Hyperinsulinism/hyperammonemia syndrome caused by biallelic SLC25A36 mutation.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome has been known to be caused by dominant gain-of-function mutations in GLUD1, encoding the mitochondrial enzyme glutamate dehydrogenase. Pathogenic GLUD1 mutations enhance enzymatic activity by reducing its sensitivity to allosteric inhibition by GTP. Two recent independent studies showed that a similar HI/HA phenotype can be caused by biallelic mutations in SLC25A36, encoding pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine and guanine nucleotides across the inner mitochondrial membrane: one study reported a single case caused by a homozygous truncating mutation in SLC25A36 resulting in lack of expression of SLC25A36 in patients' fibroblasts. A second study described two siblings with a splice site mutation in SLC25A36, causing reduction of mitochondrial GTP content, putatively leading to hyperactivation of glutamate dehydrogenase. In an independent study, through combined linkage analysis and exome sequencing, we demonstrate in four individuals of two Bedouin Israeli related families the same disease-causing SLC25A36 (NM_018155.3) c.284 + 3A > T homozygous splice-site mutation found in the two siblings. We demonstrate that the mutation, while causing skipping of exon 3, does not abrogate expression of mRNA and protein of the mutant SLC25A36 in patients' blood and fibroblasts. Affected individuals had hyperinsulinism, hyperammonemia, borderline low birth weight, tonic-clonic seizures commencing around 6 months of age, yet normal intellect and no significant other morbidities. Chronic constipation, hypothyroidism, and developmental delay previously described in a single patient were not found. We thus verify that biallelic SLC25A36 mutations indeed cause HI/HA syndrome and clearly delineate the disease phenotype.

Addition of galactose-1-phosphate measurement enhances newborn screening for classical galactosemia.

Galactosemia is an inborn disorder of carbohydrate metabolism of which early detection can prevent severe illness. Although the assay for galactose-1-phosphate uridyltransferase (GALT) enzyme activity has been available since the 1960s, many issues prevented it from becoming universal. In order to develop the Israeli newborn screening pilot algorithm for galactosemia, flow injection analysis tandem mass spectrometry measurement of galactose-1-phosphate in archived dried blood spots from newborns with classical galactosemia, galactosemia variants, epimerase deficiency, and normal controls, was conducted. Out of 431 330 newborns screened during the pilot study (30 months), two with classical galactosemia and four with epimerase deficiency were identified and confirmed. Five false positives and no false negatives were recorded. Following this pilot study, the Israeli final and routine newborn screening algorithm, as recommended by the Advisory Committee to the National Newborn Screening Program, now consists of galactose-1-phosphate measurement integrated into the routine tandem mass spectrometry panel as the first-tier screening test, and GALT enzyme activity as the second-tier performed to identify only newborns suspected to be at risk for classical galactosemia. The GALT enzyme activity cut-off used in the final algorithm was lowered in order to avoid false positives.

Whole-exome sequencing reveals a monogenic cause in 56% of individuals with laterality disorders and associated congenital heart defects.

BACKGROUND: The molecular basis of heterotaxy and congenital heart malformations associated with disruption of left-right asymmetry is broad and heterogenous, with over 25 genes implicated in its pathogenesis thus far. OBJECTIVE: We sought to elucidate the molecular basis of laterality disorders and associated congenital heart defects in a cohort of 30 unrelated probands of Arab-Muslim descent, using next-generation sequencing techniques. METHODS: Detailed clinical phenotyping followed by whole-exome sequencing (WES) was pursued for each of the probands and their parents (when available). Sanger sequencing was used for segregation analysis of disease-causing mutations in the families. RESULTS: Using WES, we reached a molecular diagnosis for 17 of the 30 probands (56.7%). Genes known to be associated with heterotaxy and/or primary ciliary dyskinesia, in which homozygous pathogenic or likely pathogenic variants were detected, included CFAP53 (CCDC11), CFAP298 (C21orf59), CFAP300, LRRC6, GDF1, DNAAF1, DNAH5, CCDC39, CCDC40, PKD1L1 and TTC25. Additionally, we detected a homozygous disease causing mutation in DAND5, as a novel recessive monogenic cause for heterotaxy in humans. Three additional probands were found to harbour variants of uncertain significance. These included variants in DNAH6, HYDIN, CELSR1 and CFAP46. CONCLUSIONS: Our findings contribute to the current knowledge regarding monogenic causes of heterotaxy and its associated congenital heart defects and underscore the role of next-generation sequencing techniques in the diagnostic workup of such patients, and especially among consanguineous families.

