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Background X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder associated with leukodystrophy, myeloneuropathy and adrenocortical insufficiency. We performed a retrospective cohort study to evaluate long-term outcome of patients with X-ALD. Method All patients with X-ALD diagnosed between 1989 and 2012 were included. Electronic patient charts were reviewed for clinical features, biochemical investigations, molecular genetic testing, neuroimaging, long-term outcome and treatment. Results Forty-eight patients from 18 unrelated families were included (15 females; 33 males). Seventeen patients were symptomatic at the time of the biochemical diagnosis including 14 with neurocognitive dysfunction and 3 with Addison disease only. Thirty-one asymptomatic individuals were identified by positive family history of X-ALD. During follow-up, eight individuals developed childhood cerebral X-ALD (CCALD), one individual developed adrenomyeloneuropathy (AMN), six individuals developed Addison disease only, and five individuals remained asymptomatic. Direct sequencing of ABCD1 confirmed the genetic diagnosis in 29 individuals. Seven patients with CCALD underwent hematopoietic stem cell transplantation (HSCT). Nine patients lost the follow-up. There was no correlation between clinical severity score, Loes score and elevated degree of elevated very long chain fatty acid (VLCFA) levels in CCALD. Conclusion Our study reports forty-eight new patients with X-ALD and their long-term outcome. Only 35% of the patients presented with neurological features or Addison disease. The remaining individuals were identified due to positive family history. Close monitoring of asymptomatic males resulted in early HSCT to prevent progressive lethal neurodegenerative disease. Identification of patients with X-ALD is important to improve neurodevelopmental outcome of asymptomatic males.

KCNQ2 has been reported as a frequent cause of autosomal dominant benign familial neonatal seizures. De novo likely pathogenic variants in KCNQ2 have been described in neonatal or early infantile onset epileptic encephalopathy patients. Here, we report a three-generation family with six affected patients with a novel likely pathogenic variant (c.628C>T; p.Arg210Cys) in KCNQ2. Four family members, three adults and a child, presented with a childhood seizure onset with variability in the severity of seizures and response to treatment, intellectual disability (ID) as well as behavioral problems. The two youngest affected patients had a variable degree of global developmental delay with no seizures at their current age. This three-generation family with six affected members expands the phenotypic spectrum of KCNQ2 associated encephalopathy to KCNQ2 associated ID and or childhood onset epileptic encephalopathy. We think that KCNQ2 associated epileptic encephalopathy should be included in the differential diagnosis of childhood onset epilepsy and early onset global developmental delay, cognitive dysfunction, or ID. Furthermore, whole exome sequencing in families with ID and history of autosomal dominant inheritance pattern with or without seizures, may further broaden the phenotypic spectrum of KCNQ2 associated epileptic encephalopathy or encephalopathy.

BCAP31, encoded by BCAP31, is involved in the export of transmembrane proteins from the endoplasmic reticulum. Pathogenic variants in BCAP31 results in global developmental delay, dystonia, deafness and dysmorphic features in males, called deafness, dystonia, and cerebral hypomyelination (DDCH) syndrome. We report a new patient with BCAP3-associated encephalopathy, DDCH syndrome, sensorineural hearing loss, generalized dystonia, and choreoathetosis. This 3.5-year-old boy had microcephaly and failure to thrive within the first 3 months of life. His brain MRI showed bilateral increased signal intensity in globus pallidus at age 3 months raising the suspicion of mitochondrial encephalopathy. His muscle biopsy revealed pleomorphic subsarcolemmal mitochondria collection in electron microscopy. Respiratory chain enzyme activities were normal in muscle. He was enrolled to a whole exome sequencing research study, which identified a hemizygous likely pathogenic truncating variant (c.533_536dup; p.Ser180AlafsX6) in BCAP31, inherited from his mother, who had sensorineural hearing loss and normal cognitive functions. We report a new patient with BCAP31-associated encephalopathy, DDCH syndrome, mimicking mitochondrial encephalopathy. We also report a heterozygous mother who has bilateral sensorineural hearing loss. This patient's clinical features, muscle histopathology, brain MRI features, and family history were suggestive of mitochondrial encephalopathy. Whole exome sequencing research study confirmed the diagnosis of BCAP31-associated encephalopathy, DDCH syndrome.

Background Congenital disorders of glycosylation (CDG) are inborn defects of glycan metabolism. They are multisystem disorders. Analysis of transferrin isoforms is applied as a screening test for CDG type I (CDG-I) and type II (CDG-II). We performed a retrospective cohort study to determine spectrum of phenotype and genotype and prevalence of the different subtypes of CDG-I and CDG-II. Material and methods All patients with CDG-I and CDG-II evaluated in our institution's Metabolic Genetics Clinics were included. Electronic and paper patient charts were reviewed. We set-up a high performance liquid chromatography transferrin isoelectric focusing (TIEF) method to measure transferrin isoforms in our Institution. We reviewed the literature for the rare CDG-I and CDG-II subtypes seen in our Institution. Results Fifteen patients were included: 9 with PMM2 -CDG and 6 with non- PMM2 -CDG (one ALG3 -CDG, one ALG9 -CDG, two ALG11 -CDG, one MPDU1 -CDG and one ATP6V0A2 -CDG). All patients with PMM2 -CDG and 5 patients with non- PMM2 -CDG showed abnormal TIEF suggestive of CDG-I or CDG-II pattern. In all patients, molecular diagnosis was confirmed either by single gene testing, targeted next generation sequencing for CDG genes, or by whole exome sequencing. Conclusion We report 15 new patients with CDG-I and CDG-II. Whole exome sequencing will likely identify more patients with normal TIEF and expand the phenotypic spectrum of CDG-I and CDG-II.

