing e e udtd ut quickly. quite outdated me idely available than exome exome than available idely nowledge of molecular molecular of nowledge sqecn cn detect can sequencing e amily history, physical physical history, amily SURF1 in a child child a in 95

96

patients with a stringent LS diagnosis, as defined defined as diagnosis, LS stringent a with patients primarily mediated by effects on pathways responsib pathways on effects by mediated primarily rti metabolism. protein production of reactive oxygen species (ROS). Increa (ROS). species oxygen reactive of production

al ucin hog mcaim dsic fo eeg ge energy from distinct mechanisms through function furthermor may OXPHOS and PDHc of defects Molecular maycontribut additionally morphology mitochondrial complex I activity in in activity I complex improve significantly but modestly to observed was mito in improvement recently, More pathogenesis. to ellr rwh mTORC1. growth cellular exp the on effects including availability, nutrient eosrtd ht Dc n OPO dfcs a induc can defects includi pathways cellular multiple OXPHOS of dysregulation and PDHc that demonstrated ge energy mitochondrial of disorders in dysfunction the supporting evidence of body growing a is There intervention emer an dysfunction: cellular broader into Insights ellr oes f Dc n OPO ezm deficienc enzyme OXPHOS and PDHc of models cellular enviro cellular a produce can defects enzyme OXPHOS improved lifespan and attenuated neurodegeneration neurodegeneration attenuated and lifespan improved model of LS, of model 2 . . 97 Acceptedthese of dysregulation that notion the supporting Article

94 hs dsubne i clua mtbls apa t appear metabolism cellular in disturbances These Ndufs4 94 ramn wt rpmcn a ihbtr f mTORC1, of inhibitor an rapamycin, with Treatment This article isprotected by copyright. All rights reserved. ncot mice, knockout 20 20 Annals ofNeurology John Wiley& Sons by the original criteria of Rahman et Rahman of criteria original the by ression and activity of regulator of of regulator of activity and ression g hs ta rglt RA and RNA regulate that those ng 98 motor performance, lifespan and lifespan performance, motor le for sensing and responding to to responding and sensing for le sed ROS have been observed in in observed been have ROS sed e to disease pathology. diseasepathology. to e contribution of broader cellular broader of contribution suggesting that effects on on effects that suggesting n the in neration. Recent studies have have studies Recent neration. chondrial cristae morphology morphology cristae chondrial nment more conducive for the for conducive more nment neration neration ig ra o therapeutic for area ging Ndufs4 ies, e impair normal cell cell normal impair e pathways contributes pathways e se per 99,100 e transcriptional transcriptional e ncot mouse knockout n tee is there and PH and PDHc . o be be o Page 20of58 Page 21of58 Ndufs4 ahas hc my n un le mtcodil func mitochondrial alter turn in may which pathways rise ad aa gnla n odtos uh s L as such conditions in ganglia basal and brainstem partial block in NADH oxidation, with a concomitant a with oxidation, NADH in block partial elev that be could explanation alternative possible ri regions brain nldn truh leain o p we lci aci lactic when pH of alterations through including to contribute may and generation, energy for related to nutrient sensing referred to earlier. to referred sensing nutrient to related proteins to damage oxidative increased of evidence hoi srs ta frhr opoie clua fu cellular compromises further that stress chronic nrae i RS rdcin o o awy correlate always not do production ROS in increases degradation are thus promising agents for treating agentsfor thus promising degradationare inhib PARP or synthesis NAD boost can that riboside elcig hgl rdcd tt o te respirator the of state reduced highly a reflecting ratio. elevation of lactate. of elevation defec molecular the of consequence relevant Another maytheref pathogenesis disease oxidative to stress trials. currently are which RP103, and EPI743 antioxidants in diseases, mitochondrial other and LS for therapy emerg therefore has stress oxidative of Alleviation 105 109 ncot mice. knockout This redox imbalance may lead to dysregulation of of dysregulation to lead may imbalance redox This nrae RS r as ipiae i te activatio the in implicated also are ROS Increased 106

Accepted susc Article different to contribute potentially could and

2 Increased lactate levels reflect a greater utiliza greater a reflect levels lactate Increased 101 oee tee eut hv be inconsistent, been have results these However This article isprotected by copyright. All rights reserved. 21 21 94,105 Annals ofNeurology John Wiley& Sons NAD metabolism varies in different different in varies metabolism NAD mitochondrialdiseases. ore be multifaceted. ore be y chain. This typically leads to a a to leads typically This chain. y nction. ated ROS production is simply simply is production ROS ated in affected brain regions of the of regions brain affected in S. Drugs such as nicotinamide nicotinamide as such Drugs S. ed as a promising avenue of of avenue promising a as ed decrease in the NADthe in decrease development in LS patients, patients, LS in development ih neurodegeneration. with oi ensues. dosis cluding the development of of development the cluding being examined in clinical clinical in examined being tion and produce a state of of state a produce and tion ts observed to cause LS is is LS cause to observed ts itors that can block NAD NAD block can that itors 110,111 the signaling pathways pathways signaling the The contribution of of contribution The n of inflammatory inflammatory of n tion of glycolysis glycolysis of tion 16 An observed observed An eptibility of of eptibility 107,108 102,103 + /NADH /NADH

104 and and A A ai o dsae nbe acs t acrt genetic accurate to access enables disease of basis emphasizing intervention, therapeutic from benefit ahas hrpuial. hrceiain f h p the of Characterization therapeutically. pathways disease and levels lactate CSF between correlation group. current is there diseases, mitochondrial other Like Conclusion oeua bss f ies i L ptet. Furtherm patients. LS in disease of basis molecular Acknowledgements Acknowledgements novel therapeutics. of importan is pathology disease underlying mechanisms o Consolidating patients. for outcomes clinical and potentia the has therefore and LS, of basis genetic the transformed has MPS technologies. reproductive ihn h brain. the within reduct a reflect part in to suggested was treatment new therapies. new therapies. grea have therefore could pathology disease driving ellr yfnto i dsae ahgnss ad t and pathogenesis, disease in dysfunction cellular s This assembly. I complex in defect primary the on ac be could lifespan in increase an and improvement h ptooia sgiiac o lcae Interesti in lactate. decline neurological and development of significance pathological the 112

Accepted biochemical and genetic several are there However Article 97 infcnl, hs td as dmntae ta n that demonstrated also study this Significantly,

This article isprotected by copyright. All rights reserved. 22 22 Ndufs4 Ndufs4 Annals ofNeurology John Wiley& Sons knockout mice following rapamycin rapamycin following mice knockout ly no effective treatment for LS as a as LS for treatment effective no ly ion in toxic glycolytic metabolites metabolites glycolytic toxic in ion the importance of determining the determining of importance the l to markedly improve diagnostic diagnostic improve markedly to l hieved independently of an effect an of independently hieved severity in LS patientsLS in severity ur understanding of the cellular cellular the of understanding ur ore, confirmation of the genetic genetic the of confirmation ore, t utility for the development of of development the for utility t he validity of targeting these these targeting of validity he t for enabling the development development the enabling for t recise molecular mechanisms mechanisms molecular recise ngly, attenuation of lesion lesion of attenuation ngly, prah o dtriig the determining for approach upports the role of broader broader of role the upports counseling and assisted assisted and counseling forms of LS that can can that LS of forms eurological eurological 6 supports Page 22of58 Page 23of58 pathological features of Leigh syndrome and on mech on and syndrome Leigh of features pathological Nothing toNothingreport.

AcceptedInterest of Potential Conflicts the m reviewof toand drafting authors contributed Article o publications reviewing to contributed authors All contributions Author Charity. Children’s Hospital OrmondStreet Shamima Program. Support Infrastructure Operational th and Lake Nicole to Award Postgraduate Australian Fellowship Research Principal NHMRC an Foundation, Australia the (NHMRC), Council Research Medical and from grants by supported was research authors' The

This article isprotected by copyright. All rights reserved. 23 23 Annals ofNeurology John Wiley& Sons anuscript. anuscript. anisms of disease causation. All All causation. disease of anisms the Australian National Health Health National Australian the Rahman is supported by Great Great by supported is Rahman n the genetics, clinical and and clinical genetics, the n e Victorian Government's Government's Victorian e n Mitochondrial Disease Disease Mitochondrial n to David Thorburn, an an Thorburn, David to biochemical and DNA abnormalities. Ann Neurol 1996; abnormalities.Neurol Ann andbiochemical DNA Neurosurg 1987;89:217230. Neurosurg1987;89:217230. acid methylmalonic elevated with encephalomyopathy et SorensenN, al. Mito FJ, Hansen Ostergaard E, 4. Genet1993;53:488496. Sague in deficiency oxidase cytochromeC aspectsof etal. Clinic J, Larochelle Mitchell C, G, Morin 3. Leighsyndrom et al. Dahl RahmanHH, Blok RB, S, 2. inchildr disorders chain mitochondrialrespiratory birt ThorburnMinimum DR. Halliday SkladalD, J, 1. References and CoQ10 deficiency due to decaprenyl diphosphate diphosphate to due decaprenyl deficiency andCoQ10 s et al.Leigh Quinzii CM, LC,M, Schuelke Lopez 9. mutations. Am J Hum Genet 2006;79:11251129. Hum 2006;79:11251129. mutations.Am J Genet mitochondrial encephalo(myo)pathy. A review of thereviewof A mitochondrialencephalo(myo)pathy. EM,et al.Eekhoff L CillessenJP, van PM, Erven 8. Clin 2013; Neurosci syndrome.J Leigh childrenwith biochem Liuand Wuet al.Genetic TF, YY, Ma YP, 7. survival and of predictors syndrome:diseasecourse multice et al.A IF,Isohanni P, K, Coo Sofou De 6. 1991;337:13111313. from diagnosis genetic molecular encephalopathies: et al.Mi Brockington M, MG, Sweeney HammansSR, 5. 2007;130:853861. mutations.Brain