Deep intronic variant in the ARSB gene as the genetic cause for Maroteaux-Lamy syndrome (MPS VI).

Maroteaux-Lamy syndrome (MPS-VI) is a rare autosomal-recessive disorder with a wide spectrum of clinical manifestations, ranging from an attenuated to a rapidly progressive disease. It is caused by variants in ARSB, which encodes the lysosomal arylsulfatase B (ARSB) enzyme, part of the degradation process of glycosaminoglycans in lysosomes. Over 220 variants have been reported so far, with a majority of missense variants. We hereby report two siblings of Bedouin origin with a diagnosis of MPS-VI. Western blots in patient fibroblasts revealed total absence of ARSB protein production. Complete sequencing of the coding region of ARSB did not identify a candidate disease-associated variant. However, deep sequencing of the noncoding region of ARSB by whole genome sequencing (WGS) revealed a c.1142+581A to G variant. The variant is located within intron 5 and fully segregated with the disease in the family. Determination of the genetic cause for these patients enabled targeted treatment by enzyme replacement therapy, along with appropriate genetic counseling and prenatal diagnosis for the family. These results highlight the advantage of WGS as a powerful tool, for improving the diagnostic rate of rare disease-causing variants, and emphasize the importance of studying deep intronic sequence variation as a cause of monogenic disorders.

The role of orotic acid measurement in routine newborn screening for urea cycle disorders.

Urea cycle disorders (UCDs), including OTC deficiency (OTCD), are life-threatening diseases with a broad clinical spectrum. Early diagnosis and initiation of treatment based on a newborn screening (NBS) test for OTCD with high specificity and sensitivity may contribute to reduction of the significant complications and high mortality. The efficacy of incorporating orotic acid determination into routine NBS was evaluated. Combined measurement of orotic acid and citrulline in archived dried blood spots from newborns with urea cycle disorders and normal controls was used to develop an algorithm for routine NBS for OTCD in Israel. Clinical information and genetic confirmation results were obtained from the follow-up care providers. About 1147986 newborns underwent routine NBS including orotic acid determination, 25 of whom were ultimately diagnosed with a UCD. Of 11 newborns with OTCD, orotate was elevated in seven but normal in two males with early-onset and two males with late-onset disease. Orotate was also elevated in archived dried blood spots of all seven retrospectively tested historical OTCD patients, only three of whom had originally been identified by NBS with low citrulline and elevated glutamine. Among the other UCDs emerge, three CPS1D cases and additional three retrospective CPS1D cases otherwise reported as a very rare condition. Combined levels of orotic acid and citrulline in routine NBS can enhance the detection of UCD, especially increasing the screening sensitivity for OTCD and differentiate it from CPS1D. Our data and the negligible extra cost for orotic acid determination might contribute to the discussion on screening for proximal UCDs in routine NBS.

B4GALT1-congenital disorders of glycosylation: Expansion of the phenotypic and molecular spectrum and review of the literature.

A congenital disorder of glycosylation due to biallelic mutations in B4GALT1 has been previously reported in only three patients with two different mutations. Through homozygosity mapping followed by segregation analysis in an extended pedigree, we identified three additional patients homozygous for a novel mutation in B4GALT1, expanding the phenotypic spectrum of the disease. The patients showed a uniform clinical presentation with intellectual disability, marked pancytopenia requiring chronic management, and novel features including pulmonary hypertension and nephrotic syndrome. Notably, affected individuals exhibited a moderate elevation of Man3GlcNAc4Fuc1 on serum N-glycan analysis, yet two of the patients had a normal pattern of transferrin glycosylation in repeated analysis. The novel mutation is the third disease-causing variant described in B4GALT1, and the first one within its transmembrane domain.