Background The dilated cardiomyopathy with ataxia syndrome is a rare autosomal recessive multisystem disorder caused by mutations in DNAJC19 . We present a new patient with a novel pathogenic variant in DNAJC19 with novel neuroimaging finding of progressive cerebellar atrophy. Patient Description and Results We describe a new patient with dilated cardiomyopathy with ataxia syndrome presenting with global developmental delay, hypotonia, ataxia, and dilated cardiomyopathy. During follow-up, her cardiac phenotype improved but she exhibited progressive cerebellar atrophy and developed bilateral increased T2 signal intensities in the thalami, parietal lobes, and pons on magnetic resonance imaging. Dilated cardiomyopathy and 3-methylglutaconic aciduria in her urine organic acid analysis also improved. Conclusions This child with dilated cardiomyopathy with ataxia syndrome developed progressive cerebellar atrophy, a novel feature of this syndrome. In individuals with global developmental delay, hypotonia, ataxia, the dilated cardiomyopathy with ataxia syndrome should be considered even in the differential diagnosis in the absence of cardiomyopathy or 3-methylglutaconic aciduria.

Arginine-glycine amidinotransferase (GATM) deficiency is an autosomal-recessive disorder caused by pathogenic variants in GATM. Clinical features include intellectual disability, hypotonia, and myopathy. Due to normal neurodevelopment in asymptomatic individuals on creatine monotherapy, GATM deficiency is a good candidate for newborn screening. To determine the carrier frequency of GATM deficiency, we performed functional characterization of rare missense variants in GATM reported as heterozygous in the Exome Variant Server database. To assess phenotype and genotype correlation, we developed a clinical severity scoring system. Two patients with mild phenotype had a nonsense missense variant. Severe phenotype was present in patients with missense as well as truncating variants. There seems to be no phenotype and genotype correlation. We cloned a novel GATM transcript. We found seven missense variants retaining 0% of wild-type GATM activity indicating putative pathogenicity. Based on our study results, high Genomic Evolutionary Rate Profiling conservation score, conserved amino acid substitution in species, and low allele frequency in exome databases would be the most sensitive in silico analysis tools to predict pathogenicity of missense variants. We present first study of the functional characterization of missense variants in GATM as well as clinical severity score of patients with GATM deficiency.

We report a new patient with refractory epilepsy associated with a novel pathogenic homozygous MED23 variant. This 7.5-year-old boy from consanguineous parents had infantile onset global developmental delay and refractory epilepsy. He was treated with the ketogenic diet at 2.5 years of age and became seizure free on the first day. He had microcephaly and truncal hypotonia. His brain MRI showed delayed myelination and thin corpus callosum. He was enrolled in a whole exome sequencing research study, which identified a novel, homozygous, likely pathogenic (c.1937A>G; p.Gln646Arg) variant in MED23. MED23 is a regulator of energy homeostasis and glucose production. Liver-specific Med23-knockout mice showed reduced liver gluconeogenesis and lower blood glucose levels compared to control mice. This is the first patient with documented refractory epilepsy caused by a novel homozygous pathogenic variant in MED23 expanding the phenotypic spectrum. Identification of the underlying genetic defect in MED23 sheds light on the possible mechanism of complete response to the ketogenic diet in this child. © 2016 Wiley Periodicals, Inc.

The system of assigning locus symbols to specify chromosomal regions that are associated with a familial disorder has a number of problems when used as a reference list of genetically determined disorders,including (I) erroneously assigned loci, (II) duplicated loci, (III) missing symbols or loci, (IV) unconfirmed loci and genes, (V) a combination of causative genes and risk factor genes in the same list, and (VI) discordance between phenotype and list assignment. In this article, we report on the recommendations of the International Parkinson and Movement Disorder Society Task Force for Nomenclature of Genetic Movement Disorders and present a system for naming genetically determined movement disorders that addresses these problems. We demonstrate how the system would be applied to currently known genetically determined parkinsonism, dystonia, dominantly inherited ataxia, spastic paraparesis, chorea, paroxysmal movement disorders, neurodegeneration with brain iron accumulation, and primary familial brain calcifications. This system provides a resource for clinicians and researchers that, unlike the previous system, can be considered an accurate and criterion-based list of confirmed genetically determined movement disorders at the time it was last updated.

