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European Journal of Endocrinology -19-0119 Medicine Programme,GeneticsandEpigeneticsinHealthDiseaseSection,UCLGreatOrmondStreetInstituteof Canada, The HospitalforSickChildren,Toronto,Canada, Great OrmondStreetHospitalforChildrenNHSFoundationTrust,London,UK, Trust, London,UK, Düsseldorf, Germany, 1 Sebastian Kummer Emma Clement Alena Welters in childrenwithRubinstein–Taybisyndrome Persistent hyperinsulinaemichypoglycaemia the neonatalperiodandearly infancy( is themostcommonformof persistenthypoglycaemiain glucose concentrations( of insulinfrompancreatic beta cellsdespitelowblood episodes of hypoglycaemia due to the dysregulated release heterogeneous disordercharacterizedbyrecurrent Hyperinsulinaemic hypoglycaemia(HH)is a Introduction diagnosis. infants withRSTS.InchildrenanapparentsyndromicformofHH,RSTSshouldbeconsideredinthedifferential these twoconditions.WethereforerecommendthatcliniciansshouldbevigilantinscreeningforHHsymptomatic Conclusions: treatment withdiazoxide,octreotideandnifedipine,butrespondedtosirolimus.Allrequiredgastrostomyfeeding. choanal atresiaorstenosis.DiagnosisofHHvariedfrom1 dayto18 monthsage.Onepatientwasunresponsive a panelofgenesassociatedwithnon-syndromicHH.TwopatientshadclassicmanifestationsRSTS,three Results: Clinical characteristics,metabolicprofileduringhypoglycaemiaandtreatmentwerereviewed. Methods: Design: brain injury. one ofthepossiblecausespersistentHH.EarlydiagnosisandtreatmentHHiscrucialtopreventhypoglycaemic hypoglycaemia (HH).SeveralsyndromesareassociatedwithHH.WereportRubinstein–Taybisyndrome(RSTS)as Objective: Abstract Child Health,London,UK Department ofGeneralPaediatrics,NeonatologyandPaediatricCardiology,Medical Faculty,UniversityChildren’sHospitalDüsseldorf, https://doi.org/ https://eje.bioscientifica.com Clinical Study 7 FourRSTSpatientswithHHwereretrospectivelyanalysed. Disease-related Division ofEndocrinology,TheHospitalforSickChildren,Toronto,Canada, and Geneticinvestigationsincludednext-generationsequencing-basedgenepanelsandexomesequencing. Geneticaetiologyremainsunknowninupto50%ofpatientswithpersistenthyperinsulinaemic 10.1530/EJE GiventherarityofRSTS(1:125 000)andHH(1:50 000),ourobservationsindicateanassociationbetween 3 1 Center forHumanGenetics,Bioscientia,Ingelheim,Germany, , Ranna El-Khairi 4 , Jane A Hurst 2 Endocrinology Department,GreatOrmondStreetHospital forChildrenNHSFoundation -19-0119 1 EP300 1 ). Althoughararedisorder, HH 2 © or 2019EuropeanSociety ofEndocrinology 4 , Nada Quercia A Weltersandothers CREBBP 2 , Antonia Dastamani 6 Department ofMolecularGenetics, UniversityofToronto, 2 ). variantswerefoundinallpatients,nopathogenic Printed inGreatBritain 5 , 6 , Jonathan D Wasserman 2 , Nadine Bachmann 5 morphologically heterogeneous disorders. It can be ( cornerstone forimprovingneurodevelopmental outcomes Therefore, earlyrecognition andtreatmentofHHisthe and seizures ( such as permanent brain injury brain areassociatedwithseriouslifelongcomplications hypoglycaemia Rubinstein–Taybi syndromeand Department ofGeneticCounselling, 6 Published byBioscientifica Ltd. 4 ). HHrepresentsagroupof clinically, geneticallyand Department ofClinicalGenetics, Recurrent hypoglycaemicinsultstothedeveloping 8 Genetics andGenomic 7 , Thomas Meissner 3 , Carsten Bergmann Downloaded fromBioscientifica.com at09/24/202106:30:18PM (2019) Endocrinology European Journalof uni-duesseldorf.de sebastian.kummer@med. [email protected] Email to PShah or S Kummer should be addressed Correspondence 1 , Pratik Shah 181 181 3 , Clare Gilbert :2 , 121–128

121 3 , 2 –128 , 8