Natural history of multiple sulfatase deficiency: Retrospective phenotyping and functional variant analysis to characterize an ultra-rare disease.

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder caused by pathogenic variants in SUMF1. This gene encodes formylglycine-generating enzyme (FGE), a protein required for sulfatase activation. The clinical course of MSD results from additive effect of each sulfatase deficiency, including metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IIIE, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. While it is known that affected individuals demonstrate a complex and severe phenotype, the genotype-phenotype relationship and detailed clinical course is unknown. We report on 35 cases enrolled in our retrospective natural history study, n = 32 with detailed histories. Neurologic function was longitudinally assessed with retrospective scales. Biochemical and computational modeling of novel SUMF1 variants was performed. Genotypes were classified based on predicted functional change, and each individual was assigned a genotype severity score. The median age at symptom onset was 0.25 years; median age at diagnosis was 2.7 years; and median age at death was 13 years. All individuals demonstrated developmental delay, and only a subset of individuals attained ambulation and verbal communication. All subjects experienced an accumulating systemic symptom burden. Earlier age at symptom onset and severe variant pathogenicity correlated with poor neurologic outcomes. Using retrospective deep phenotyping and detailed variant analysis, we defined the natural history of MSD. We found that attenuated cases can be distinguished from severe cases by age of onset, attainment of ambulation, and genotype. Results from this study can help inform prognosis and facilitate future study design.

TMEM70 deficiency: Novel mutation and hypercitrullinemia during metabolic decompensation.

Respiratory chain disorders comprise a heterogeneous group of diseases that are the result of mutations in nuclear or mitochondrial genes. TMEM70 encodes a nuclear protein involved in the assembly of respiratory chain complex V. Although mutations in various genes can result in isolated complex V deficiency; TMEM70 mutations represent the most common reported etiology. TMEM70 deficiency is known to cause a syndrome of neonatal mitochondrial encephalocardiomyopathy, accompanied by elevated lactate and hyperammonemia. Elevated citrulline has been reported previously in different inborn errors of metabolism, although uncommonly associated with TMEMT70 deficiency. We present a series of two siblings diagnosed with TMEM70 deficiency, and describe hypercitrullinemia during decompensation as a new finding in this condition. The cause of hyperammonemia in TMEM70 deficiency was previously assumed to be related to carbamoyl phosphate synthase 1 deficiency, but our finding of hypercitrullinemia rules out this possibility. We thus propose a different etiology for the hyperammonemia seen in these patients.

Novel homozygous ENPP1 mutation causes generalized arterial calcifications of infancy, thrombocytopenia, and cardiovascular and central nervous system syndrome.

Generalized arterial calcifications of infancy (GACI) is caused by mutations in ENPP1. Other ENPP1-related phenotypes include pseudoxanthoma elasticum, hypophosphatemic rickets, and Cole disease. We studied four children from two Bedouin consanguineous families who presented with severe clinical phenotype including thrombocytopenia, hypoglycemia, hepatic, and neurologic manifestations. Initial working diagnosis included congenital infection; however, patients remained without a definitive diagnosis despite extensive workup. Consequently, we investigated a potential genetic etiology. Whole exome sequencing (WES) was performed for affected children and their parents. Following the identification of a novel mutation in the ENPP1 gene, we characterized this novel multisystemic presentation and revised relevant imaging studies. Using WES, we identified a novel homozygous mutation (c.556G > C; p.Gly186Arg) in ENPP1 which affects a highly conserved protein domain (somatomedin B2). ENPP1-associated genetic diseases exhibit phenotypic heterogeneity depending on mutation type and location. Follow-up clinical characterization of these families allowed us to revise and detect new features of systemic calcifications, which established the diagnosis of GACI, expanding the phenotypic spectrum associated with ENPP1 mutations. Our findings demonstrate that this novel ENPP1 founder mutation can cause a fatal multisystemic phenotype, mimicking severe congenital infection. This also represents the first reported mutation affecting the SMB2 domain, associated with GACI.