Background GAMT deficiency is an autosomal recessive disorder of creatine biosynthesis causing developmental delays or intellectual disability in untreated patients as a result of irreversible brain damage occurring prior to diagnosis. Normal neurodevelopmental outcome has been reported in patients treated from neonatal period highlighting the importance of early treatment. Methods Five hundred anonymized newborns from the National Newborn Screening Program of The Netherlands were included into this pilot study. Direct sequencing of the coding region of the GAMT gene was applied following DNA extraction. The disease causing nature of novel missense variants in the GAMT gene was studied by overexpression studies. GAA and creatine was measured in blood dot spots. Results We detected two carriers, one with a known common (c.327G>A) and one with a novel mutation (c.297_309dup (p.Arg105Glyfs*) in the GAMT gene. The estimated incidence of GAMT deficiency was 1:250,000. We also detected five novel missense variants. Overexpression of these variants in GAMT deficient fibroblasts did restore GAMT activity and thus all were considered rare, but not disease causing variants including the c.131G>T (p.Arg44Leu) variant. Interestingly, this variant was predicted to be pathogenic by in silico analysis. The variants were included in the Leiden Open Variation Database (LOVD) database (www.LOVD.nl/GAMT). The average GAA level was 1.14 μmol/L ± 0.45 standard deviations. The average creatine level was 408 μmol/L ± 106. The average GAA/creatine ratio was 2.94 ± 0.136. Conclusion The estimated incidence of GAMT deficiency is 1:250,000 newborns based on our pilot study. The newborn screening for GAMT deficiency should be implemented to identify patients at the asymptomatic stage to achieve normal neurodevelopmental outcome for this treatable neurometabolic disease. Biochemical investigations including GAA, creatine and GAMT enzyme activity measurements are essential to confirm the diagnosis of GAMT deficiency. According to availability, all missense variants can be assessed functionally, as in silico prediction analysis of missense variants is not sufficient to confirm the pathogenicity of missense variants.

Pyridoxine dependent epilepsy (PDE) is an autosomal recessively inherited disorder. It is caused by mutations in the ALDH7A1 gene (PDE-ALDH7A1) encoding the alpha-aminoadipic semialdehyde dehydrogenase enzyme in the lysine catabolic pathway. The alpha-aminoadipic semialdehyde dehydrogenase enzyme deficiency leads to accumulation of alpha-aminoadipic semialdehyde and piperidine 6-carboxylic acid, the latter inactivates pyridoxal-5-phosphate. The majority of the patients present with neonatal onset intractable seizures with a dramatic response to pyridoxine therapy. Later seizure onset up to 3 yr of age has been reported too. Generalized tonic-clonic seizures are the most common seizure type. The treatment of PDE consists of high dose pyridoxine supplementation therapy. Since the underlying genetic defect was identified in the lysine catabolic pathway, few patients were treated with lysine-restricted diet to decrease, likely neurotoxic, alpha-aminoadipic semialdehyde and piperidine 6-carboxylic acid accumulation in the central nervous system.

SummaryObjective Epilepsy is a common neurologic disorder of childhood. To determine the genetic diagnostic yield in epileptic encephalopathy, we performed a retrospective cohort study in a single epilepsy genetics clinic. Methods We included all patients with intractable epilepsy, global developmental delay, and cognitive dysfunction seen between January 2012 and June 2014 in the Epilepsy Genetics Clinic. Electronic patient charts were reviewed for clinical features, neuroimaging, biochemical investigations, and molecular genetic investigations including targeted next-generation sequencing of epileptic encephalopathy genes. Results Genetic causes were identified in 28% of the 110 patients: 7% had inherited metabolic disorders including pyridoxine dependent epilepsy caused by ALDH7A1 mutation, Menkes disease, pyridox(am)ine-5-phosphate oxidase deficiency, cobalamin G deficiency, methylenetetrahydrofolate reductase deficiency, glucose transporter 1 deficiency, glycine encephalopathy, and pyruvate dehydrogenase complex deficiency; 21% had other genetic causes including genetic syndromes, pathogenic copy number variants on array comparative genomic hybridization, and epileptic encephalopathy related to mutations in the SCN1A, SCN2A, SCN8A, KCNQ2, STXBP1, PCDH19, and SLC9A6 genes. Forty-five percent of patients obtained a genetic diagnosis by targeted next-generation sequencing epileptic encephalopathy panels. It is notable that 4.5% of patients had a treatable inherited metabolic disease. Significance To the best of our knowledge, this is the first study to combine inherited metabolic disorders and other genetic causes of epileptic encephalopathy. Targeted next-generation sequencing panels increased the genetic diagnostic yield from 25% in patients with epileptic encephalopathy.

Creatine transporter deficiency (CRTR-D) is an X-linked inherited disorder of creatine transport. All males and about 50% of females have intellectual disability or cognitive dysfunction. Creatine deficiency on brain proton magnetic resonance spectroscopy and elevated urinary creatine to creatinine ratio are important biomarkers. Mutations in the SLC6A8 gene occur de novo in 30% of males. Despite reports of high prevalence of CRTR-D in males with intellectual disability, there are no true prevalence studies in the general population. To determine carrier frequency of CRTR-D in the general population we studied the variants in the SLC6A8 gene reported in the Exome Variant Server database and performed functional characterization of missense variants. We also analyzed synonymous and intronic variants for their predicted pathogenicity using in silico analysis tools. Nine missense variants were functionally analyzed using transient transfection by site-directed mutagenesis with In-Fusion HD Cloning in HeLa cells. Creatine uptake was measured by liquid chromatography tandem mass spectrometry for creatine measurement. The c.1654G>T (p.Val552Leu) variant showed low residual creatine uptake activity of 35% of wild type transfected HeLa cells and was classified as pathogenic. Three variants (c.808G>A; p.Val270Met, c.942C>G; p.Phe314Leu and c.952G>A; p.Ala318Thr) were predicted to be pathogenic based on in silico analysis, but proved to be non-pathogenic by our functional analysis. The estimated carrier frequency of CRTR-D was 0.024% in females in the general population. We recommend functional studies for all novel missense variants by transient transfection followed by creatine uptake measurement by liquid chromatography tandem mass spectrometry as fast and cost effective method for the functional analysis of missense variants in the SLC6A8 gene.