Accepted Article

This article isprotected by copyright. All rights reserved. 24 24 Annals ofNeurology John Wiley& Sons en. Brain 2003;126:19051912. 2003;126:19051912. en. Brain . Orphanet J Rare Dis 2014;9:52. 2014;9:52. Dis Rare J Orphanet . blood samples. Lancet Lancet samples. blood nayLacSaintJean. Am J Hum Am J nayLacSaintJean. 20:15911594. 20:15911594. literature. Clin Neurol Neurol literature.Clin synthase subunit 2 ( 2 subunit synthase al, metabolic, and genetic metabolic,and al, is causedby is 39:343351. 39:343351. nter study on Leigh on study nter chondrial eigh syndrome, a syndrome, eigh yndrome withnephropathy h prevalence of of prevalence h ical findings in Chinese Chinese in icalfindings e: clinical features and and clinical features e: tochondrial tochondrial SUCLA2 PDSS2

) Page 24of58 Page 25of58 pathological consequences. Brain 1994;117 ( Pt 6):1 Brain 1994;117 consequences. pathological pathogenesis. J Neuropath 2015;74:48249 Neurol Exp Neuropath pathogenesis.J Neurosurg Psychiatry 1951;14:216221. 1951;14:216221. NeurosurgPsychiatry Neurol 2013;28:15311534. Neurol2013;28:15311534. necrotizing encephalopathy in two sibs. Arch Dis Ch Dis Arch two sibs. in necrotizingencephalopathy et La al. Elwood JS, RW, Brookfield WorsleyHE, 20. 16. Lake NJ, Bird MJ, Isohanni P, et al. LeighIsohanni synd et al. Bird P, MJ, LakeNJ, 16. Leigh's disease. Tissue responses to cellular energ cellular to Leigh'sresponses Tissue disease. factorsPathogenicund Harding CavanaghBN. JB, 15. Clin Neurosci 2012;19:195202. Latead et al. Marotta R, B, Infeld McKelvie P, 14. two fa of study a reviewand A encephalomyelopathy. et al. CarpenterS, Andermann F, MontpetitVJ, 13. Ped dysfunction. hepatic with apresenting newcase 3methylg Lahat IV Type O, E. Broide Elpeleg E, 12. 19. Leigh D. Subacute necrotizing encephalomyelopat necrotizing LeighD. Subacute 19. Psy Neurosurg Leigh Neurol J treatmentof syndrome. et al. J, Schaper RJ, A Rodenburg BaertlingF, 18. 2000;21:15021509. Neuroradiol AmAJNR J ima MR Y. Leigh serial Tanabe syndrome: AriiJ, 17.

Accepted Articlethe m.13513G>A Cl Mutation:Expanding Mitochondrial Bornstein L et al. B, MD, L, MonlleoNeilaToro 11. Pathol19 A Anat Histopathol Arch disease.Virchows et al.Cardiomyop R, Seitz Langes H, K, Frenzel 10.

This article isprotected by copyright. All rights reserved. 25 25 Annals ofNeurology John Wiley& Sons y deprivation and their clinicotheirand ydeprivation iatr Neurol 1997;17:353355. Neurol 1997;17:353355. iatr 3571376. 3571376. ild 1965;40:492501. ild1965;40:492501. milies. Brain 1971;94:130. milies.1971;94:130. Brain 85;407:97105. 85;407:97105. chiatry 2014;85:257265. 2014;85:257265. chiatry guide to diagnosis and to guidediagnosis ult onset Leigh syndrome. J J onset Leigh syndrome. ult 2. 2. rome: neuropathology and and neuropathology rome: Subacute necrotizing necrotizing Subacute athy associated with Leigh's Leigh's with athyassociated eigh Syndrome andthe eighSyndrome ging and clinical followup. followup. clinical gingand inical Spectrum. J Child J Spectrum. inical lutaconic (3MGC) aciduria: (3MGC) lutaconic ctic acidosis withacidosis ctic hy in an infant. J Neurol in infant. hy an J erlying the lesions in lesions theerlying NDUFS2 pyruvate, malate and 2oxoglutarate in muscle and l muscleinand malateand2oxoglutarate pyruvate, patient with subacute necrotizing encephalomyelopat necrotizing patientsubacute with in Leighlike syndrome due to due Leighlike insyndrome V, et al. CormierDaire ThisBernd LaugelV, V, 27. 2013. 2013. Chinesea boy with geneof succinatedehydrogenase frame Liu Wuetcompound al.Two TF, YY, Ma YP, 28. encephalomyelopathy (Leigh syndrome) associated wit associated syndrome) (Leigh encephalomyelopathy etal.Ruitenbeek W, FJ, Gabreels VanErven PM, 23. 1977;60:850857. m in deficiency oxidasecytochrome c awith patient et LA,Trijbels al.Lei Monnens JM, WillemsJL, 22. of mitochondrial respiratory chain complex Iallows mitochondrial complex chain respiratory of et constant M, al.A Rio AssoulineM, Jambou Z, 25. Genet 2012;49:578590 Med molecularJ andgenetics. clin deficiency: ComplexI Rahman S. E, Fassone 24. 1985;72:3642. mitochondrial complex I deficiency due to novel mut to novel deficiency Idue mitochondrialcomplex et al.Leigh RobinsonB, R, SE, Marin Mesterman 26. 1069. Biochim Leigh with syndrome. mutations in patients et L,de A, al.Pyruvate Miller Farmer Veath T, 21.

Accepted . Gene2013;516:162167. Article

This article isprotected by copyright. All rights reserved. NDUFV1 mutations. Pediatr Neurol 2007;36:5457. mutations.2007;36:5457. Pediatr Neurol 26 26 Annals ofNeurology John Wiley& Sons iver. Acta Neurol Scand Scand iver.Neurol Acta rapid identification of of identification rapid uscle tissue. Pediatrics Pediatrics tissue. uscle hy. 1973;23:429. 1973;23:429. Neurology hy. ations in ations Biophys Acta 2012;1822:1062 Acta Biophys encephalopathy. Brain Dev. Brain encephalopathy. carboxylase deficiency in a in deficiency carboxylase . . h disturbed oxidation of of hoxidation disturbed Earlyonset ophthalmoplegia Earlyonset ophthalmoplegia gh's encephalomyelopathy in in encephalomyelopathy gh's and similar assembly defect assemblydefect and similar ical features, biochemistry biochemistry icalfeatures, Subacute necrotizing necrotizing Subacute syndrome associated with with syndrome associated shift mutations inmutations shift NDUFV1 and NDUFS4

Page 26of58 Page 27of58 phenotypically distinct form of Leigh syndrome with of form phenotypicallydistinct 35. Wedatilake Y, Brown R, McFarland R, et al.McFarland R, R, WedatilakeBrown Y, 35. Metab2003;79:288293. OXPHO to due CoQresponsive possibly Leigh syndrome et Nissenkorn A, A, Levine LeshinskySilver E, 34. 2012;22:7686. deficie coenzymeQ(1)(0) of treatment diagnosisand Inter 176thENMC M. Hirano RahmanClarke CF, S, 33. 2 Neurol two Ann sisters. in Leigh'sencephalopathy S, et al. DiMauro L,F, Trijbels VanMaldergem 32. phenotype. biochemical and molecular,the clinical 36. Liolitsa D, Rahman S, Benton S, et al. Is the m the al.Is Rahman BentonS, et LiolitsaD, S, 36. Rare 2 Dis study. J centreOrphanet history natural 37. Debray FG, Morin C, Janvier A, et et al. C, DebrayMorin JanvierA, FG, 37. mutations?Ne causing Ann MELAS genefor a hotspot et al.Mu RG, Feichtinger KochFreisingerP, J, 31. 2006;89:214221. mutation a by nuclear caused mitochondrialdisease et al. AJ, Duncan HargreavesIP, AT, Pagnamenta 30. 1995;11:144149. mitochondrialrespira inresults gene dehydrogenase et al.Mutat Chretien D, P, Rustin BourgeronT, 29.