A novel homozygous SLC25A1 mutation with impaired mitochondrial complex V: Possible phenotypic expansion.

SLC25A1 mutations are associated with combined D,L-2-hydroxyglutaric aciduria (DL- 2HGA; OMIM #615182), characterized by muscular hypotonia, severe neurodevelopmental dysfunction and intractable seizures. SLC25A1 encodes the mitochondrial citrate carrier (CIC), which mediates efflux of the mitochondrial tricarboxylic acid (TCA) cycle intermediates citrate and isocitrate in exchange for cytosolic malate. Only a single family with an SLC25A1 mutation has been described in which mitochondrial respiratory chain dysfunction was documented, specifically in complex IV. Five infants of two consanguineous Bedouin families of the same tribe presented with small head circumference and neonatal-onset encephalopathy with severe muscular weakness, intractable seizures, respiratory distress, and lack of psychomotor development culminating in early death. Ventricular septal defects (VSD) were demonstrated in three patients. Blood and CSF lactate were elevated with normal levels of plasma amino acids and free carnitine and increased 2-OH-glutaric acid urinary exertion. EEG was compatible with white matter disorder. Brain MRI revealed ventriculomegaly, thin corpus callosum with increased lactate peak on spectroscopy. Mitochondrial complex V deficiency was demonstrated in skeletal muscle biopsy of one infant. Homozygosity mapping and sequencing ruled out homozygosity of affected individuals in all known complex V-associated genes. Whole exome sequencing identified a novel homozygous SLC25A1 c.713A>G (p.Asn238Ser) mutation, segregating as expected in the affected kindred and not found in 220 control alleles. Thus, SLC25A1 mutations might be associated with mitochondrial complex V deficiency and should be considered in the differential diagnosis of mitochondrial respiratory chain defects.

Pulmonary involvement in Niemann-Pick C type 1.

Niemann-Pick disease type C (NPC) is a lysosomal storage disorder caused by mutations in either NPC-1 or NPC-2 genes, resulting in abnormal intracellular cholesterol trafficking. The estimated prevalence of NPC disease is 1: 120,000-150,000. Lung involvement has been described in only few patients with NPC, mostly NPC2. We describe a series of 12 patients, originating from six families all homozygotes to the p.R404Q (c.1211G > A) mutation of NPC1 gene; nine of them had significant pulmonary manifestations. All patients were followed in our medical center. Nine of the patients had pulmonary involvement, with recurrent pneumonia as the first manifestation in most, followed by recurrent wheezing episodes and subsequent development of interstitial lung disease with chronic need for oxygen support. Seven patients were reported of having interstitial disease by various imaging modalities.Conclusion: Pulmonary involvement in NPC1 is more common than previously reported. It is characterized as primary obstructive and restrictive lung disease and not only as part of neurologic sequel of NPC. It can lead to respiratory insufficiency and death from respiratory failure. What is Known: • Lung involvement has been described in only few patients with NPC. • Most reported NPC cases with pulmonary involvement were of NPC2. What is New: • Pulmonary involvement in NPC1 is more common than previously reported. • Pulmonary involvement in NPC1 should be considered as part of the disease and be thoroughly assessed and managed.

Exome sequencing in Jewish and Arab patients with rhabdomyolysis reveals single-gene etiology in 43% of cases.