4 and or , 2 5 , via freeaccess ). European Journal of Endocrinology https://eje.bioscientifica.com de novo in individuals withRSTSandHHduetopathogenicvariants More recently, Lopez A geneticdiagnosisforthispatientisnotavailable. production rateofSGAinfantstomaintaineuglycemia. glucose infusionattwicethenormalendogenous gestational age(SGA)newbornwithRSTSthatrequired a al et for anassociationbetweenRSTS andHH. phenotype of these patients and increasing the evidence information ontheclinical characteristics andmetabolic of fourRSTSpatientswith HH,providingadditional syndromic causeofpersistentHH( been published,RSTShas not yetbeen recognized asa single reportsofhypoglycaemiainRSTSpatientshave approximately 20–30%ofcases( in upto10%ofpatients.Thegeneticcauseisunknown variants disruptingtheparalogousgene haploinsufficiency ofthe P300). Themajorityofcases(60–70%)arecausedby CBP) andofE1A-bindingproteinP300( protein (CREB)-binding( RSTS, i.e.thoseofthecAMPresponseelement-binding Pathogenic variantsintwogenesareknowntocause may bepresentinupto30%ofRSTSpatients( tractanomaliesand epilepsy cardiovascular or urinary range ofcognitiveimpairment.Comorbiditiessuchas facial appearance,distallimbabnormalitiesandabroad by postnatalgrowthdeficiency, microcephaly, typical RSTS isararedevelopmentaldisordercharacterized summarize theclinicalcourseoffouraffectedpatients. syndrome (RSTS) and persistent HH, andsystematically provide informationonprognosisandrecurrencerisk. diagnosis is important to guide medical management and outcomes ofthesechildren.Moreover, anearlygenetic of HHandfurtherimpairtheneurodevelopmental co-existing diagnosisofHH.Thismaydelaythe conditions mayleadtodifficultyinrecognisinga syndrome ( abnormalities such asTurner syndromeand Patau congenital disordersofglycosylationandchromosome failure syndromessuchasCostelloandKabukisyndrome, syndrome (BWS) and Sotos syndrome, postnatal growth overgrowth syndromessuchasBeckwith–Wiedemann at least20differentraregeneticsyndromes,whichinclude insulin secretionbuthasalsobeenreportedasafeaturein caused by pathogenic variants in key genes regulating Clinical Study EP300 We reviewtheclinical courseandgeneticfindings We heredescribetheassociationofRubinstein–Taybi . reportedacaseoftransientHHinsmallfor missensevariantintheHAT domainof (deletionofexons12–21 7 , 8 , 9 , 10 ). Thecomplexityofsomesyndromic et al . andCostain CREBBP 11 A Weltersandothers , gene.Heterozygous 12 EP300 15 , CREBBP- 13 et al , EP300 EP300 16 , ; heterozygous 14 . reportedon , ). Although 17 arefound -encoding EP300 encoding ). Wyatt ). 11 ). structurally normalhearton echocardiogram.MRIbrain ECG recordingsandsmall pericardialeffusionwith and bradycardiawithnormal sinusrhythmon24-h micro-aspirations. Shealso had episodesoftachycardia disease (GORD)withunsafe swallowresultinginsilent developmental delayandgastro-oesophagealreflux requiring nasalstentinsertionintheneonatalperiod, Other clinicalfeaturesincludedbilateralchoanalatresia time suggestiveofanunderlyingsyndromicdiagnosis. features outofkeepingforageandethnicitybutnotatthat birth weightof2600 Individual 1(P1)wasbornat38-weeksgestation,with a Case 1 summarized in investigations and treatment regime of all individuals are Clinical characteristics,metabolicprofile,genetic Results to preventhypoglycaemia defined astheamountofcarbohydratesinitiallyrequired as FFA were negative.Lowfreefattyacids(FFA) weredefined hydroxybutyrate levelwas was definedashypoketotichypoglycaemiawhenbeta- during hypoglycaemia ketones and c-peptide,freefattyacidsbloodorurinary Metabolic profilingincludedthemeasurementofinsulin variants wereclassifiedaccordingtoACMGcriteria( was arranged due to the clinical suspicion of RSTS. Sequence cases otherthancase2wheretargetedtestingof congenital hyperinsulinism(CHI)wereexcludedinall applied. Pathogenicvariantsingenesassociatedwith (NGS)-based genepanelsorexomesequencingwere syndromes wasnegative,next-generationsequencing features wereprevailingandtargetedtestingforspecific the predominantfeature.WhenHHand/orotherclinical disorders (DDD)studywhendevelopmentaldelaywas or untargetedaspartofthedecipheringdevelopmental in investigations were eithertargeted for pathogenic variants from allpatientsortheirrespectiveguardians.Genetic for publicationoftheirclinicaldetailswasobtained were retrospectivelyanalysed.Written informedconsent Four patientswithgeneticallyconfirmedRSTSandHH Patients andmethods hypoglycaemia Rubinstein–Taybi syndromeand EP300 < and mlL ( 1.7 mmol/L CREBBP Table 1 when RSTS was clinically suspected g ( 19 . Downloaded fromBioscientifica.com at09/24/202106:30:18PM − ). Initialglucoserequirementis 1.2 SDS).Shehadsubtlefacial ≤ < < mlL Hypoglycaemia 2.7 mmol/L. 3.5 mmol/L. 1.8 mmol/L orurineketones 181 :2 CREBBP 122 18 via freeaccess ).

