J Inherit Metab Dis (2015) 38:889–894 DOI 10.1007/s10545-014-9809-1 ORIGINAL ARTICLE First two unrelated cases of isolated sedoheptulokinase deficiency: A benign disorder? Mirjam M. C. Wamelink & RubenJ.J.F.Ramos& Annette P. M. van den Elzen & George J. G. Ruijter & Ramon Bonte & Luisa Diogo & Paula Garcia & Nelson Neves & Benjamin Nota & Arvand Haschemi & Isabel Tavares de Almeida & Gajja S. Salomons Received: 23 August 2014 /Revised: 29 December 2014 /Accepted: 30 December 2014 /Published online: 3 February 2015 # The Author(s) 2015. This article is published with open access at Springerlink.com Abstract We present the first two reported unrelated patients causal factor for the clinical phenotypes of our patients. This with an isolated sedoheptulokinase (SHPK) deficiency. The study illustrates the necessity of extensive functional and clin- first patient presented with neonatal cholestasis, hypoglyce- ical workup for interpreting a novel variant, including non- mia, and anemia, while the second patient presented with con- sense variants. genital arthrogryposis multiplex, multiple contractures, and dysmorphisms. Both patients had elevated excretion of erythritol and sedoheptulose, and each had a homozygous Introduction nonsense mutation in SHPK.SHPKisanenzymethatphos- phorylates sedoheptulose to sedoheptulose-7-phosphate, Sedoheptulokinase (SHPK; EC 2.7.1.14), formerly known as which is an important intermediate of the pentose phosphate carbohydrate-kinase-like (CARKL), is an enzyme that phos- pathway. It is questionable whether SHPK deficiency is a phorylates sedoheptulose to sedoheptulose-7-phosphate (sedoheptulose-7P) (Touchman et al 2000; Wamelink et al 2008; Kardon et al 2008; Haschemi et al 2012). SHPK is Communicated by: K. Michael Gibson highly expressed in liver, kidney, pancreas, and heart tissue. Electronic supplementary material The online version of this article Sedoheptulose-7P is an important intermediate of the pentose (doi:10.1007/s10545-014-9809-1) contains supplementary material, which is available to authorized users. phosphate pathway (PPP), a key pathway of carbohydrate metabolism. The PPP and glycolysis are tightly connected: * : : M. M. C. Wamelink ( ) B. Nota G. S. Salomons The PPP is located in the cytosol and is primarily responsible Department of Clinical Chemistry, Neuroscience Campus Amsterdam, VU University Medical Center, De Boelelaan 1117, for the production of cytosolic nicotinamide adenine dinucle- 1081HV Amsterdam, The Netherlands otide phosphate, reduced (NADPH) and ribose-5P. The SHPK e-mail: [email protected] protein co-localizes with glucose-6P dehydrogenase in the cytoplasm (Haschemi et al 2012). SHPK seems to be an im- R. J. J. F. Ramos : I. Tavares de Almeida Metabolism & Genetics, iMed.UL, Fac. Pharmacy- Univ. of Lisboa, portant regulatory enzyme, being responsible for feeding Lisboa, Portugal sedoheptulose-7P molecules to the PPP independently of glu- cose. Effectively, this allows the reversible function of A. P. M. van den Elzen transaldolase (TALDO) and/or transketolase when glyceralde- Department of Paediatrics, Reinier de Graaf Gasthuis Delft, Delft, The Netherlands hyde-3-phosphate, arising from the glycolytic pathway, is : used by the PPP, when increased amounts of NADPH and/or G. J. G. Ruijter R. Bonte ribose moieties are needed for nucleotide production Department of Clinical Genetics, Erasmus Medical Center, (Wamelink et al 2008; Nagy and Haschemi 2013). Free Rotterdam, The Netherlands sedoheptulose can be either derived dietarily from fruits and : : L. Diogo P. Garcia N. Neves vegetables (Kardon et al 2008) or formed enzymatically by Paediatric Hospital of Coimbra, Coimbra, Portugal dephosphorylation from sedoheptulose-7P or possibly from other heptoses, such as mannoheptulose or 7-O-galloyl- A. Haschemi Department of Laboratory Medicine, Medical University of Vienna, sedoheptulose. To date, no specific sedoheptulose-7P phos- Vienna, Austria phatase has been reported. 890 J Inherit Metab Dis (2015) 38:889–894 Knockdown of SHPK in a mouse macrophage cell line creatinine 132 μmol/L and urea 11 mmol/L at day 5 of life, resulted in increased glyceraldehyde-3P, xylulose-5P, and which normalized on day 10). He has chronic diarrhea, with ribose-5P intracellular levels. Sedoheptulose concentrations steatorrhea and severe growth retardation including short stat- were not notably changed, while sedoheptulose-7P was sig- ure and macrocephaly (relative to stature). Frequent, mostly nificantly decreased (Haschemi et al 2012), which resulted in asymptomatic, short-fasting hypoglycemic episodes (with rerouting of glucose from aerobic to anaerobic metabolism normal lactate and ketones) and postprandial hyperglycemia and was accompanied by a decreased nicotinamide adenine