Accepted Genet 2011;48:183189. Med deficiency.J Article

This article isprotected by copyright. All rights reserved. 27 27 Annals ofNeurology John Wiley& Sons RP CLRPPR 013;8:96. 013;8:96. Orphanet J Rare Dis 2015;10:40. Rare 2015;10:40. Dis OrphanetJ tory chain deficiency. NatGenet chain tory deficiency. in complex II. Mol Genet Metab Mol Genet Metab inII. complex 002;52:750754. 002;52:750754. SURF1 Disord Neuromuscul ncy. oxidase oxidase c cytochrome itochondrial complex I complex itochondrial tations in in tations ion of a nuclear succinate of ion mutations cause a mutationscause al. Neonatal liver failure and and liverNeonatal failure al. Coenzyme Qresponsive Qresponsive Coenzyme urol 2003;53:128132. urol2003;53:128132. Phenotypic variability of variabilityof Phenotypic S deficiency. Mol Genet deficiency. MolGenet S deficiency: a multi a deficiency: national Workshop: national TTC19 : expanding :expanding ND5

ETHE1 phenotype correlation. 2013;13:81081 Mitochondrion correlation. phenotype petechiae, and ethylmalonic aciduria. Pediatr Neuro aciduria.Pediatr andpetechiae, ethylmalonic Burlinaet al.Identif AB, MineriM, Rimoldi R, 38. 41. Mourier A, Ruzzenente B, Brandt T, et al. Loss Brandtal.Loss B, et T, Ruzzenente Mourier A, 41. 2003;100:605610. geno integrative by deficiency cytochromec oxidase etal.Identific Miller Lepage K, P, VK, Mootha 40. natural history of naturalof history Szymanska D, PronickaPiekutowskaAbramczuk E, 39. J GenetMed 2008;45:473478. 45. Pitceathly RD, Rahman S, et al. S, WedatilakeY, Rahman PitceathlyRD, 45. 2010;16:869871. Med isin effective metronidazoleNacetylcysteine and al.I, Dweikat et Combin AB, ViscomiBurlina C, 44. 2009;15:200205. ethyl in sulfide toxicity fatal dioxygenase, causes 42. GarciaSilva MT, Ribes A, Campos Y, al.Synd Campos Y, et A, Ribes GarciaSilva MT, 42. Genet 2014;23:2580259 Mol Hum synthase deficiency. 43. Tiranti V, Viscomi C, Hildebrandt T, et al.Los T, et Hildebrandt TirantiC, Viscomi V, 43. mitochondrial DNA depletion. Am J 2005;76 Genet depletion.Hum Am J mitochondrialDNA e associatedwith activity is synthase succinylCoA al.et Defi HershkovitzE, C, Miller Elpeleg O, 46. 2013;3:17951805. Disease. CellRep Linke Oxidasec Cytochrome a Subunit Dysfunctionof

Accepted Articlewithet 14 patientsof presenting gene cohorta in SCO2 deficiency in 36 Polish children confirmed the gen theconfirmed children in Polish deficiency36 This article isprotected by copyright. All rights reserved. 28 28 Annals ofNeurology John Wiley& Sons malonic encephalopathy. Nat Med Nat Med encephalopathy. malonic ethylmalonic encephalopathy. Nat Nat encephalopathy. ethylmalonic ncephalomyopathy and and ncephalomyopathy l 1997;17:165170. l1997;17:165170. mics. Proc Natl Acad Sci U S A A S mics. SciU Acad Natl Proc ciency of the ADPforming the ciencyADPforming of s of of s 6. 6. NDUFA4 ication of new mutationsnewthe in icationof d to Human Neurological toNeurological Human d ation of a genea human causing of ation of of 2. 2. hylmalonic encephalopathy. encephalopathy. hylmalonic ed treatment with oral oral treatment with ed rome of encephalopathy, romeof :10811086. :10811086. LRPPRC ETHE1 Debinska T, et al. The al.The et T, Debinska Mutations Underlie , a mitochondriala , causes ATP ATP causes otype Page 28of58 Page 29of58 patients and five novel patients and five LJH, et al., editors. GeneReviews(R). Seattle (WA)1 Seattle etGeneReviews(R). LJH, editors. al., Walla HH, Ardinger In:MP, Adam Pagon andRA, NARP. DNAAssoci Mitochondrial Rahman S. ThorburnDR, 55. 161. and/orWolffParkinsonWhit activity,atrophy optic combine Leigh insyndrome mostfrequent mutation is van et denal.Th C, Elzen Siers RuiterMH, EM, 54. Ann Leigh'smutationdisease. cause can G13513A DNA l mutantLowet al. Chow CW, A, Boneh KirbyDM, 53. mitochondrialDNA novel et al.Leig M, Hutchinson Morris AA, Taylor RW, 52. Genet Metab 2014;111: Mol genecandidatescreening. et al.Ne V, Serre Haudry C, ValayannopoulosV, 49. Meta MolGenet patients. the characterise tobetter of usethe and descriptions depletionnew syndrome: et F, J, GarciaVilloria Tort NavarroSastreA, 48. Res Pediatr mitochondrialhepatoencephalomyopathy. et al.Succin JA, Thomas VanHove Saenz MS, JL, 47. 51. Haack TB, Gorza M, Danhauser K, etal.Phenotyp K,Danhauser HaackM, Gorza TB, 51. Metab2011;14:428434. mito impaired causing formylation of humandisorder Accepted Articleal. et Mutati Kohrer C, HershmanSG, TuckerEJ, 50. 2010;10:335341. Mitochondrion this caus rare of spectrum the expanding phenotypic

MTFMT ND5 This article isprotected by copyright. All rights reserved. mutation. Eur J mutation.Hum2002;10:141144. Genet Eur J mutations identified by exome sequencing and sequencing mutations by exome identified 29 29 Annals ofNeurology John Wiley& Sons b 2012;107:409415. 2012;107:409415. b e of mild methylmalonic aciduria.methylmalonicmild of e e. Eur J Hum 2007;15:155 Genet Eur e. J as a helpful tool ascitrate helpful a synthase 993. chondrial translation. translation. Cell chondrial al. Mitochondrial DNA DNA al.Mitochondrial d with reduced complex I I complex reduced d with 2010;68:159164. 2010;68:159164. 342352. 342352. e mitochondrial 13513G > A A > mitochondrial13513G e Neurol 2003;54:473478. 2003;54:473478. Neurol ons in ons w h disease associated with a with associated disease h ic spectrum of eleven icof spectrum ylCoA deficiency: a ylCoAligase deficiency: ce SE, Amemiya A, Bean Bean ceAmemiya A, SE, SUCLG1 oad of mitochondrial oadof ated Leigh Syndrome LeighSyndrome ated MTFMT patients underlie a patients. Mol Genet Metab 2012;106:385394. 2012;106:385394. Metab patients.MolGenet correlation with genotype. Mol Genet Metab 2012;107 MolGenet genotype. Metab correlation with complex dehydrogenase pyruvate in survivaloutcomes et al.Spectru K,Zhang S, OkajimaSD, DeBrosse 63.

Acceptedclinical,biochem deficiency: complex dehydrogenase et al.The SH, Subramony PatelTW, O'Brien KP, 62. 1999;22:899914. tissue agerelat of lack or show8993 a nucleotide et al.Mitochon McGillJJ, White S, SL, Shanske 61. G Hum theinoffspring. Leigh resulting in syndrome gene (T8993G) subunit synthase 6 mitochondrialATP et Larsson al.De NG, M, Houshmand TuliniusMH, 60. (3):61Brain 1993;116Pt mitochondrial mutantDNA. cli Relationshipof (MERRF). fibres with raggedred Articlesyndr the mutation and RNA(Lys)A>G(8344) transfer et al.T Brockington M, MG, Sweeney HammansSR, 59. phenotypes.mutationActa different in A3243G four et al.Singlefiber R, Iwanaga Koga KogaA, Y, 58. 412. Leigh's in syndr mitochondrialgene 6 theinATPase et al Gabreels FJ, BG, van deEngelen DD, Vries 57. Hum 1992;50:852858. is Genet high. Am J mtDNA w Leighdisease cause can at 8993 mutation (TG) al.Feigenbaum et J, A, Christodoulou TatuchY, 56.