European Journal of Endocrinology percutaneous gastrostomy. ASD, atrialseptaldefect;DZX,diazoxide; GORD,gastro-oesophagealrefluxdisease;NIF,nifedipine;OCT,octreotide; PDA,patentductusarteriosus;PEG, *Including ABCC8,KCNJ11,GCK,GLUD1, HADH,HNF1A,HNF4A,SLC16A1,UCP2. Medication Fasting tolerance Feeds Current managementofHH Age atpatient’slastclinic PEG feeds Feeds Feeding regimeatdischarge(afterdiagnosisofHH) PEG feedings HH medication-related Sirolimus OCT NIF DZX HH medications(initialdosage) Initial glucose Mutation inknownCHI Scan Additional investigationsrelatedtoHH Pathogenic mutation Free Fattyacids Hypoketotic C-peptide, pmol/L Insulin, pmol/L Glucose, mmol/L Metabolic profileduringhypoglycaemia Age atdiagnosisofHH Age atdiagnosisofRSTS Developmental delay Other clinicalfeatures Dysmorphic features Sex Birth weight(g) Gestational age(w) persistent HH. Table 1 Clinical Study visit (years) severe sideeffects requirements genes Clinical characteristics,metabolicprofile,geneticinvestigationsandtreatmentregimeoffourRSTSpatientswith 11 h Overnight PEGfeeds 3.9 Continuous overnight Daytime bolus Yes Sirolimus: sepsis Responsive (5 mg/m Unresponsive Unresponsive Unresponsive n.d. None* 18F-DOPA PET/CT: Heterozygous Low Yes N/A 27 2.3 1.54 years 2.38 years Yes Bilateral choanalatresia, mild non-specific Female 2600 38 Patient 1 day) diffuse uptake p.(His1255Arg) in c.3764A missense mutation sphenoid wing cyst atorbitalroof/ bradycardia, dermoid tachykardia and GORD, episodesof dysmorphic features > A Weltersandothers G, G, de novo EP300 2 /

Normal feeding, acarbose 7.87 Continuous dayandnight Yes DZX: fluidoverload Unresponsive Response uncleardueto 12 mg/kg/min none specific Heterozygous frameshift Low Yes 612 36 1.6 Day 1oflife < Yes GORD, undescended typical facialappearance Male 2660 38 Patient 2 1 months cataract, PDA testes, laryngomalacia, of RSTS postprandial HH because of malcompliance parental CREBBP p.(Glu349Lysfs*5) in mutation c.1044delT,

hypoglycaemia Rubinstein–Taybi syndromeand n.d. 154 2.2 Day 5oflife 4.5 years Yes Choanal stenosis, typical facialappearance Female 2985 38 Patient 3 DZX: 7.5 mg/kg/day 11–15 h 4.8 Continuous overnight Yes None Responsive ( > None* Heterozygous Low Yes 8 mg/kg/min 1c, shortstature tricuspid atresiatype of RSTS day) EP300 p.(Pro1502Leu) in c.4505C missense mutation

> T, < 5 mg/kg/ de novo Downloaded fromBioscientifica.com at09/24/202106:30:18PM

n.d. 39 2.1 1.42 years 1.58 years Moderate expressivespeech Bilateral choanalatresia, partialfacialappearanceof Female 2400 36 Patient 4 DZX: 6 mg/kg/day Bolus PEGfeedatbedtime 4 Continuous overnight Daytime bolus Yes DZX: fluidoverload Responsive (10.6 mg/kg/day) n.d. None* Heterozygous Low Yes https://eje.bioscientifica.com delay anomaly cyst, queryMüllerian recurrent smallhymenal conductive hearingloss, the asc.aorta,mild kidney, ASD,dilatationof multicystic dysplastic GORD, unilateral RSTS in c.4783T missense mutation EP300 181 :2 >

G, p.(Phe1595Val) de novo