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Item does not contain fulltext Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.

Objectives Glycogen storage disease (GSD) types VI and IX are caused by phosphorylase system deficiencies. To evaluate the natural history and long-term treatment outcome of the patients with GSD-VI and -IX, we performed an observational retrospective case study of 21 patients with confirmed diagnosis of GSD-VI or -IX. Methods All patients with GSD-VI or -IX, diagnosed at The Hospital for Sick Children, were included. Electronic and paper charts were reviewed for clinical features, biochemical investigations, molecular genetic testing, diagnostic imaging, long-term outcome and treatment by two independent research team members. All information was entered into an Excel database. Results We report on the natural history and treatment outcomes of the 21 patients with GSD-VI and -IX and 16 novel pathogenic mutations in the PHKA2, PHKB, PHKG2 and PYGL genes. We report for the first time likely liver adenoma on liver ultrasound and liver fibrosis on liver biopsy specimens in patients with GSD-VI and mild cardiomyopathy on echocardiography in patients with GSD-VI and -IXb. Conclusion We recommend close monitoring in all patients with GSD-VI and -IX for the long-term liver and cardiac complications. There is a need for future studies if uncooked cornstarch and high protein diet would be able to prevent long-term complications of GSD-VI and -IX.

Pyridox(am)ine-5-phosphate oxidase deficiency is an autosomal recessive disorder of pyridoxine metabolism. Intractable neonatal epileptic encephalopathy is the classical presentation. Pyridoxal-5-phosphate or pyridoxine supplementation improves symptoms. We report a patient with myoclonic and tonic seizures at the age of 1 hour. Pyridoxal-5-phosphate was started on the first day of life and seizures stopped at the age of 3 days, but encephalopathy persisted for 4 weeks. She had normal neurodevelopmental outcome at the age of 12 months on pyridoxal-5-phosphate monotherapy. She had novel homozygous pathogenic frameshift mutation (c.448_451del;p.Pro150Argfs*27) in the PNPO gene. Long-lasting encephalopathy despite well-controlled clinical seizures does neither confirm nor exclude pyridox(am)ine-5-phosphate oxidase deficiency. Normal neurodevelopmental outcome of our patient emphasizes the importance of pyridoxal-5-phosphate treatment. Pyridox(am)ine-5-phosphate oxidase deficiency should be included in the differential diagnosis of Ohtahara syndrome and neonatal myoclonic encephalopathy as a treatable underlying cause. In addition, we reviewed the literature for pyridox(am)ine-5-phosphate oxidase deficiency and summarized herein all confirmed cases.

Pyridoxine-dependent epilepsy is an autosomal recessively inherited disorder of lysine catabolism caused by mutations in the ALDH7A1 gene. We report 2 patients with normal neurocognitive outcome (full-scale IQ of 108 and 74) and their more than 10 years’ treatment outcome on pyridoxine monotherapy. Both patients had specific borderline impairments in visual processing speed. More long-term treatment outcome reports will increase our knowledge about the natural history of the disease.

Pyridoxine dependent epilepsy (PDE) is caused by mutations in the ALDH7A1 gene (PDE-ALDH7A1) encoding α-aminoadipic-semialdehyde-dehydrogenase enzyme in the lysine catabolic pathway resulting in an accumulation of α-aminoadipic-acid-semialdehyde (α-AASA). We present the one-year treatment outcome of a patient on a lysine-restricted diet. Serial cerebral-spinal-fluid (CSF) α-AASA and CSF pipecolic-acid levels showed decreased levels but did not normalize. He had a normal neurodevelopmental outcome on a lysine-restricted diet. Despite normal CSF and plasma tryptophan levels and normal tryptophan intake, he developed mild CSF serotonin deficiency at one year of therapy. Stricter lysine restriction would be necessary to normalize CSF α-AASA levels, but might increase the risks associated with the diet. Patients are at risk of cerebral serotonin deficiency and should be monitored by CSF neurotransmitter measurements.

We report treatment outcome of eleven patients with pyridoxine-dependent epilepsy caused by pathogenic variants in ALDH7A1 (PDE-ALDH7A1). We developed a clinical severity score to compare phenotype with biochemical features, genotype and delays in the initiation of pyridoxine. Clinical severity score included 1) global developmental delay/ intellectual disability; 2) age of seizure onset prior to pyridoxine; 3) current seizures on treatment. Phenotype scored 1-3 = mild; 4-6 = moderate; and 7-9 = severe. Five patients had mild, four patients had moderate, and two patients had severe phenotype. Phenotype ranged from mild to severe in eight patients (no lysine-restricted diet in the infantile period) with more than 10-fold elevated urine or plasma α-AASA levels. Phenotype ranged from mild to moderate in patients with homozygous truncating variants and from moderate to severe in patients with homozygous missense variants. There was no correlation between severity of the phenotype and the degree of α-AASA elevation in urine or genotype. All patients were on pyridoxine, nine patients were on arginine and five patients were on the lysine-restricted diet. 73% of the patients became seizure free on pyridoxine. 25% of the patients had a mild phenotype on pyridoxine monotherapy. Whereas, 100% of the patients, on the lysine-restricted diet initiated within their first 7 months of life, had a mild phenotype. Early initiation of lysine-restricted diet and/or arginine therapy likely improved neurodevelopmental outcome in young patients with PDE-ALDH7A1.