This article isprotected by copyright. All rights reserved. 30 30 Annals ofNeurology John Wiley& Sons ed variation. J Inherit Dis Metab J variation. ed nical phenotype to proportion of toof proportion phenotype nical ome. Ann Neurol 1993;34:410 ome. Neurol Ann hen the percentage of abnormal theof henpercentage enet 1995;96:290294. enet1995;96:290294. Neuropathol 2000;99:186190. 2000;99:186190. Neuropathol ical and genetic features in 371 features genetic and ical 7632. 7632. :394402. :394402. (PDC) deficiency: lack of of lack deficiency: (PDC) with rapid segregation withrapidsegregation analysis of mitochondrial of analysis ome of myoclonic epilepsy of ome Heteroplasmic mtDNA Heteroplasmic drial DNA mutations at DNA drial . A second missense mutationmissense second A . mneurological and of spectrum of pyruvate of spectrum novo mutation in the in mutation novo he mitochondrial DNA mitochondrialDNA he Page 30of58 Page 31of58 pathway. Am J Hum Genet 2011;89:806812. HumJ pathway.Genet 2011;89:806812. Am novel et Leigh al. Martin Leber DM, QuinonezSM, SC, 66. Rare20 Dis J Orphanet ketoglutaratedehydrogenase. gene et al.Mutation Habarou F, A, SorezeBoutron Y, 65. 20 Mitochondrion achallenge. mutations:diagnostic Teszas et A, al.Fem RJ, Rodenburg WillemsenM, 64. disease maps to 2q36.3 and is due to mutationsto in ismaps toand due disease2q36.3 et al. Jr., B Acierno AlYamani JS, E, Zeng WQ, 70. encephalopathy presenting in adolescence. BMJ Case BMJ in adolescence. presenting encephalopathy etal.Trea DeVileCJ, WedatilakeY, E, Fassone 72. Orpha monitoring. treatment and deficiency:outcome etal Serrano M, Molero M, OrtigozaEscobar JD, 71. 2005;77:1626. Moroccan founder mutation in Moroccanfounder et al.Exome OevelenJ, van Kamps R, GerardsM, 68. Brain2014;137:366379. deficiency in encephalopathic children with defects with children encephalopathic indeficiency K,et al. Thi Freisinger P, Schlachter Mayr JA, 69. 2013;136:882890. Brain Leighsyndrome. hyperglycinemia is caused by mutations in by is caused hyperglycinemia et al Swanson MA, Friederich MW, Baker2nd, PR, 67. LIPT1 DLD

mutation causing E3 deficiency. Pediatr Neurol 201 Neurol Pediatr mutationdeficiency. E3 causing

Accepted Articledeficiency secondary fo diseasewith Leigh a cause

This article isprotected by copyright. All rights reserved. SLC19A3 as a new cause of earlychildhood fatal earlychildhood cause of as new a 31 31 LIAS Annals ofNeurology John Wiley& Sons , , BOLA3 SLC19A3 in the pyruvate oxidation oxidation pyruvatethe in 06;6:155159. 06;6:155159. 13;8:192. 13;8:192. net J Rare Dis 2014;9:92. Rare 2014;9:92. Dis net J amine pyrophosphokinase pyrophosphokinase amine Rep 2013;2013:200838. 2013;2013:200838. Rep table Leighlike tableLeighlike s in human lipoyltransferase lipoyltransferase in human s iotinresponsive basal ganglia basal iotinresponsive and the novel gene the gene and novel . Thiamine transporter2 transporter2 Thiamine . sequencing reveals a novela reveals sequencing syndrome in a girl with a girlaa with syndrome in ales with with ales . Variant non ketotic non Variant . . Am J Hum Am . Genet J ralpha and pyruvate 3;48:6772. 3;48:6772. PDHA1 gene GLRX5 . . phosphorylation. Mol Genet Metab 2006;88:4752. 2006;88:4752. Genet Metab phosphorylation.Mol polymerase gamma in patients with mitochondrial mitochondrial DNA with ingammapolymerasepatients like syndrome (MEGDEL association) in four patients infour (MEGDELassociation) like syndrome deafn with aciduria sensorineural methylglutaconic et M, Huizing RJ, al.Ass S, Wortmann Rodenburg 79. Nat Ge dystonia deafness. cause and trafficking and remodelinggene etal.Muta GardeitchikT, FM, Vaz SB, Wortmann 78. 2009;30:248254. 77. Taanman JW, Rahman S, Pagnamenta AT, et al.Ana Rahman AT, Pagnamenta S, TaanmanJW, 77. Paediatr J Eur Leigh's encephalopathy. findings of Alpers an tospectrumsyndrom myocerebrohepatopathy ( et al.Poly Schlesser P, B, ScalaisFrancois E, 76. 1992;8 Neuropathol microscopicActa study. electron mitochondriopathyof a associateddistributionwith etal.Brain KobayashiS, YamadoriKurose A, I, 75. 1996;47:13201323. deletion.Neurology produ ATP impaired with Pearsonsyndrome associated et LeighPons R, al. Barmada MA, Santorelli FM, 74. 2010;30:606614. Neuropathology onecase. autopsy mutation,and m.13513G>An with syndromeassociated et al.S, pattern Phenotypic Yao Wang Z, XK, Qi 73. POLG

Accepted evol stage withatwo a child in ): course clinical Article SERAC1 impair mitochondrial function and intracellular ch intracellular mitochondrial function and impair This article isprotected by copyright. All rights reserved. 32 32 Annals ofNeurology John Wiley& Sons Neurol 2012;16:542548. 2012;16:542548. Neurol Pearson's syndrome: light and and light Pearson's syndrome: net 2012;44:797802. net 2012;44:797802. ess, encephalopathy, and Leigh and encephalopathy, ess, merase gamma deficiency deficiency gamma merase 4:337341. 4:337341. with a disorder of the oxidative of disorder a with ction and a novel mtDNA mtDNA and ctionnovel a ution from infantile from ution lesions of the Leightypethe of lesions e and neuropathological neuropathological and e depletion. Mutat Hum europathological findings in findings europathological s of MELAS/LS overlap overlap MELAS/LS of s type neuropathology in type neuropathology ociation of 3 of ociation tions in the phospholipid intionsphospholipid the lysis of mutant DNA mutant DNA lysisof olesterol olesterol Page 32of58 Page 33of58 Neuropediatrics 1986;17:129131. Neuropediatrics1986;17:129131. 2006;163:94112. 2006;163:94112. energ mitochondrial on vitaminfamily rolethe B of et al.N, Mitocho Bruce WR, Shangari Depeint F, 87. mitochondrialung in fi human impairssynthesis and et al.Biotin Erlitzki R, Newberry AtamnaJ, H, 86. 2013;110:248254. Genet Metab disorder.Mol t clues for deprivation:nutritional that biotin of met alteredcarbon and deficit showcellular energy Pindolia K,et al. B, Wolf HernandezVazquezA, 85. acidemia in biotinidase deficiency. A treatable con treatable A deficiency. acidemiabiotinidase in et al.Neurolog Munnich A, OgierH, Mitchell G, 84. 1989;26:260266. Res withPediatr lethal outcome. (Leigh subacute encephalomyelopathy of necrotizing al.Bio Wick et H, TM, BaumgartnerSuormala ER, 83. Hum2010;86:639649. Genet mutationapo in a with associated encephalomyopathy al.et S Invernizzi F, I, GhezziSevrioukova D, 82. metabol valine metabolism affecting inborn errorof

Accepted Articleet al. R, Wanders PetersBuck N, H, 81. 2007;80:195199. AmGenet Hum J in progress results hydroxyisobutyrylCoA et al.Muta Ruiter ClaytonJP, LoupattyFJ, PT, 80.

This article isprotected by copyright. All rights reserved. 33 33 ECHS1 Annals ofNeurology John Wiley& Sons he pathogenesis in the human inherited humanthe inherited in pathogenesis he dition mimicking Leigh'sdisease. mimicking dition abolism similar to to similar expression gene abolism mutations in Leigh disease: a newa mutations Leigh disease: in y metabolism. Chem metabolism.Chem Interact Biol y ism. Brain 2014. ism.Brain 2014. broblasts. J 2007;137:2530. Nutr broblasts.J ive infantile neurodegeneration. neurodegeneration. infantile ive syndrome). Report of a casea of Report syndrome). evere Xlinked mitochondrial Xlinked evere ptosisinducing factor. Am J Am J factor. ptosisinducing deficiency inhibits heme inhibits deficiency tions in the gene encoding 3 gene thein encoding tions ical deterioration and lactic and deterioration ical ndrial function and toxicity: toxicity: and ndrial function Biotinidase knockout miceknockout Biotinidase tinidase deficiency: a cause cause a tinidasedeficiency: 2015;38:437443. 2015;38:437443. practi clinical in mitochondrial patients suspected et al. Smeitink Who JA, DA, Koolen SB, Wortmann 96. Pharmacol 2014;171:18 Br J mitochondrialdisorders. Nextge Brilhante A. Suomalainen V, Carroll CJ, 95. 2013;8:e69282. One signalingnetwork. PloS globalthe of dysregulation tissuespecific causes etre al. M, Peng Primary Tsukikawa Zhang Z, M, 94. 2008;134 Cell biology. Idisease elucidates complex mito et al.A B, Chang CalvoSE, PagliariniDJ, 93. diseases.2007;27:2330. Biosci Rep et al.Neuropa Tonin P, Tomelleri Filosto G, M, 92. Neurol 1 Ann humandevelopment. of functional brain Positron e JC. Mazziotta ME, Phelps Chugani HT, 91. 2014;111:1301013015. human of developmen brain implications evolutionary LI,al.Meta Grossman et HT, Chugani KuzawaCW, 90. 15. A Mol Physiol Comp Biochem hominidevolution. brain etal. Snodgrass JJ, Robertson ML, LeonardWR, 89. Orphanet dehydrogenase. andchainpyruvate enzymes mult of deficiency combined diseasewith Leighlike

Accepted Article etal. Heales SJ, HR, Waterham FerdinandusseS, 88.