123 via freeaccess European Journal of Endocrinology https://eje.bioscientifica.com with lowbloodglucoseof0.9 of lifeandonday2hehada generalizedseizureassociated ( consanguineous parentswith abirthweightof2660 gestation to non- Individual 2 (P2) was born at 38 weeks Case 2 < of 11 adequate calories).Fastingtestrevealedafastingtolerance feeds andondemandduringdaytime(toprovide successfully tolerated4–6 c.3764A identification ofalikelypathogenicvariantin followingthe a diagnosisofRSTSwasmadeat2.4 years 21 introduced intoherdiet. regime. Thickenedliquidsandpureedfoodweregradually andshewasmanagedwithanintensivefeeding 2.6 years (sepsis). Consequently, sirolimuswasstoppedattheageof response, butlaterdevelopedseveresystemicinfection 5 mg/m tried onsirolimus(mTORinhibitor)therapy(maximum doses ofdiazoxide,octreotideandnifedipine.Shewas 18 18 KCNJ11 negative forknownnon-syndromiccausesofHH( for furthermanagementofHH.Genetictestingwas hypoglycaemia andwastransferredtoaspecialistcentre overnight. However, she continued to have episodes of during thedaytimeandcontinuousgastrostomyfeeds unsafe swallow. She was fed with frequent bolus feeds the management of HH, along with severe GORD and A percutaneous gastrostomywasalsoinserted,aspartof the doseof5 HH ( biochemical investigationsconfirmedthediagnosisof seizures following an episodeofhypoglycaemia. Further yearsandhadgeneralizedtonicclonic the ageof1.5 conduction. peripheral nerve conductionstudiesshowedminorabnormalitiesof nerve with adermoidcystwasseen.Electromyographyand related totheleftsphenoidwingororbitalroof,consistent axis.Awell-definedcysticlesion hypothalamic pituitary showed normalintracranialappearancesincludingthe − 14 pmol/L). F-DOPA. Thepatientwasunresponsivetomaximum F-DOPA-PET/CT scansuggesteddiffuseuptakeof Clinical Study 1.2 SDS).P2wasnoticedto have poorfeedingonday1 ) to try tounderstandthecauseofherdifficultiesand ) totry thrls lncrve tteaeo . yearsshe At herlastclinicreviewattheageof3.9 This individual was recruitedtotheDDDproject( She hadrecurrentepisodesofhypoglycaemiafrom Table 1 h (blood glucose 2.9 2 , > /day), to whichshe demonstrated a good GCK G p.His ). Shewasthencommencedondiazoxideat , mg/kg/day andchlorothiazide7 GLUD1 1255Arg. , HADH hourly overnightgastrostomy mmol/L, undetectable insulin , HNF1A mmol/L. Hewasadmitted A Weltersandothers , HNF4A , mg/kg/day. SLC16A1 ABCC8 EP300 20 ). g , ,

hypoglycaemia andhisscreenshowed (EEG) didnotshowthepresenceofepileptiformactivity. changes anddelayedmyelination.Electroencephalogram and CT, whichshowedsomenon-specificwhitematter ofseizure-like episodes, hehadabrainMRI a history ductus arteriosuswhichclosedspontaneously. Dueto leftanteriorpolarcataractandapatent laryngomalacia, findings includedbilateralundescendedtestes,mild broad andangulatedthumbshalluces.Other intolerance. ofcow’sformula duetoafamilyhistory milkprotein Feeds weresubsequentlychangedtoanaminoacid-based started onanti-refluxmedications inthefirstweekoflife. to anapnoeicepisodeandwasdiagnosedwithGORD feeding difficulties,includingchokingepisodes,leading regular feedsandintravenous fluids. Hewasnotedtohave to theneonatalunitandhypoglycaemiawasmanagedby gradually triedonsmallbolus feedsattheageof4.0 years discharged homeon24-h continuousfeeds.Hewas improvement inhisblood glucose levels.Hewasthen He also had a trial of nifedipine but did not show any keen tocontinuedueits side effectsofhypertrichosis. was madetostopthediazoxideasparentswerenot continued tohavehypoglycaemicepisodesandadecision kg/day) alongwith2-hourlybolusfeeds.However, he via gastrostomyandslowbolusfeeds. containing meals).Hewastreatedwithcontinuousfeeds secretion in response toglucoseingestion (carbohydrate of hishypoglycaemiaisrelatedtosurgesininsulin insulin 78.5 presence ofinsulinfollowingOGTT(glucose2.5 post prandialhypoglycaemiawithaninappropriate ofage.Hedeveloped Nissens fundoplicationat8 months a A bariumstudyconfirmedGORDandheunderwent video fluoroscopyshowedpoorsuckandunsafeswallow. He