Hereditary spastic paraplegias and related genetically heterogeneous disorders may be difficult to distinguish clinically. The FA2H gene has been associated with autosomal recessive neurodegenerative phenotypes encompassing spastic paraplegia with or without dystonia, and demyelinating leukodystrophy. To date, few individuals with mutations in the FA2H gene have been described. We report a 5-year-old girl of mixed Filipino and Vietnamese origin who presented with progressive lower limb spasticity and periventricular leukomalacia. The clinical diagnosis of FA2H-associated neurodegeneration was confirmed on the basis of 2 novel mutations in compound heterozygosity in the FA2H gene (p.S70L/p.P323L). This family highlights that FA2H-associated disorders may be underrecognized in children with neurodegeneration of many different ethnicities. Magnetic resonance imaging features play an important role as diagnostic clues in this and other hereditary spastic paraplegias. The consideration of this diagnosis is essential in providing families with important information on prognosis, as well as accurate genetic counseling.

Background: GAMT deficiency is an autosomal recessive disorder of creatine biosynthesis resulting in severe neurological complications in untreated patients. Currently available treatment is only successful to stop disease progression, but is not sufficient to reverse neurological complications occurring prior to diagnosis. Normal neurodevelopmental outcome in a patient, treated in the newborn period, highlights the importance of early diagnosis. Methods: Targeted mutation analysis (c.59G>C and c.327G>A) in the GAMT gene by the QIAxcel system and GAA measurement by a novel two-tier method were performed in 3000 anonymized newborn blood dot spot cards. Results: None of the targeted mutations were detected in any newborn. Two novel heterozygous variants (c.283_285dupGTC; p.Val95dup and c.278_283delinsCTCGATGCAC; p.Asp93AlafsX35) were identified by coincidence. Carrier frequency for these insertion/deletion types of GAMT mutations was 1/1475 in this small cohort of newborns. GAA levels were at or above the 99th percentile (3.12μmol/l) in 4 newborns. Second-tier testing showed normal results for 4 newborns revealing 0.1% false positive rate. No GAMT mutations were identified in 4 of the newborns with elevated GAA levels in the first tier testing. Conclusion: This is the first two-tier study to investigate carrier frequency of GAMT deficiency in the small cohort of newborn population to establish evidence base for the first steps toward newborn screening for this treatable neurometabolic disorder. © 2012 Elsevier Inc.

Pyridoxine-dependent epilepsy (PDE) was first described in 1954. The ALDH7A1 gene mutations resulting in α-aminoadipic semialdehyde dehydrogenase deficiency as a cause of PDE was identified only in 2005. Neonatal epileptic encephalopathy is the presenting feature in >50% of patients with classic PDE. We report the case of a 13-month-old girl with profound neonatal hypoglycemia (0.6 mmol/L; reference range >2.4), lactic acidosis (11 mmol/L; reference range A (p.Val278Val), and a novel putative pathogenic missense mutation c.1192G>C (p.Gly398Arg) in the ALDH7A1 gene. She has been seizure-free since 1.5 months of age on treatment with pyridoxine alone. She has motor delay and central hypotonia but normal language and social development at the age of 13 months. This case is the first description of a patient with PDE due to mutations in the ALDH7A1 gene who presented with profound neonatal hypoglycemia and lactic acidosis masquerading as a neonatal-onset gluconeogenesis defect. PDE should be included in the differential diagnosis of hypoglycemia and lactic acidosis in addition to medically refractory neonatal seizures.

We describe two siblings with 3-methylglutaconic aciduria type I with phenotypic heterogeneity. The index case was a 14-year-old female with learning disability, attention deficit-hyperactivity and early onset subclinical leukoencephalopathy. Her 9-year-old brother had severe expressive speech delay and delay in speech sound development with normal cognitive functions. The diagnosis was confirmed by a demonstration of 3-methylglutaconyl-CoA hydratase enzyme deficiency in the cultured skin fibroblasts and homozygous deletion of exons 1–3 within the AUH gene.

Pseudohypoparathyrodism (PHP) is a disorder caused by mutations in the guanine nucleotide-binding α-subunit (GNAS). We sought to determine the genetic origin of PHP1a in one affected family. We identified the previously reported Gsα R231H mutation in family members affected with PHP1a. DNA analysis found that the two clinically affected sons are heterozygous for the mutation. The sons have PHP1a, manifesting obesity, intellectual disability, hypogonadism, hypothyroidism and elevated PTH levels. Initial DNA sequencing did not detect the mutation in either parent. However, their mother displayed some features of PHP, including elevated PTH levels and asymmetrical metacarpal shortening. Using molecular cloning, we detected the mutation at low levels in the mother's leukocyte DNA, consistent with somatic mosaicism and her mildly affected status. Thus, we have identified additional cases of PHP1a caused by the Gsα R231H mutation. In this family, the mother has a milder phenotype due in part to somatic mosaicism, whereas the two affected sons have full PHP1a. Though somatic mosaicism for activating GNAS mutations is known to occur in McCune–Albright syndrome, this is the first report confirming somatic mosaicism for a hypofunctioning GNAS mutation in a PHP kindred. © 2010 Wiley-Liss, Inc.