BACKGROUND: Rhabdomyolysis is a clinical emergency that may cause acute kidney injury (AKI). It can be acquired or due to monogenic mutations. Around 60 different rare monogenic forms of rhabdomyolysis have been reported to date. In the clinical setting, identifying the underlying molecular diagnosis is challenging due to nonspecific presentation, the high number of causative genes, and current lack of data on the prevalence of monogenic forms. METHODS: We employed whole exome sequencing (WES) to reveal the percentage of rhabdomyolysis cases explained by single-gene (monogenic) mutations in one of 58 candidate genes. We investigated a cohort of 21 unrelated families with rhabdomyolysis, in whom no underlying etiology had been previously established. RESULTS: Using WES, we identified causative mutations in candidate genes in nine of the 21 families (43%). We detected disease-causing mutations in eight of 58 candidate genes, grouped into the following categories: (1) disorders of fatty acid metabolism (CPT2), (2) disorders of glycogen metabolism (PFKM and PGAM2), (3) disorders of abnormal skeletal muscle relaxation and contraction (CACNA1S, MYH3, RYR1 and SCN4A), and (4) disorders of purine metabolism (AHCY). CONCLUSIONS: Our findings demonstrate a very high detection rate for monogenic etiologies using WES and reveal broad genetic heterogeneity for rhabdomyolysis. These results highlight the importance of molecular genetic diagnostics for establishing an etiologic diagnosis. Because these patients are at risk for recurrent episodes of rhabdomyolysis and subsequent risk for AKI, WES allows adequate prophylaxis and treatment for these patients and their family members and enables a personalized medicine approach.

Primary and maternal 3-methylcrotonyl-CoA carboxylase deficiency: insights from the Israel newborn screening program.

BACKGROUND: 3-Methylcrotonyl-CoA carboxylase deficiency (3MCCD) is an inborn error of leucine catabolism. Tandem mass spectrometry newborn screening (NBS) programs worldwide confirmed 3MCCD to be the most common organic aciduria and a relatively benign disorder with favorable outcome. In addition, several asymptomatic 3MCCD mothers were initially identified following abnormal screening of their healthy babies and were appropriately termed maternal 3MCCD. METHODS: This is a retrospective study that summarizes all the clinical, biochemical, and genetic data collected by questionnaires of all 3MCCD individuals that were identified by the extended Israeli NBS program since its introduction in 2009 including maternal 3MCCD cases. RESULTS: A total of 36 3MCCD subjects were diagnosed within the 50-month study period; 16 were classified primary and 20 maternal cases. Four additional 3MCCD individuals were identified following sibling screening. All maternal 3MCCD cases were asymptomatic except for one mother who manifested childhood hypotonia. Most of the primary 3MCCD individuals were asymptomatic except for two whose condition was also complicated by severe prematurity. Initial dried blood spot (DBS) free carnitine was significantly lower in neonates born to 3MCCD mothers compared with newborns with primary 3MCCD (p = 0.0009). Most of the mutations identified in the MCCC1 and MCCC2 genes were missense, five of them were novel. CONCLUSIONS: Maternal 3MCCD is more common than previously thought and its presence may be initially indicated by low DBS free carnitine levels. Our findings provide additional confirmation of the benign nature of 3MCCD and we suggest to exclude this disorder from NBS programs.

Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein TIMM50.

TIMM50, an essential TIM23 complex subunit, is suggested to facilitate the import of ∼60% of the mitochondrial proteome. In this study, we characterized a TIMM50 disease causing mutation in human fibroblasts, and noted significant decreases in TIM23 core protein levels (TIMM50, TIMM17A/B, and TIMM23). Strikingly, TIMM50 deficiency had no impact on the steady state levels of most of its substrates, challenging the currently accepted import dogma of the essential general import role of TIM23 and suggesting that fully functioning TIM23 complex is not essential for maintaining the steady state level of the majority of mitochondrial proteins. As TIMM50 mutations have been linked to severe neurological phenotypes, we aimed to characterize TIMM50 defects in manipulated mammalian neurons. TIMM50 knockdown in mouse neurons had a minor effect on the steady state level of most of the mitochondrial proteome, supporting the results observed in patient fibroblasts. Amongst the few affected TIM23 substrates, a decrease in the steady state level of components of the intricate oxidative phosphorylation and mitochondrial ribosome complexes was evident. This led to declined respiration rates in fibroblasts and neurons, reduced cellular ATP levels and defective mitochondrial trafficking in neuronal processes, possibly contributing to the developmental defects observed in patients with TIMM50 disease. Finally, increased electrical activity was observed in TIMM50 deficient mice neuronal cells, which correlated with reduced levels of KCNJ10 and KCNA2 plasma membrane potassium channels, likely underlying the patients' epileptic phenotype.