This article isprotected by copyright. All rights reserved. 34 34 Annals ofNeurology John Wiley& Sons transcriptome and nutrientsensing transcriptomeand nutrientsensing ce. J Inherit Dis Metab J ce. :112123. :112123. iple mitochondrial respiratory mitochondrial respiratory iple 371853. 371853. t. Proc Natl Acad Sci U S S A U AcadSci Natl Proct. 987;22:487497. 987;22:487497. J Rare Dis 2013;8:188. 2013;8:188. Dis Rare J chondrial protein compendium compendium chondrialprotein thology of mitochondrial thologyof Integre Physiol 2003;136:5 Integre Physiol neration sequencing for for sequencing neration

Metabolic correlates of correlatesof Metabolic HIBCH spiratory chain disease spiratorydisease chain mission tomography study study tomography mission le exome sequencing of of leexomesequencing bolic costs and costs bolic mutations cause can Page 34of58 Page 35of58 potentiates dopamine death induced by microt induced bydeath neuron potentiatesdopamine phenotype of two mitochondrial disease mouse modelsmouse two mitochondrialdisease of phenotype Ndufs4 complex deficient fibroblast complexdeficient pyruvate dehydrogenase dysfunction diverges from embryonic fibroblasts in fibroblasts embryonic fromdysfunction diverges etal.Neur Wijeyeratne JC, Komen XW, BirdMJ, 103. 2011;192:873 Cellmodel.J Biol Parkinson'sdisease 102. Choi WS, Palmiter RD, Xia Z. Loss of mitochond Lossof Xia Z. ChoiRD, WS,Palmiter 102. 2010;107:109961 A S Sci U Acad syndrome.Natl Proc 99. Glushakova LG, Judge S, Cruz A, et Increase Cruz A, al. S, LG, Judge Glushakova 99. 101. Quintana A, Kruse SE, Kapur RP, et al.Complex KruseRP, SE, Kapur A, Quintana 101. 2009;132:833842. to dysfunction fromcomplex deficiency: I LP, van den Heuvel WJ, Koopman DistelmaierF, 100. 2011;104:255260. Surf1 metaboli enhanced brain with functionisassociated et al.Deepa SS, Decreased Lin DA, AL,Pulliam 104. Rep 2014. al. Cerutti et R, T, CivilettoVaranita G, 98. 1528. synmodelLeigh mousea inof mitochondrialdisease in mTOR al. et ME, Kayser EB, Yanos SC, Johnson 97. deficient mice. J Cereb Blood Flow Metab 2013;33:1 Metab Cereb Flow mice.Blood J deficient

Acceptedencephalopathy in progressive results brain the in Article

This article isprotected by copyright. All rights reserved. 35 35 Annals ofNeurology John Wiley& Sons Opa1 sm, blood flow, and memory in and flow, sm,blood the clinical disease. Brain Brain disease. clinical 882. 882. s. Mol Genet Metab Metab MolGenet s. drome. Science 2013;342:1524 Science drome. overexpression ameliorates the ameliorates overexpression ubule dysfunction in a a in ubuledysfunction . Cell Metab 2015;21:845854. Metab 2015;21:845854. Cell . Ndufs4fky/fky d superoxide accumulation in superoxideaccumulation d 1001. 1001. in vitro mitochondrial vitro in I deficiency due to loss of to of loss deficiency I due resembling Leigh Leigh resembling rial complex rialcomplex activity I onal and and onalastrocyte et al. Mitochondrial etal.Mitochondrial 6051611. 6051611. hibition alleviates alleviates hibition mouse. Biosci et Founder al.A DA, Smith Lim Stroud KR, SC, 114. Anaesth Paediatr 2013;23:785 mitochondrialdefects. consideratio Anesthetic PG. NiezgodaMorgan J, 113. Rev Syst 2012;4:CD0044 Database Cochrane disorders. etal. Trea Turnbull DM, G, Majamaa Pfeffer K, 112. met of fromerrors inborn lessons stress responses; signRedox GregersenN. Cornelius OlsenN, RK, 111. 2013;13:106118. resp and inflammatory the Mitochondrialdysfunction Vaamonde RiveiroNaveira RR, LopezArmadaMJ, 110. Metab2015. Dis mittreatment in of aspects RahmanEmerging S. 109. EM vitaminB3. a riboside, myopathynicotinamide by Paetauet al.Effective I, M, KhanAuranen NA, 108. 2014;19:10421049. mitochon model mousea in of correctsphenotype the et al.NAD(+ C, Lamperti Cerutti PirinenE, R, 107. Biogerontology2014;15:177198. influe for targets rats: ageing of potential Wistar NA et al.Mapping GrantR, BraidyPoljak A, N, 106. 2014;6:705707. m mitochondrial a treatingto key increasing NAD(+) Sa ZM. ChrzanowskaLightowlers LightowlersRN, 105.

Hum Genet 2014;94:209222. Hum2014;94:209222. Genet Lebanesein Individu Deficiency IV IsolatedComplex Accepted Article

This article isprotected by copyright. All rights reserved. 36 36 Annals ofNeurology John Wiley& Sons ncing brain senescence. senescence. brain ncing abolism. J Inherit Metab Dis 2015. 2015. Dis Inherit abolism.Metab J 793. 793. yopathy? EMBO Mol Med MolMed yopathy?EMBO onse. Mitochondrion Mitochondrion onse. drial disease. Cell Metab Cell disease. drial als with Leigh Syndrome. Am J J Am Leigh with Syndrome. als )dependent activation of Sirt1 )dependentactivation of BO Mol Med 2014;6:721731. 2014;6:721731. MolMed BO treatment of mitochondrial of treatment tment for mitochondrial tmentfor D(+) metabolism in the brain metabolismbrain the in D(+) ochondrial disorders. J Inherit J disorders. ochondrial 26. ns in patients with in ns patients Mutation in Mutation alling and mitochondrial allingand lvaging hope: Is lvaging hope: Garcia C, et al. C, Garcia PET100 Causes Causes Page 36of58 Page 37of58 2014. Genet Metab children.Mol the et al.Foun MB, Ivanova Azmanov IvanovDN, IS, 116. Brain 2007;130:862874. dystonia deafness. and Leigh methylmalonicmildaciduria, associated with et a Steuerwald U, C, CarrozzoDionisiVici R, 115. PDHX

Accepted Articlel of caseswith congenital over half gene explains

This article isprotected by copyright. All rights reserved. 37 37 Annals ofNeurology John Wiley& Sons like encephalomyopathy, likeencephalomyopathy, l. SUCLA2 der p.Arg 446* mutation in mutation 446* der p.Arg actic acidosis in Roma in acidosis actic mutations are basis of Leigh syndrome. The graph represents the n the represents graph The syndrome. Leigh of basis ahas f nry eeain Bify prvt is pyruvate Briefly, generation. energy of pathways phosphorylation (OXPHOS). OXPHOS is performed withi performed is OXPHOS (OXPHOS). phosphorylation electron produce to (TCA) cycle acid citric bythe N (le. brvain: I CI CI, I ad C and CIV res V, and IV III, II, I, CIII, Complexes Phosphorylation CII, CI, Abbreviations: (blue). DNA autos (green), Xchromosome the on either gene, the T timeline. the to relative year each in identified eitn sgiiat dacs n h understanding the in advances significant depicting Cyt co and I complex between transfer electron mediates L of understanding our of development The 1: Figure utilizes the energy produced by this electron trans electron this by produced energy the utilizes lcrn poie b te C cce hog te mul the through cycle TCA the by provided electrons tr electron or chain respiratory the as to referred dehydrogenase (PDHc) to produce acetyl coenzyme A ( A coenzyme acetyl produce to (PDHc) dehydrogenase impairme genetic a by caused is (LS) syndrome Leigh Leigh syndrome. of basis Thebiochemical Figure 2: Sequenc Parallel DehydrogenaseComplex. Massively MPS, syndrome; Leigh LS, ares onye (CoQ Q coenzyme carriers as known complexes, multiprotein five by membrane complexes I, III and IV into the intermembrane spac intermembrane the into IV and III I, complexes c

rnfr eetos rm ope II o ope IV complex to III complex from electrons transfers Accepted Article

10 This article isprotected by copyright. All rights reserved. ) and cytochrome cytochrome and ) 38 38 Annals ofNeurology John Wiley& Sons he coloring represents the location of of location the represents coloring he c donors for the pathway of oxidative of pathway the donorsfor (Cyt (Cyt fer to pump protons (Hprotons pump to fer pectively; CoQ pectively; ansfer chain, direct the flow of of flow the direct chain, ansfer of the biochemical and genetic genetic and biochemical the of umber of new LS disease genes disease LS new of umber e, generating a proton gradient gradient proton a generating e, mplex II to complex III, while while III, complex to II mplex complexes I to V, and electron electron and V, to I complexes

acetyl CoA), which is utilized utilized is which CoA), acetyl m (e) o mitochondrial or (red), ome ipoen opee. CoQ complexes. tiprotein metabolized by pyruvate pyruvate by metabolized c ). Complexes IIV, often often IIV, Complexes ). ih syndrome. eigh n the mitochondrial inner inner mitochondrial the n t f h mitochondrial the of nt . The respiratory chain chain respiratory The . V refer to Oxidative Oxidative to refer V ing; PDHc, Pyruvate Pyruvate PDHc, ing; 10 , Coenzyme Q Coenzyme , + ) through ) Timeline Timeline 10 10 ;