aggravated by the end of the first year of life persist in spite of dinucleotide (NAD)/NADH ratio. In the same cell line, the frequent meals. Transient hypocortisolism was identified, but opposite was found by overexpressed SHPK, although hypoglycemia did not respond to specific treatment. He is sedoheptulose-7P concentrations remained normal. In a currently under exocrine pancreatic yeast supplementation. screen for new regulators of macrophage activation, over- He has moderate intellectual disability and neurosensorial expression of SHPK was found to block lipopolysaccha- deafness. He needed several blood transfusions due to chronic ride (LPS)-induced tumor necrosis factor alpha (TNFα) microcytic hypochromic anemia, with normal ferritin, secretion by these cells (Haschemi et al 2012). In vitro leucocytes, and platelets. Because of childhood infections and in vivo, SHPK transcript is endogenously downregu- (bronchiolitis and middle ear infections with febrile lated in mice and humans during LPS-induced inflamma- rhinopharyngitis), inpatient admission was needed due to dif- tion. In vitro, knockdown of the gene by micro-RNA- ficulty in glycemic control; immune system deficiency was adapted short hairpin RNA (shRNA-mir) results in mild ruled out. His abdominal skin is strikingly thin, with upper activation of macrophages. This indicates that SHPK- collateral circulation and diastasis recti without liver or spleen dependent metabolic reprogramming is required for proper enlargement. M1- and M2-like macrophage polarization and is a rate- Brain magnetic resonance imaging (MRI) was normal in limiting requirement for appropriate glucose flux during the neonatal period. At the age of 3 years, MRI showed ven- macrophage polarization (Haschemi et al 2012). tricular enlargement, cerebral subcortical atrophy, hyperin- So far, SHPK deficiency has not been described in humans tense periventricular lesions, hypomyelinization, and a as an isolated defect and is only known as a combined defect, Chiari malformation type 1 (Fig. 1). with cystinosis caused by a 57-kb deletion extending from A broad etiological investigation including peroxisomal exon 10 of CTNS (cystinosin, lysosomal cystine transporter), function, carbohydrate-deficient transferrin, acylcarnitine pro- upstream through SHPK/CARKL,tointron2ofTRPV1 (tran- file, urinary organic acids, microarray comparative genomic sient receptor potential vanilloid 1) (Touchman et al 2000; hybridization (CGH) and UBR1, SBDS,andCOX412 genes Freed et al 2011). Patients with this deletion have the infantile has been inconclusive. At the age of 20 months, during a nephropathic cystinosis type (MIM 219800), but the clinical metabolic workup, elevated urinary concentrations were relevance of SHPK deficiency remains unclear. In urine of found for erythritol and sedoheptulose with gas chromatogra- these patients, high concentrations of sedoheptulose and phy mass spectrometry (GC-MS). His immune system was erythritol are detected, and in bloodspots, sedoheptulose is evaluated. Immunoglobulin (Ig) G, A, M, and E levels were also elevated compared with controls or patients with isolated normal; leucocyte number and distribution and lymphocyte cystinosis (Wamelink et al 2008, 2011). populations T, B, and NK were investigated; an inverted We diagnosed two unrelated patients with isolated SHPK CD4/CD8 and low CD19 and CD56 were found but were deficiency caused by different nonsense mutations in SHPK. not considered relevant. In the lymphoblast transformation test, there was a normal proliferative response to the mitogens phytohemagglutinin(PHA), pokeweed mitogen (PWM), and Materials and methods staphylococcal protein A (SPA). Patient 2, a girl (currently 2 years old), second child of Patients healthy consanguineous parents from Turkish heritage, was born at term. External cephalic version was successfully per- Patient 1, a boy (currently 3 years old), was born after formed antenatally because of breech presentation. She pre- 35 weeks’ gestation from a healthy Caucasian mother and sented at birth with perinatal asphyxia, birth weight of 2,580 g unknown father (suspected consanguineous relationship). (P2.3–P5), congenital arthrogryposis multiplex, hip dysplasia, The infant presented with perinatal asphyxia, birth weight of and numerous contractures. She has multiple dysmorphisms: 1,750 g (P2.3–P5), craniofacial dysmorphisms (high forehead round, asymmetrical eyes (right eye larger) with ptosis and with very large fontanels, hypotelorism, and small orbits), Bells phenomenon; small mouth; high nasal bridge; dysplastic unilateral inguinal hernia, and a sepsis-like condition with low-set ears, most prominent on the right; adducted thumbs; intestinal pseudoobstruction, transient hypoglycemia, chole- strikingly