Twenty three patients with late onset argininosuccinate lyase deficiency (ASLD) were identified during a 27 year period of newborn screening in Austria (1:95600 95 CI = 1:68036 1:162531). One additional patient was identified outside the newborn screening with neonatal hyperammonemia. Long term outcome data were available in 17 patients (median age 13 years) ascertained by newborn screening. Patients were treated with protein restricted diet and oral arginine supplementation during infancy and childhood. IQ was average/above average in 11 (65) low average in 5 (29) and in the mild intellectual disability range in 1 (6) patients. Four patients had an abnormal EEG without evidence of clinical seizures and three had abnormal liver function tests and/or evidence of hepatic steatosis. Plasma citrulline levels were elevated in four patients. Plasma ammonia levels were within normal range prior and after a protein load in all patients. Seven different mutations were identified in the 16 alleles investigated. Four mutations were novel (p.E189G p.R168C p.R126P and p.D423H). All mutations were associated with low argininosuccinate lyase activities (0 15) in red blood cells. Newborn screening might be beneficial in the prevention of chronic neurologic and intellectual sequelae in late onset ASLD but a proportion of benign variants might have contributed to the overall favorable outcome as well. © 2010 Elsevier Inc. All rights reserved.

Objective Folinic acid-responsive seizures and pyridoxine-dependent epilepsy are two treatable causes of neonatal epileptic encephalopathy. The former is diagnosed by characteristic peaks on cerebrospinal fluid (CSF) monoamine metabolite analysis; its genetic basis has remained elusive. The latter is due to alpha-aminoadipic semialdehyde (alpha-AASA) dehydrogenase deficiency, associated with pathogenic mutations in the ALDH7A1 (antiquitin) gene. We report two patients whose CSF showed the marker of folinic acid-responsive seizures, but who responded clinically to pyridoxine. We performed genetic and biochemical testing of samples from these patients, and seven others, to determine the relation between these two disorders. Methods CSF samples were analyzed for the presence of alpha-AASA and pipecolic acid. DNA sequencing of the ALDH7A1 gene was performed. Results Both patients reported here had increased CSF alpha-AASA, CSF pipecolic acid, and known or likely pathogenic mutations in the ALDH7A1 gene, consistent with alpha-AASA dehydrogenase deficiency. Analysis of CSF samples from seven other anonymous individuals diagnosed with folinic acid-responsive seizures showed similar results. Interpretation These results demonstrate that folinic acid-responsive seizures are due to alpha-AASA dehydrogenase deficiency and mutations in the ALDH7A1 gene. Thus, folinic acid-responsive seizures are identical to the major form of pyridoxine-dependent epilepsy. We recommend consideration of treatment with both pyridoxine and folinic acid for patients with alpha-AASA dehydrogenase deficiency, and consideration of a lysine restricted diet. The evaluation of patients with neonatal epileptic encephalopathy, as well as those with later-onset seizures, should include a measurement of alpha-AASA in urine to identify this likely underdiagnosed and treatable disorder.

Aim: To assess the neurological and clinical long-term outcome of patients diagnosed with congenital hyperinsulinism (CHI) in Austria. Patients and Methods: Fourteen patients diagnosed with CHI (1978-2000) were investigated retrospectively by reviewing hospital records. Thirteen of them were evaluated with either a questionnaire or clinical, neurological and biochemical investigations (age at evaluation 4.2- 25.5 years) in a follow-up study in the year 2004. Results: Fifty percent of the patients needed a pancreatectomy. The prevalence of mental retardation was 31%, of epilepsy 15% and of pancreatic insufficiency 14%. None of our patients had developed diabetes mellitus. Additionally the prevalence of obesity was 43% in patients after pancreatectomy. Sixty-nine percent of the patients had no further treatment at the time of follow-up. Conclusion: Despite early diagnosis and intensive treatment, 31% of the patients presented with mental retardation.

Es wird uber einen Patienten mit einer konstitutionellen Deletion am kurzen Arm von Chromosom 4 [del(4)(p16)] und den typischen klinischen Symptomen des Wolf-Hirschhorn-Syndroms (WHS; OMIM # 194190), wie Hypertelorismus, zeltformiger Mund, tief sitzende Ohren, valvulare Aortenstenose, Hodendysplasie und Hypospadie, berichtet. Die psychomotorische Entwicklung wurde durch eine ausgepragte muskulare Hypotonie, beidseitige Innenohrschwerhorigkeit und BNS-Epilepsie kompliziert. Da eine fruhkindliche BNS-Epilepsie laut Literatur bei bisher etwa 50 von 300 Patienten mit WHS beschrieben wurde, sollte das Wolf-Hirschhorn-Syndrom in die Differenzialdiagnose von fruhkindlichen Epilepsiesyndromen, die mit zusatzlichen Dysmorphiezeichen einhergehen, miteinbezogen werden.