Page 38of58 Page 39of58 the 1 the ma and minimum depicting bars error as: represented forms biochemical and genetic the between observed diff Genotypephenotype literature. the in reported of patients for which information was available: available: was information which for patients of CoQ and IV, complexes PDHc, Deficiencyof t V) (complex synthase ATP by harnessed be can that 21, (complex IV deficiency)IV (complex with mutations in in mutations with onse of ages the of representation plot whisker and iue 3: Figure PET100 st and 3 and

eoyepeoye orltos ih epc t dis to respect with correlations Genotypephenotype 10, rd quartiles, with the line within the box representi box the within line the with quartiles,

AcceptedSUCLA2 Article

NDUFS4, NDUFV1 NDUFV1 NDUFS4, , SUCLA2 , 31, and and 31, This article isprotected by copyright. All rights reserved. and and MTFMT MTFMT 39 39 cmlx deficiency) I (complex 12. Annals ofNeurology John Wiley& Sons 10 , can cause LS. canLS. , cause NDUFS4 (combined OXPHOS deficiency) as as deficiency) OXPHOS (combined t, death or last report for patients patients for report last or death t, erences in disease course can be be can course disease in erences ximum, the box edges depicting depicting edges box the ximum, o drive the synthesis of ATP. of synthesis the drive o of disease. Data points are are points Data disease. of 21, 21, ng the median. Number Number median. the ng NDUFV1 , SURF1, PET100 PET100 SURF1, , ae courseease 12, 12, SURF1 . Box Box .

autosomal recessive inheritance. Supplementary Tabl Supplementary inheritance. recessive autosomal by inheritance deletion mtDNA = mtDNA Table Biotinidase Biotinidase PDHc ± OXPHOS mi of impairment secondary cause that genes Disease V Complex IV Complex III Complex QCoenzyme II Complex I Complex dehydrogenase Pyruvate deficiency Biochemical product. each gene of role the on information Mitochondrial DNA DNA Mitochondrial Mitochondrial Mitochondrial translation translation maintenance affected Pathway defects OXPHOS Combined 1 : Genes in which mutations cause Leigh syndrome or syndrome Leigh cause mutations in which Genes :

10 10

Accepted Article * , ^ indicates sporadic inheritance; all other genes genes are other all inheritance; sporadic indicates MTATP6 LRPPRC MTCO3 PDSS2 NDUFA12 NDUFS7 NDUFS1 NDUFV2, NDUF1V, MTND1 PDHA1 UQCRQ, BCS1L, TTC19 BCS1L, UQCRQ, SDHA SLC19A3 FBXL4 BTD BTD AIFM1 SERAC1, ECHS1, HIBCH, MTFMT, GFM1 mtDNA . This article isprotected by copyright. All rights reserved. , , Xlinked inheritance indicated by by indicated inheritance Xlinked

SDHAF1 # * * , PDHB, , , , , , , * , , , ,

NDUFA4 MTND GFM2 TACO1, ETHE1 TACO1, NDUFS8 SLC25A19 , POLG

NDUFAF2 ^ GTPBP3 , MTTI ,

, , 2 , PDHX TSFM, C12orf65, TSFM, * SUCLA2 , , * , , 40 40 MTND3 , , SURF1 NDUFA1 , ,

MTTK TRMU, EARS2 TRMU, , Annals ofNeurology NDUFAF5 ,

John Wiley& Sons

DLAT

, * , , * SUCLG1 , , , COX10

Genes Genes MTTL1 # MTND4 , , , tochondrial energy generation energy tochondrial NDUFS2 e 1 contains additional additional contains e 1 , NDUFA2 DLD , ,

PNPT1 NDUFAF6 , , # , , *

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, maternal maternal , , , * , , associated with with associated IARS2, NARS2IARS2, SCO2 , LIAS

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, ,

, , , , , ,

, Page 40of58 Page 41of58

Complex I I Complex dehydrogenase Pyruvate deficiency Biochemical gene. each entry for be can references Appropriate recessive. autosomal (TPP) pyrophosphate thiamine of in observed absence system. enzyme cleavage glycine the of deficiency (BC dehydrogenase alphaketoacid chain and branched # denot are genes DNAencoded Mitochondrial syndrome. thatcompa is presentation reported a patients with Leigh or Leigh with diagnosed patients in described g in these mutations Pathogenic enzymes. and OXPHOS deh pyruvate the of or activity stability assembly, directl that genes disease syndrome Leigh 1A: Table with additional deficiency of alphaketoglutarate d alphaketoglutarate of deficiency with additional MTND4 MTND4 MTND3 MTND MTND1 LIAS* LIPT1 DLD DLAT PDHX PDHB PDHA1 TPK1 Gene AcceptedSLC25A19 SLC19A3 Article

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†

†

This article isprotected by copyright. All rights reserved. Subunit Subunit Subunit Subunit Subunit transporterCo-factor transporter Co-factor synthesis Co-factor synthesis Co-factor attachment Co-factor Subunit Subunit protein binding Subunit Subunit Subunit function Protein 41 41 ydrogenase complex (PDHc) (PDHc) complex ydrogenase † PDHc deficiency only only deficiency PDHc Annals ofNeurology tible with Leigh or Leighlike Leighlike or Leigh with tible ehydrogenase (αKGDH) (αKGDH) ehydrogenase like syndrome, or or in syndrome, like John Wiley& Sons obtained from the OMIM OMIM the from obtained y affect the structure, structure, the affect y in assay medium. AR = = AR medium. in assay

KDH) and *additional *additional KDH) and enes have been have enes ed with the MT prefix. prefix. the MT ed with Maternal Maternal Maternal Maternal Maternal AR AR AR AR AR AR AR AR AR Xlinked Inheritance

Complex IV IV Complex III Complex QCoenzyme II Complex 10 10

NDUFA4 MTCO3 BCS1L PDSS2 FOXRED1 NDUFAF6 NDUFAF5 NDUFAF2 NDUFA12 NDUFA10 NDUFA9 NDUFA2 NDUFA1 NDUFS8 NDUFS7 NDUFS4 NDUFS3 NDUFS2 NDUFS1 NDUFV2 NDUFV1 MTND6 MTND5 UQCRQ UQCRQ SDHAF1 SDHA

COX15 COX10 SURF1 AcceptedTTC19 Article

This article isprotected by copyright. All rights reserved. Assembly factor factor Assembly factorAssembly factorAssembly factor Assembly factor Assembly factor Assembly Assembly factor factor Assembly factor Assembly factor Assembly factorAssembly Subunit Subunit Subunit Subunit CoQ Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit 10 synthesis synthesis 42 42

Annals ofNeurology John Wiley& Sons AR AR Xlinked AR AR AR AR AR AR AR AR Maternal Maternal AR AR AR AR AR Maternal AR AR AR AR AR AR AR AR AR AR AR AR AR Page 42of58 Page 43of58 Mitochondrial Mitochondrial DNA Mitochondrial

translation translation maintenance affected Pathway &V IV III, I, Complexes deficiency Biochemical 1A continued: Table V Complex

NARS2 NARS2 IARS2 FARS2 EARS2 MTFMT MTTW MTTV MTTL1 MTTK MTTI POLG FBXL4 MTATP6 ETHE1 LRPPRC PET100 mtDNA deletion deletion mtDNA SUCLG1 SUCLA2 Gene TACO1 SCO2

Accepted TRMU GTPBP3 Article

This article isprotected by copyright. All rights reserved. Assembly factor factor Assembly factor Assembly Subunit Subunit detoxification Sulfide activator Translational stability mRNA Mitochondrial tRNA tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial synthesis Nucleotide synthesis Nucleotide tRNA modification modification tRNA - replication mtDNA (Unclear) function Protein tRNA aminoacylation aminoacylation tRNA aminoacylation tRNA aminoacylation tRNA aminoacylation tRNA modification tRNA modification tRNA 43 43 Annals ofNeurology John Wiley& Sons Maternal Maternal AR AR AR AR AR

Inheritance Inheritance AR AR AR AR AR AR AR AR Maternal Maternal Maternal Maternal Maternal Sporadic AR AR AR AR

Formatted: Left

deficiency deficiency Biotinidase deficiency PDHc enzyme ± OXPHOS deficiency biochemical Associated energy generation. imp secondary cause that genes disease LS 1B: Table

BTD BTD AIFM1 ECHS1 HIBCH PNPT1 Accepted SERAC1 Article Genes C12orf65 TSFM GFM2 GFM1

This article isprotected by copyright. All rights reserved. Biotin recycling recycling Biotin factor/apoptosis Assembly remodeling Phospholipid import RNA Mitochondrial release peptide Mitochondrial recycling Ribosome Valine catabolism catabolism Valine catabolism Valine function Protein elongation Translation elongation Translation 44 44 Annals ofNeurology John Wiley& Sons airment of mitochondrial mitochondrial of airment