hadpersistentvomitingoncontinuous feeds and glucose 4.2 and wasmanagedonregularhighcaloriefeeds(blood months, he fasted for 6 feeds and at the age of 2.5 the managementofHH.Hewasmanagedonregular 46, the patient was transferred to a specialist centre for a fewdayslaterduetosignsoffluidoverload.Onday was startedondiazoxideday38,butthisstopped min) inordertomaintaineuglycaemia.Subsequently, he ketones). He had high glucose requirements (12 36 hypoketotic HH(bloodglucose1.6 hypoglycaemia Rubinstein–Taybi syndromeand pmol/L, C-peptide612 He continuedtohaveintermittentepisodesof He wasalsonotedtohavecoarsefacialfeatures, He wasgivenanothertrialofdiazoxide(upto10 mmol/L, undetectableinsulin pmol/L). Thissuggestedthatthemechanism Downloaded fromBioscientifica.com at09/24/202106:30:18PM pmol/L, negativeurine 181 mmol/L, insulin :2 < 14 pmol/L). mmol/L, mg/kg/ 124 mg/ via freeaccess h European Journal of Endocrinology to 1.4 continuous overnight feeding via PEG (stepwise decreased 4–5 day) inadditiontogivingdaytime mealsevery achieved by low-dose diazoxide treatment (2.2 and psychomotor difficulties. Glycaemic control was choanal stenosiswerenoted,aswellcoarsewrists with thinupperlip,ptosis,intermittentstrabismusand long eyelashes,leftearauriculardysplasia,philtrum Facial features such as abeakednose, arched eyebrows, ( body weightwas13.3 gastric tube(PEG)feedingovernight. frequent daytimefeedsandcontinuouspercutaneous was managedwithlow-dosediazoxide(2.5 ofage,HH increased. Athospitaldischargeat6 months kg/day, althoughcarbohydraterequirementswerestill unclear reasons diazoxide was not titrated above 5 leading toimprovedglycaemiccontrol.However, for age, diazoxidetreatment( of FFA, thus leading to the diagnosis of HH. At 6 weeks (154 and249 evaluations showedinappropriateinsulinsecretion During hypoglycaemia ( requiring observed circulation. that wassurgicallymanaged,laterresultinginFontan diagnostic evaluationsrevealedtricuspidatresiatypeIc noted atbirthrequiringintensivecaretreatment.Further palate, dysmorphicfeaturesandcentralcyanosiswere SDS) andheadcircumference 31.8 birth weightwas2985 gestation to healthy, non-consanguineous parents. Her weeksof The thirdindividual(P3)wasbornat38 Case 3 CREBBP pathogenic variantc.1044delT, 1.17 mmol/L). < the fast(bloodglucose4.1 tolerance of18 of postprandialhypoglycaemiawithagoodfasting feeding regime.Hecontinuestohaveoccasionalepisodes acarbose (25 on day) with his bolus feeds. He is currently 7.87 years, and wascommenced on acarbose(25 − 14 Clinical Study 3.2 SDS) and head circumference 45.5 At first admission to a HH specialist service at4.3 years,At firstadmissiontoaHHspecialistservice Since day5oflife,recurrenthypoglycaemiawas His geneticinvestigationsconfirmedaheterozygous pmol/L, FFA 1.06 mg/kg/min glucose).After pausing diazoxidefor whichconfirmedthediagnosisofRSTS. mg threetimesperday)andondemand pmol/L), suppressedketonesandlow h withnohypoglycaemiaattheendof g ( kg ( mmol/L, beta-hydroxybutyrate > − gk/i carbohydrates. 