Background Pyridoxine-dependent epilepsy (PDE) is caused by mutations in ALDH7A1 (PDE- ALDH7A1 ), which encodes α-aminoadipic semialdehyde dehydrogenase in the lysine catabolic pathway, resulting in accumulation of α-aminoadipic-acid-semialdehyde. Patient Description and Results We present a three-year treatment outcome of a child with PDE- ALDH7A1 on pyridoxine (started at age three weeks of age), lysine-restricted diet (started at age seven months), and arginine supplementation therapy (started at age 26 months). He had a markedly elevated urinary α-aminoadipic-acid-semialdehyde (39.6 mmol/mol of creatinine; reference range = 0 to 2) and compound heterozygous mutations in ALDH7A1 (c.446C>A and c.919C>T). He has been seizure free since the age three weeks. He achieved normal cognitive function at age 3.5 years. He exhibited gross motor delay after the age 13 months. Tryptophan supplementation was added for the mild cerebral serotonin deficiency at the thirteenth month of therapy. Arginine supplementation was added to achieve further decrease in the cerebrospinal fluid α-aminoadipic-acid-semialdehyde levels at the 26th month of therapy. His cerebrospinal fluid α-aminoadipic-acid-semialdehyde levels were markedly decreased on this combined therapy. Conclusions This treatment was well tolerated. Mild cerebral serotonin deficiency was the only biochemical effect with no clinical features. Despite excellent compliance and strict treatment regimen, cerebrospinal fluid α-aminoadipic-acid-semialdehyde levels did not normalize.

Epilepsy is one of the most common neurological disorders in childhood. Epilepsy associated with global developmental delay and cognitive dysfunction is defined as epileptic encephalopathy. Certain inherited metabolic disorders presenting with epileptic encephalopathy can be treated with disease specific diet, vitamin, amino acid or cofactor supplementations. In those disorders, disease specific therapy is successful to achieve good seizure control and improve long-term neurodevelopmental outcome. For this reason, intractable epilepsy with global developmental delay or history of developmental regression warrants detailed metabolic investigations for the possibility of an underlying treatable inherited metabolic disorder, which should be undertaken as first line investigations. An underlying genetic etiology in epileptic encephalopathy has been supported by recent studies such as array comparative genomic hybridization, targeted next generation sequencing panels, whole exome and whole genome sequencing. These studies report a diagnostic yield up to 70%, depending on the applied genetic testing as well as number of patients enrolled. In patients with epileptic encephalopathy, a stepwise approach for diagnostic work-up will help to diagnose treatable inherited metabolic disorders quickly. Application of detailed genetic investigations such as targeted next generation sequencing as second line and whole exome sequencing as third line testing will diagnose underlying genetic disease which will help for genetic counseling as well as guide for prenatal diagnosis. Knowledge of underlying genetic cause will provide novel insights into the pathogenesis of epileptic encephalopathy and pave the ground towards the development of targeted neuroprotective treatment strategies to improve the health outcome of children with epileptic encephalopathy.

Objective Glucose transporter 1 deficiency syndrome is an autosomal, dominantly inherited neurometabolic disorder caused by mutations in the SLC2A1 gene. Decreased glucose transport into the brain results in seizures and cognitive dysfunction. The ketogenic diet is the treatment of choice, but complicated with compliance problems. Stabilization of blood glucose levels by low glycemic index diet and modified high amylopectin cornstarch would provide steady-state glucose transport into the brain to prevent seizures and cognitive dysfunction in patients with glucose transporter 1 deficiency syndrome as an alternative treatment. Patient We report a new glucose transporter 1 deficiency syndrome patient (c.988C>T; p. Arg330X in the SLC2A1 ) treated with modified high amylopectin cornstarch (Glycosade) and low glycemic index diet because of compliance problems with the ketogenic diet. She was diagnosed at 11.5 years of age and was treated with the ketogenic diet between ages 12 and 18 years. Results She was started on modified high amylopectin cornstarch at bedtime and low glycemic index diet with meals and snacks every 3-4 hours. Within the first 6 months of therapy, she improved in her seizures and cognitive functions, but experienced compliance problems afterwards. Neuropsychological assessment was stable at 12 months of therapy. Conclusion This diet was easy to apply compared with the ketogenic diet and resulted in stable neuropsychological functioning of this glucose transporter 1 deficiency syndrome patient. Modified high amylopectin cornstarch and low glycemic index diet might be an alternative treatment in glucose transporter 1 deficiency syndrome patients with compliance problems to the ketogenic diet treatment, but additional patients should be treated to prove usefulness of this new treatment.

BACKGROUND Hyperinsulinism-hyperammonemia syndrome (HI/HA) is a rare autosomal dominant disorder presenting with hypoglycemia and hyperammonemia. It is caused by activating mutations in the GLUD1 gene. CASE REPORTS Three patients from two different centers, a 14-month-old female, a 28-year-old female (mother of the first patient) from Toronto and an unrelated 2.5-year-old male from Vienna, presented with multiple episodes of seizures associated with hypoglycemia. RESULTS All patients had mild to moderate hypoglycemia, inappropriate insulin levels and mild hyperammonemia, thus suggesting a disorder of glutamate dehydrogenase (GDH). Molecular genetic testing of the GLUD1 gene identified heterozygous mutations in all patients (patient 1 and her mother a novel c.1526G>C mutation; patient 3 a known c.809C>G mutation). CONCLUSION We present three new patients with GDH caused by heterozygous mutation in the GLUD1 gene. Mild hyperammonemia and inappropriately elevated insulin levels should suggest a GLUD1 mutation. Early onset hypoglycemia associated with seizures, and especially a good response to diazoxide treatment, should include this disorder in the differential diagnosis of hyperinsulinemic hypoglycemia.