AR AR AR Inheritance AR AR AR AR AR AR AR Xlinked AR Formatted: Pattern: Clear Pattern: Page 44of58 Page 45of58 be offered treatment for symptoms such as acidosis, as such symptoms for treatment be offered

Pyruvate dehydrogenase deficiency ( deficiency dehydrogenase Pyruvate ( Biotinidase deficiency ( TPK deficiency ( disease ganglia basal Biotin/thiamineresponsive ( encephalopathy Ethylmalonic QCoenzyme formbiochemical Gene or anesthesia. mana aggressive nutrition, good ensure to important to treatment. respond that can forms biochemical sy Leigh for options therapeutic 2: Available Table 113 10 10

deficiency (deficiency

Accepted ArticleTPK1 ) ) BTD

PDSS2

Biotin ) ETHE1) ETHE1) ) Coenzyme Q Coenzyme ) This article isprotected by copyright. All rights reserved. PDHA1 ) Thiamine and highfat diethighfat and Thiamine ) 45 45 SLC19A3) SLC19A3) , dystonia or cardiomyopathy. It is also is It also or cardiomyopathy. dystonia seizures, gement of intercurrent illnesses and caution with with caution and illnesses of intercurrent gement Apart from targeted therapies, all LS patients can LScan patients all therapies, targeted from Apart Annals ofNeurology ndrome patients, and the genetic and and genetic the and patients, ndrome John Wiley& Sons Thiamine and high dose biotinhigh dose and Thiamine Thiamine Thiamine Treatment Metronidazole and Nacetylcysteineand Metronidazole

10

SUCLA2 SUCLA2 ETHE1 PET100 SCO2 LRPPRC SURF1 NDUFS4 defect defect biochemical Gene and reported). featur syndromedisease Leigh 3: Characteristic Table

CI, III, IV &V Methylmalonic aciduria, dystonia, de dystonia, aciduria, Methylmalonic petechiae, acrocyanosis, aciduria, Ethylmalonic IV &V III, CI, Seizures CIV spinalat muscular cardiomyopathy, Hypertrophic CIV pathologya and liver dysmorphism, facial Mild CIV cognitive sparing Hypertrichosis, CIV by year death LSwith course 3 disease ‘Typical’ CIV CI features disease Characteristic in skeletal muscle skeletal muscle in Accepted decompensation metabolic acute Article

es, affected ethnicities and founder genotypes asso genotypes founder ethnicities and affected es,

afness, often Leighlike presentation, Faroese Isla Faroese oftenLeighlike presentation, afness, This article is protected by copyright. All rights reserved. gastrointestinal involvement Mediterranean a basin Mediterranean gastrointestinal involvement course punctuated by episodes of by episodes punctuated course s Ashkenazi Jews c.462delA with an estimated freque with estimated an c.462delA Jews Ashkenazi s rophy pattern of histopathology rophypattern 46 Annals ofNeurology John Wiley &Sons ciated with the most common nuclear disease genes( disease common nuclear the most ciated with Ethnicities notably affected notably Ethnicities Arabian peninsula regions regions peninsula Arabian eaee c.3G>C Lebanese Caucasian in c.311_312insATdel10 (Panethnic) (Panethnic) region of Quebec, Canada of regionQuebec, SaguenayLacSaintJean nders c.534+1G>A with an estimated carrier carrier estimated with an c.534+1G>A nders nd nd Founder / frequent frequent /genotypes Founder c.487C>T, p.R163Wc.487C>T, of1:1000 Europeans c.1541G>A, p.E140K c.1541G>A, estimated carrier frequency of 1:23frequencyofcarrier estimated anwith p.A354V c.1119C>T, 114 25,113

35

all with ≥ 10 ≥patients 10 all with 38 39

3,37 ncy

Page 46of58 Page 47of58 PDHX PDHX PDHA1 SERAC1 MTFMT

PDHc Lactate:pyruvate ratio <20, agenesis ofcorpus agenesis <20, ratio Lactate:pyruvate behaviora liverinvolvement, , PDHc Multiple observed frequently Microcephaly IV &V III, CI, PDHc Lactic acidosis crisis in newborn or early in newborn in crisis Lactic acidosis PDHc

presentation presentation cerebral atrophy, onset in early infancy with long with early ininfancy onset atrophy, cerebral

Accepted Article

This article is protected by copyright. All rights reserved. infancy, cerebral palsylike cerebral infancy, l disturbance (Panethnic) (Panethnic) ldisturbance callosum frequently observed (Panethnic) (Panethnic) observed frequently callosum disease duration duration disease 47 Annals ofNeurology John Wiley &Sons Roma children from Bulgaria c.1336C>T, p.R446* c.1336C>T, Bulgaria from children Roma Europeans c.626C>T with an estimated carrier carrier estimated anwith c.626C>T Europeans frequency of ~1:33 peopleof~1:33 frequency frequency of 1:100 in Europeansin of1:100 frequency 116

4 , 115

51

Accepted Article

This article isprotected by copyright. All rights reserved. 170x83mm (300170x83mm 300DPI) x Annals ofNeurology John Wiley& Sons

Page 48of58 Page 49of58

Accepted Article

This article isprotected by copyright. All rights reserved. 170x92mm (300170x92mm 300DPI) x Annals ofNeurology John Wiley& Sons

Accepted Article

This article isprotected by copyright. All rights reserved. 170x113mm(300 300DPI) x Annals ofNeurology John Wiley& Sons

Page 50of58 Page 51of58

Complex III III Complex Q Coenzyme II Complex I Complex dehydrogenase Pyruvate deficiency Biochemical product. geneeach of role the on information Tabl Supplementary inheritance. recessive autosomal by inheritance deletionmtDNA = mtDNA syndr Leigh cause mutations which in 1: Genes Table Biotinidase Biotinidase PDHc ± OXPHOS mi of impairment secondary cause that genes Disease V Complex IV Complex Mitochondrial DNA Mitochondrial Mitochondrial Mitochondrial maintenance Combined OXPHOS defects Pathway affected affected Pathway defects OXPHOS Combined

Accepted translation Article

10 10

* , ^ indicates sporadic inheritance; all other genes are genes other all inheritance; sporadic indicates This article isprotected by copyright. All rights reserved. NDUFS7 MTATP6 NDUFS1NDUFV2, NDUF1V, MTND1 LRPPRC NDUFA12 PDHA1 MTCO3 PDSS2 SLC19A3 UQCRQ, BCS1L, TTC19BCS1L, UQCRQ, SDHA FBXL4 BTD AIFM1SERAC1, ECHS1, HIBCH, MTFMT, mtDNA GFM1 . . , , Xlinked inheritance indicated by by indicated inheritance Xlinked

SDHAF1 # * * , PDHB , , , , , , , * , , , ,

, ,

MTND NDUFA4 GFM2 TACO1, ETHE1 TACO1, NDUFS8 , , SLC25A19 POLG

NDUFAF2 ^ GTPBP3 , , Annals ofNeurology MTTI John Wiley& Sons , ,

, 2 , , PDHX TSFM, C12orf65, TSFM, * SUCLA2 , , , , * , , MTND3 , , NDUFA1 SURF1 , ,

MTTK TRMU, EARS2 TRMU, , , NDUFAF5 , ,

DLAT

, , , , * * SUCLG1 , , COX10

Genes Genes MTTL1 # MTND4 , , tochondrial energy generationenergy tochondrial ome or Leighlike syndrome. syndrome. Leighlike or ome e 1 contains additional additional contains 1 e NDUFS2 , NDUFA2 DLD ,

PNPT1 NDUFAF6 , , # , *

COX15 , , FARS2 , *

, , LIPT1 MTTV MTND5 , , , NDUFS3 # NDUFA9

, maternal , , , , , , , * associated with with associated IARS2, NARS2 IARS2, SCO2 , LIAS , ,

MTTW FOXRED1 * , MTND6 , , , , , , , NDUFS4 TPK1 PET100 NDUFA10 * ,

* , ,

, , , , , , , ,

, ,

( deficiency dehydrogenase Pyruvate ( deficiency Biotinidase ( deficiency TPK ( disease ganglia basal Biotin/thiamine-responsive encephalo Ethylmalonic QCoenzyme form biochemical or Gene anesthesia. mana aggressive nutrition, good ensure to important se acidosis, as such symptoms for treatment offered treatment. to canrespond that forms biochemical sy Leigh for options therapeutic 2:Available Table 113

10 10 Accepted Article

deficiency (deficiency TPK1 ) ) BTD pathy ( pathy This article isprotected by copyright. All rights reserved. PDSS2

Biotin ) ETHE1) )

PDHA1

Annals ofNeurology John Wiley& Sons )

SLC19A3) SLC19A3) izures, dystonia or cardiomyopathy. It is also It is cardiomyopathy. or dystonia izures, gement of intercurrent illnesses and caution with with caution and illnesses of intercurrent gement Apart from targeted therapies, all LS patients can can patients LS all therapies, targeted from Apart ndrome patients, and the genetic and genetic the and patients, ndrome Thiamine Thiamine Metronidazole and Nand Metronidazole Q Coenzyme Treatment Thia Thiamine and high dose biotin dose high and Thiamine mine and high mineand