A deletion mutation in TMEM38B associated with autosomal recessive osteogenesis imperfecta.

Autosomal recessive osteogenesis imperfecta (OI) was diagnosed in three unrelated Israeli Bedouin consanguineous families. Fractures were evident in all cases in infancy. Genome-wide linkage analysis ruled out association with any of the known OI genes, and identified a single homozygosity locus of approximately 2 Mb on chromosome 9 common to all affected individuals (maximum multipoint lod score 6.5). Whole exome sequencing identified only a single mutation within this locus that was shared by all affected individuals: a homozygous deletion mutation of exon 4 of TMEM38B, leading to an early stop codon and a truncated protein, as well as low TMEM38B mRNA levels. TMEM38B encodes TRIC-B, a ubiquitous component of TRIC, a monovalent cation-specific channel involved in Ca(2+) release from intracellular stores that has been shown to act in cell differentiation. Molecular mechanisms through which a TMEM38B mutation might lead to an OI phenotype are yet to be explored.

Long-term administration of intravenous Trappsol® Cyclo™ (HP-ß-CD) results in clinical benefits and stabilization or slowing of disease progression in patients with Niemann-Pick disease type C1: Results of an international 48-week Phase I/II trial.

Background: Niemann-Pick disease type C (NPC) is a rare, fatal, pan-ethnic, autosomal recessive lysosomal storage disease characterized by progressive major organ failure and neurodegeneration. Preclinical studies confirmed a critical role of systemically administered hydroxypropyl-ß-cyclodextrin (HP-ß-CD; Trappsol® Cyclo™) in cholesterol metabolism and homeostasis in peripheral tissues of the body, including the liver, and in the central nervous system (CNS). Herein, the pharmacokinetics (PK), safety, and efficacy of HP-ß-CD, and biomarkers of NPC were assessed in pediatric and adult patients with NPC1. Methods: This was a multicenter, Phase I/II, randomized, double-blind, parallel-group, 48-week study (ClinicalTrials.gov identifier NCT02912793) to compare the PK of three different single intravenous (IV) doses of HP-ß-CD in pediatric and adult patients with NPC1 and to evaluate the efficacy and tolerability of three different dosages of HP-ß-CD in patients with NPC1 after long-term treatment. Twelve patients aged at least 2 years (2-39 years of age) with a confirmed diagnosis of NPC1 were randomized to receive one of three IV doses of HP-ß-CD (1500 mg/kg, 2000 mg/kg, or 2500 mg/kg) every 2 weeks for 48 weeks. All patients received HP-ß-CD; there was no placebo or other control. PK testing of plasma and cerebrospinal fluid (CSF) was at set times after the first infusion. Pharmacodynamic assessments included biomarkers of cholesterol metabolism (synthesis and breakdown products), N-palmitoyl-O-phosphocholineserine (PPCS), and specific biomarkers of CSF neurodegeneration (including total Tau), CNS inflammation (glial fibrillary acidic protein [GFAP] and tumor necrosis factor α [TNFα]), CNS cholesterol metabolism (24S-hydroxycholesterol) and inflammatory markers. Efficacy measures included clinical disease severity, neurologic symptoms, and clinical impressions of improvement. Safety assessment included physical examination, vital signs, clinical safety laboratory assessment and adverse events (AEs). Results: Nine patients completed the study, 2 in the 1500 mg/kg group, 4 in the 2000 mg/kg group and 3 in the 2500 mg/kg group. Three patients (all in the 1500 mg/kg group) discontinued the study because of either physician decision/site Principal Investigator (PI) discretion, withdrawal by subject/patient/parent/guardian, or other non-safety reasons. In 5 patients who underwent serial lumbar punctures, HP-ß-CD was detected in the CSF. Of the 9 patients who completed the study, 8 (88.9%) improved in at least two domains of the 17-Domain Niemann-Pick disease Type C-Clinical Severity Scale (17D-NPC-CSS), and 6 of these patients improved in at least one domain viewed by patients and their caregivers to be key to quality of life, namely, speech, swallow, fine and gross motor skills, and cognition. Of the 9 patients who completed the study, 7 were viewed by their treating physicians as having improved to some degree at the end of the study, and 2 remained stable; both outcomes are highly relevant in a progressive neurodegenerative disease. Some patients and families reported improvement in quality of life.All three doses of HP-ß-CD were well tolerated overall, with most treatment-emergent adverse events transient, mild-to-moderate in nature, and considered by the site PIs to be not related to study drug. Interpretation: This 48-week trial is the longest to date to evaluate the safety, tolerability, and efficacy across multiple clinical endpoints of IV administration of Trappsol® Cyclo™ (HP-ß-CD) in NPC1 patients. In pediatric and adult patients with NPC, Trappsol® Cyclo™ IV improved clinical signs and symptoms and was generally well tolerated. The findings presented here demonstrate a favorable benefit-risk profile and support the global pivotal trial now underway to evaluate the long-term treatment benefits and the potential of Trappsol® Cyclo™ as a disease-modifying treatment in this patient population.