8 mg/kg/min 0.45 SDS),length47 mmol/L, undetectableinsulin < − 5 1.79 SDS),length90.4 < mg/kg/day) wasinitiated mlL, repeated 2.8 mmol/L), A Weltersandothers cm ( p.Glu mg three times per − 1.92 SDS).Cleft cm ( 349Lysfs*5 in mg/kg/day), − cm ( 3.7 SDS). mg/kg/ h and − 1.48 mg/ cm ( classified as likely pathogenic according to ACMG criteria (father) descent.Herbirthweightwas2400 consanguineous parentsofEnglish(mother)andBalkan ( The fourthindividual(P4)hasbeendescribedpreviously Case 4 syndrome. missense variantin syndromic conditionsidentifiedaheterozygous PTPN11 cardiofaciocutaneous syndromes( PGM1 approximately 5–6 glycaemic control.Fasting tolerance atthattimewas treatment wasinitiated(10.6 level of2.1 serum insulinconcentrations (39 hypoketotic hypoglycaemiawithinappropriatelyhigh further diagnosticevaluations.Recurrentepisodes of responsiveness following a delayed feed prompted yearsan episode of jitteriness and decreased At 1.4 as anepisodewitheyetwitchingsuggestiveofaseizure. feeding, parentsfirstnoticedexcessivesleepinessaswell yearwhenweaningheroffgastrostomy At around1.0 required the insertion of a percutaneous gastric tube. treatment. of theascendingaortawerediagnosed,notrequiring secundum atrialseptaldefectandanisolateddilatation to benon-functional.Atday8oflife,asmallostium diagnosed prenatallyandtherightkidneywaslaterfound of life.Rightmulticysticdysplastickidneyhadbeen intensive care treatment and nasal stenting at day 16 ( length 48 KCNQ1 HADH genes knowntocauseHH( feeding. the need for further continuous overnight gastrostomy > to 7.5 treatment wascommencedagainandgraduallyincreased suppressed ketones and FFA). Therefore, diazoxide than 6 formaltestingrevealedafastingtoleranceofless 7 days, hypoglycaemia Rubinstein–Taybi syndromeand 18 − 16 3.9 0.2 SDS).Bilateral choanal atresia required immediate ), confirmingthediagnosisofRubinstein–Taybi ). Shewasbornat36 weeks ofgestationtohealthy, non- t5 monthsof age, poor oral intake and GORD At 5 NGS excluded disease-causing pathogenic variants in mmol/L andafastingtoleranceof11–15 , , mg/kg/day, leading to stable blood glucose levels h (bloodglucose2.8 , , PMM1 HK1 KDM6A RAF1 cm ( mmol/L) ledtothediagnosis ofHH.Diazoxide , , − , HNF1A 0.15 SDS)andheadcircumference 33 PMM2 RIT1 , h withnohypoglycaemiaat theendof KMT2D EP300 , , , SOS1 Downloaded fromBioscientifica.com at09/24/202106:30:18PM SLC16A1 HNF4A (c.4505C , ABCC8 ). Genetic testing of other mmol/L, insulin26 MAFA mg/kg/day) andimproved https://eje.bioscientifica.com , pmol/L atbloodglucose , HRAS , , TRMT10A BRAF ALG3 181 > MPI T p.(Pro1502Leu)), , :2 , , INSR , g ( GCK NSD1 KRAS , − , h without 0.79 SDS), UCP2 , , KCNJ11 , pmol/L, GLUD1 de novo NRAS PAX6 125 ) or cm via freeaccess , , , ,

European Journal of Endocrinology https://eje.bioscientifica.com However, he developed post prandial HH(dumping which was associated with transient hyperinsulinism. harbours aheterozygous pathogenic variant in associated RSTS( are often more subtle compared to those with for about10%ofRSTSpatientsandtheclinicalfeatures is noteworthy, as heterozygous disease-relatedvariantin reported individualswithRSTSandHHharbour a clinical courseoffourRSTSpatientswithpersistentHH. here systematicallyreviewthemetabolicphenotypeand an increasedriskofseizuresandmentalretardation( with syndromicHH, as thesechildrenmayalready have damage ( treatment isessentialtopreventneuroglycopenicbrain syndrome, Kabukisyndromeandothers. but HHhasalsobeenreportedasafeatureinSotos of HHwithanumberthese.BWSisnotableexample conditions andanincreasedawarenessoftheassociation the diagnosisofmanyindividualswithsyndromic availability ofextendedgenetictestinghasalsofacilitated disease-associated genes( remains unknown,suggestingfurtherunrecognised clinically diagnosed patients with HH, geneticaetiology hyperinsulinism. However, in approximately 50% of identified tobeassociatedwithmonogeniccongenital HADH more thanninegenes( the identification of novel genes linked with HH. To