10

- fat diet fat - acetylcysteine

be be Page 52of58 Page 53of58 MTFMT MTFMT SUCLA2 ETHE1 PET100 SCO2 LRPPRC SURF1 NDUFS4

defect defect biochemicaland Gene reported). feat disease syndrome Leigh Characteristic 3: Table

CI, III, IV &V Microcephaly frequently observed observed Microcephaly frequently III,IV&V CI, petechiae, acrocyanosis, aciduria, Ethylmalonic Seizures CIV at spinalmuscular Hypertrophic cardiomyopathy, CIV pathologyand a liver dysmorphism, Mild facial CIV sparing cognitive Hypertrichosis, CIV year3by course death with disease LS ‘Typical’ CIV CI

Accepted dedystonia, aciduria, Methylmalonic III,IV&V CI, Article

in skeletal muscle in skeletal cerebral atrophy, onset in early infancy with long long with infancy earlyonset atrophy, in cerebral involvement,chronic involvement,chronic disease features Characteristic acute metabolic decompensation decompensation metabolic acute

ures, affected ethnicities and founder genotypes as ethnicitiesandgenotypes affected founder ures, This article is protected by copyright. All rights reserved.

afness, often Leigh-like presentation, oftenLeigh-like afness,

gastrointestinal course punctuated by episodes of episodes by punctuated course s Ashkenazi Jews c.462delA with an estimated freque anestimated with c.462delA Jews Ashkenazi s rophy pattern ofhistopathology pattern rophy disease duration duration disease Annals ofNeurology John Wiley &Sons sociated with the most common nuclear disease genes disease most common nuclear the with sociated Ethnicities notably affected affected notably Ethnicities Arabian peninsula regions regions peninsula Arabian and basin Mediterranean (Pan-ethnic) Faroese Islanders c.534+1G>A with an estimated carr estimated with an c.534+1G>A Islanders Faroese region of Quebec, Canada Canada of Quebec, region Saguenay-Lac-Saint-Jean Europeans c.626C>T with an estimated carrier estimated carrier an with c.626C>T Europeans c.3G>C Lebanese Caucasian in c.311_312insATdel10 (Pan-ethnic) Founder / frequent genotypes /frequent Founder c.487C>T, p.R163W c.487C>T, c.1541G>A, p.E140Kc.1541G>A, frequency of ~1:33 people of~1:33 frequency estimated carrier frequency of 1:23of frequency estimatedcarrier an with p.A354V c.1119C>T, Europeans of 1:1000of 114 25,113 25,113

35

(all with ≥ 10 ≥ patients with (all 38 39

4,115

3,37 ncy ier ier

PDHX PDHX PDHA1

SERAC1 SERAC1

PDHc Lactate:pyruvate ratio <20, agenesis of agenesis corpus <20, ratio Lactate:pyruvate PDHc PDHc Lactic acidosis crisis in newborn or inearly newborn crisis in acidosis Lactic PDHc

Accepted Article behaviora involvement, liver Hypoglycemia, Multiple

presentation presentation

This article is protected by copyright. All rights reserved. infancy, cerebral palsy-like infancy, cerebral itrac Pnehi) - (Pan-ethnic) disturbance l clou rqetyosre (a-tnc - (Pan-ethnic) observed frequently callosum Annals ofNeurology John Wiley &Sons Roma children from Bulgaria c.1336C>T, p.R446* c.1336C>T, Bulgaria from Roma children frequency of 1:100 in Europeans1:100of in frequency 116

Page 54of58 51

Page 55of58 Complex I I Complex dehydrogenase Pyruvate deficiency Biochemical gene. each for entry be can references Appropriate recessive. autosomal (TPP) pyrophosphate thiamine of absence in observed system. enzyme cleavage glycine the of deficiency (BC dehydrogenase alphaketoacid chain branched and # denot are genes DNAencoded Mitochondrial syndrome. iscompa that presentation a reported with patients Leigh or Leigh with diagnosed patients in described in mutations Pathogenic enzymes. and OXPHOS (PDHc) p the of activity or stability assembly, structure, Supplementary Accepted Article d alphaketoglutarate of deficiency additional with

Table 1A: Leigh syndrome disease genes that directl that genes disease syndrome Leigh 1A: Table

LIAS* LIAS* DLD DLAT PDHX PDHB PDHA1 LIPT1 MTND4 MTND4 MTND3 MTND MTND1 TPK1 SLC25A19 SLC19A3 Gene Gene # † # #

2 2 This article isprotected by copyright. All rights reserved.

†

†

Subunit Subunit Subunit Subunit Subunit Co-factor transporter Co-factor transporter Co-factor synthesis Co-factor synthesis Co-factor attachment Co-factor Subunit Subunit protein binding Subunit Subunit Subunit function Protein Annals ofNeurology John Wiley& Sons

yruvate dehydrogenase complex complex dehydrogenase yruvate † PDHc deficiency only only deficiency PDHc tible with Leigh or Leighlike Leighlike orLeigh with tible ehydrogenase (αKGDH) (αKGDH) ehydrogenase like syndrome, or in in or syndrome, like obtained from the OMIM OMIM the from obtained in assay medium. AR = AR medium. assay in

KDH) and *additional and*additional KDH) ed with the MT prefix. prefix. MT the with ed these genes have been been have genes these Maternal Maternal Maternal Maternal Maternal AR AR AR AR AR AR AR AR AR AR X Inheritance - linked y affect the the affect y

Complex IV IV Complex III Complex Q Coenzyme II Complex

Accepted 10 Article

MTND5 MTND6 FOXRED1 NDUFAF6 NDUFAF5 NDUFAF2 NDUFA12 NDUFA10 NDUFA9 NDUFA2 NDUFA1 NDUFS8 NDUFS7 NDUFS4 NDUFS3 NDUFS2 NDUFS1 NDUFV2 NDUFV1 NDUFA4 MTCO3 PDSS2 BCS1L COX15 COX10 SURF1 UQCRQ UQCRQ SDHAF1 SDHAF1 SDHA TTC19

This article isprotected by copyright. All rights reserved.

Assembly factorAssembly Assembly factor factor Assembly factor Assembly factor Assembly Assembly factorAssembly factor Assembly Assembly factorAssembly factor Assembly factor Assembly factor Assembly Subunit Subunit Subunit CoQ Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit Subunit 10 Annals ofNeurology synthesis synthesis John Wiley& Sons

AR AR AR AR AR Maternal AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR X-linked AR AR AR AR AR AR AR AR Maternal Maternal AR AR AR

Page 56of58 Page 57of58 Mitochondrial Mitochondrial DNA Mitochondrial

translation translation maintenance affected affected Pathway &V IV III, I, Complexes deficiency Biochemical Supplementary V Complex

Accepted Article

Table 1A continued: continued: 1ATable

POLG FBXL4 MTATP6 PET100 LRPPRC ETHE1 MTFMT MTTW MTTV MTTL1 MTTK MTTI NARS2 NARS2 IARS2 FARS2 EARS2 SUCLG1 SUCLA2 TACO1 mtDNA deletion deletion mtDNA TRMU TRMU GTPBP3 Gene Gene SCO2

This article isprotected by copyright. All rights reserved.

Assembly factor factor Assembly factorAssembly Sulfide detoxification detoxification Sulfide activator Translational stability mRNA Subunit Mitochondrial tRNA tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial tRNA Mitochondrial Nucleotide synthesis synthesis Nucleotide synthesis Nucleotide tRNA aminoacylation aminoacylation tRNA aminoacylation tRNA aminoacylation tRNA aminoacylation tRNA modification tRNA modification tRNA modification tRNA - mtDNA replication replication mtDNA (Unclear) function Protein Annals ofNeurology John Wiley& Sons

Maternal AR AR AR AR AR

AR AR AR AR AR AR AR AR Maternal Maternal Maternal Maternal Maternal Sporadic Inheritance Inheritance AR AR AR AR AR

Accepted deficiency Biotinidase deficiency Article enzyme PDHc ± OXPHOS deficiency biochemical Associated generation. energy mitochondrial Supplementary

Table 1B: LS disease genes that cause secondary imp secondary cause genes that disease LS 1B: Table

BTD AIFM1 AIFM1 ECHS1 HIBCH PNPT1 PNPT1 SERAC1 SERAC1 Genes Genes C12orf65 TSFM GFM2 GFM1

This article isprotected by copyright. All rights reserved.

Biotin recyclingBiotin import RNA Mitochondrial release peptide Mitochondrial recycling Ribosome Assembly factor/apoptosis factor/apoptosis Assembly remodeling Phospholipid Translation elongation elongation Translation Valine catabolism catabolism Valine catabolism Valine Translation elongationTranslation Protein function function Protein Annals ofNeurology John Wiley& Sons

Inheritance Inheritance AR AR AR AR AR AR X-linked X-linked AR AR AR airment of of airment

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