Hereditary orotic aciduria identified by newborn screening.

Introduction: Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria. Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill. Methods: Measuring orotic acid as part of expanded newborn screening using flow injection analysis tandem mass spectrometry. Results: Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened. The screen has identified ten Muslim Arab newborns that remain asymptomatic so far, with DBS orotic acid elevated up to 10 times the upper reference limit. Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the UMPS gene. Conclusion: Newborn screening measuring of orotic acid, now integrated into the routine tandem mass spectrometry panel, is capable of identifying neonates with hereditary orotic aciduria.

Elevated Alpha-Fetoprotein in Infantile-Onset Niemann-Pick Type C Disease with Liver Involvement.

Niemann-Pick disease type C (NPC) is a rare autosomal recessive neuro-visceral lipid storage disease. We describe nine cases of infantile-onset NPC with various genetic mutations in the NPC1 gene, which presented with neonatal cholestasis. Serum alpha-fetoprotein (AFP) levels were obtained as part of their workup during the first four months of life. In eight of nine (89%) patients, serum AFP demonstrated elevated levels. Seven infants displayed marked elevations, ranging from 4 to 300 times the upper limit for age-adjusted norms. In most patients, AFP levels peaked during the initial test and declined over time as cholestasis resolved. We conclude that elevated AFP levels are a common, although non-specific, marker for NPC-associated liver disease. These findings demonstrate the benefit of including AFP levels in the workup of neonatal liver disease, especially if there is accompanied cholestasis and if NPC is suspected.

What Can We Learn from the Parents of Children Affected with Mucopolysaccharidosis Type III-A in Israel?

Sanfilippo Syndrome, or mucopolysaccharidosis type III (MPS III), is a group of autosomal-recessive lysosomal storage disorders leading to tissue accumulation of heparan sulfate. MPS III is caused by deficiency in one of 4 enzymes involved in lysosomal degradation of heparan sulfate. Based on the relevant enzyme deficiency, 4 types have been recognized. MPS III constitutes a progressive neurodegenerative and systemic disorder. Parents of children diagnosed with MPS III were interviewed using a retrospective questionnaire based on the known clinical manifestations of MPS III. Eight patients from 4 unrelated families of varied ethnic origin were included. All children were diagnosed with MPS type III-A. Average age at diagnosis was 6.1 years. The most common early clinical manifestations leading to parental suspicion of illness were speech delay and coarse facial features. All children were reported to have global developmental delay, sleep disorders, recurrent infections, hyperactivity, and decreased hearing. The time from first medical inquiry until diagnosis was over 2 years on average, consistent with the delay in diagnosis described in the literature. MPS III children frequently undergo early and repeated ear, nose and throat surgeries, thus we suggest that a high index of suspicion is warranted in relevant clinical circumstances.