date, Recent advancesinmoleculargenetictestinghaveenabled Discussion criteria ( ( missense variantin ( height is 100 at 4 years, and motordevelopmentisage-appropriate.Currently, from mild-to-moderateexpressivespeechdelay, cognitive dose increasesofdiazoxideasshehasgrown.Apart bolus gastrostomyfeedatbedtime.P4hasnotrequired managed withdiazoxidetreatment(6 features ofRSTSwereabsent.At4.0 years ofageHHisstill fissures andmicroretrognathia,whilesomeoftheclassic the fast.Facialfeatures included down-slanting palpebral 16 − Clinical Study 0.18 SDS). ), classifiedaslikelypathogenicaccordingtoACMG Three ofourfourpatientsandonetheformerly Early diagnosis of hypoglycaemiaandappropriate Genetic analysis revealed a heterozygous , 18 HNF1A 3 , ). 5 ). This holds particularly true for patients ). This holds particularly true for patients , 11 EP300 HNF4A ). Onlyoneofourfourpatients (P2) EP300 pathogenic variants only account cm ( , ABCC8 SLC16A1 (c4783T − 22 0.7 SDS) and weight 15.8 , , A Weltersandothers KCNJ11 23 , ). Thewidespread > UCP2 G p.(Phe1595Val)) mg/kg/day) anda EP300 , GCK ) have been ( , 15 CREBBP de novo CREBBP GLUD1 ). This 9 ). We kg - ,

not be assessed fully due to fluid overload. Subsequently not be assessedfullydue to fluid overload. Subsequently P2 there was an initial diazoxide response but this could showed good response to diazoxide (5–10 due tosirolimus-associatedsepsis.Incontrast,P3andP4 was ultimatelymanagedwithanintensivefeedingregime and nifedipine. This patient responded to sirolimus, but was variable. P1wasunresponsive to diazoxide, octreotide of life in P1 andP4. The responseto diazoxide treatment months in P2andP3,respectively, toapproximately18 reported featureinRSTS. have choanalatresiaorstenosis,whichisnotacommonly suggestive ofRSTS.Threeourpatientswerefoundto al et patient withtransientHHandRSTSreportedbyWyatt difficulties. Genetic testing was not available for the that wascarriedoutduetosevereGORDandfeeding hypoglycaemia wasNissenfundoplicationsurgery syndrome). Apossiblecauseofhispostprandial and survival. However,and survival. micelackingP300orCBPin normal pancreaticisletdevelopment, betacellfunction modification ( disturbance duetodefective genome-widehistone of RSTSthereforeappearsto beaglobaltranscriptional transcription factors( believed to participate in the activities of several different hold similarfunctionsinchromatinremodellingandare CREBBP with histoneacetyltransferaseactivity. The sequence identity. They act as transcriptional co-activators and highlyhomologousgenes,sharing elusive. underlying theassociationofHHwithRSTSremains linked inanyway. However, themolecularmechanism exceeds the expected frequency if both diagnoses were not patients eachsufferingfrombothconditionsclearly 000)( 000–50 (1:40 acarbose (P2). overnight gastrostomyfeeds(P1)orondemandand maintaineuglycaemicvia and7.9 years, P2, aged3.9 years (7.5 P3andP4stillrequiremoderatedosesof diazoxide 4 years yearsand gastrostomy feeding.Attheageofnow4.8 ( days of treatment could already be discontinued after 14 to moderatedosesofdiazoxide(10.9 effects. ThepatientreportedbyWyatt stopped after10 diazoxide wastrialledfordumpingsyndromebut hypoglycaemia Rubinstein–Taybi syndromeand 17 ). All of our patients additionally required continuous ). Allofourpatientsadditionallyrequiredcontinuous mg/kg/day and6 Age at diagnosis of HH varied from day 1 and 5 of age Age atdiagnosisofHHvariedfromday1and5age ie h aiyo ohRT 115 000)andHH Given therarityofbothRSTS(1:125 . ( 17 genesencodeP300andCBP, respectively, which EP300 ). P2andP3exhibitedtypicalclinical features 26 and mg/kg/day due to parental anxiety of its side mg/kg/day duetoparentalanxietyofitsside ). Both P300 and CBP are required for 15 mg/kg/day, respectively),whileP1and CREBBP , 25 Downloaded fromBioscientifica.com at09/24/202106:30:18PM 24 ). Themolecularmechanism ), thefindingofatleastfour areubiquitouslyexpressed 181 et al :2 > mg/kg/day) that mg/kg/day) that . was responsive . wasresponsive 60% ofprotein mg/kg/day). In mg/kg/day). In EP300 126 and via freeaccess

European Journal of Endocrinology equally tothisworkassharedfirst authors andsharedseniorauthors. A Welters, R El-Khairi, P Shah and S Kummer: These authors contributed Author contributionstatement the Wellcome. Research Network. This study makes use of DECIPHER, which is funded by National Institute for Health Research, through the Comprehensive Clinical of IrelandREC).Theresearchteamacknowledges the support of the the CambridgeSouthREC,andGEN/284/12 granted bytheRepublic Ethics Committeeapproval(10/H0305/83, has UKResearch granted by necessarily thoseofWellcometheDepartmentHealth.Thestudy The viewsexpressedin this publication are thoseoftheauthor(s)andnot of HealthandtheWellcomeSangerInstitute(grantnumberWT098051). parallel funding partnership between Wellcome andtheDepartment Health Innovation Challenge Fund (grant number HICF-1009-003), a The DDDstudy presents independent research commissionedby the Funding be could that interest of conflict perceived asprejudicingtheimpartialityofthisstudy. no is there that declare authors The Declaration ofinterest features suggestiveforRubinstein–Taybi syndrome. testing forpatientswithsyndromicHHandclinical recommend to include initiation ofappropriatetreatment.We furthermore symptoms, to ensure early recognition of HH and the particularly thosepresentingwithseizuresorunspecific to carefully screen RSTSpatients for hypoglycaemia, emphasize the need HH syndromes. Our observations novel association of RSTS and expands the spectrum of size. However, ourreportidentifiespersistentHHasa cannot bedrawnfromourdata,duetosmallsample respect toageatonsetofHHanddiazoxideresponsiveness CREBBP harbour apathogenicvariantin signalling in required toelucidatetheroleofbetacell-andalpha RSTS patients.Clearly, additionalmechanistic studies are progress tohypoinsulinismandglucoseintolerancein overt orsubclinicalhyperinsulinismtheroreticallymay Ep300 glucagon signalling remains elusive. Since intrinsic pathways or from other factors such as paracrine However, whetherhyperinsulinismresultsfrombetacell levels ofinsulinstronglysuggestingamechanisticlink. episodes wereassociatedwithinadequatelyelevated Inallourpatientshypoglycaemic to ourobservations. These findings in mice appear somehow contradictory become glucose intolerant due to hypoinsulinaemia ( pancreatic isletshavereducedalphaandbetacellmass Clinical Study In conclusion,althoughthreeofourfourpatients -knockout micebothdevelophypoinsulinaemia, , adefinitegenotype–phenotypecorrelationwith CREBBP - and EP300 EP300 and A Weltersandothers -associated HH. CREBBP EP300 inthe genetic ratherthan Crebbp - and 25 ). References the fourpatientsreportedhere. (Congenital Hyperinsulinism International) forconnecting us with one of We thankJulieRaskin cooperation andallowing us tosharetheircases. The authorswould like to thank all familymembersfortheirvaluable Acknowledgments

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