Guanidinoacetate methyltransferase (GAMT) deficiency is a neurodegenerative disease. Although no symptomatic patients on treatment achieved normal neurodevelopment, three asymptomatic newborns were reported with normal neurodevelopmental outcome on neonatal treatment. GAMT deficiency is therefore a candidate for newborn screening programs, but there are no studies for the carrier frequency of this disease in the general population. To determine carrier frequency of GAMT deficiency, we studied the variants in the GAMT gene reported in the Exome Variant Server database and performed functional characterization of missense variants. We used previously cloned GAMT transcript variant 1 (7 missense variants) and cloned a novel GAMT transcript variant 2 (5 missense variants). The latter was used in Exome Variant Server database according to recommendations of the Human Genome Variation Society. There were 4 missense variants (1 previously reported and 3 novel) with low GAMT enzyme activity indicating pathogenicity. Additionally, there was one novel frameshift and one novel nonsense variant likely pathogenic. There was no measurable GAMT enzyme activity in the wild type of GAMT transcript variant 2. We concluded that GAMT transcript variant 2 is not involved in GAMT protein synthesis. For this reason, Human Genome Variation Society should use mutation nomenclature according to the coding region of the GAMT transcript variant 1. The carrier frequency of GAMT deficiency was 0.123 % in the general population. As early diagnosis results in normal neurodevelopmental outcome, GAMT deficiency should be included in newborn screening programs to diagnose individuals at the asymptomatic stage of the disease to prevent permanent neurodevelopmental disability.

Pyridoxine dependent epilepsy (PDE) is caused by mutations in the ALDH7A1 gene encoding α-aminoadipic semialdehyde dehydrogenase. The classic clinical presentation is neonatal seizures responsive only to pyridoxine therapy. White matter abnormalities, corpus callosum agenesis or hypoplasia, megacisterna magna, cortical dysplasia, neuronal heterotopias, intracerebral hemorrhage, and hydrocephalus in neuroimaging have been reported in patients with PDE. We report a new patient with asymmetric progressive ventriculomegaly noted on fetal sonography at 22 weeks’ gestation. Postnatal brain sonography on day 1 and MRI on day 5 confirmed bilateral asymmetric ventriculomegaly caused by bilateral subependymal cysts. Intractable seizures at age 7 days initially responded to phenobarbital. Markedly elevated urinary α-aminoadipic acid semialdehyde levels and compound heterozygous mutations in the ALDH7A1 gene (c.446C>A/c.919C>T) confirmed the diagnosis of PDE caused by ALDH7A1 genetic defect. Despite the presence of structural brain malformations and subependymal cysts, PDE should always be included in the differential diagnosis of neonatal seizures that are refractory to treatment with antiepileptic drugs.

Background Zellweger spectrum disorder is an autosomal recessively inherited multisystem disorder caused by one of the 13 different PEX gene defects resulting in defective peroxisomal assembly and multiple peroxisomal enzyme deficiencies. We report a new patient with late-onset Zellweger spectrum disorder mimicking X-linked adrenoleukodystrophy. Patient Description This 8.5-year-old boy with normal development until 6.5 years of age presented with bilateral sensorineural hearing loss during a school hearing test. He then developed acute-onset diplopia, clumsiness, and cognitive dysfunction at age 7 years. Magnetic resonance imaging of the brain revealed symmetric leukodystrophy, although without gadolinium enhancement. Elevated plasma very long chain fatty acid levels were suggestive of X-linked adrenoleukodystrophy, but his ABCD1 gene had normal coding sequence and dosage. Additional studies of cultured skin fibroblasts were consistent with Zellweger spectrum disorder. Molecular testing identified disease-causing compound heterozygous mutations in the PEX6 gene supporting the Zellweger spectrum disorder diagnosis in this patient. Conclusions We describe a new patient with late-onset Zellweger spectrum disorder caused by PEX6 mutations who presented with an acute neurodegenerative disease course mimicking X-linked adrenoleukodystrophy. This finding provides an additional reason that molecular confirmation is important for the genetic counseling and management of patients with a clinical and biochemical diagnosis of X-linked adrenoleukodystrophy.

Severe methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare autosomal recessively inherited inborn error of folate metabolism. We report a new patient with severe MTHFR deficiency who presented at age 4 months with early onset severe scoliosis associated with severe hypotonia. Markedly decreased MTHFR enzyme activity (0.3 nmoles CHO/mg protein/h; reference range>9) and compound heterozygous mutations (c. 1304T>C; p.Phe435Ser and c.1539dup; p.Glu514Argfs∗24) in the MTHFR gene confirmed the diagnosis. She was treated with vitamin B12, folic acid and betaine supplementation and showed improvements in her developmental milestones and hypotonia. To the best of our knowledge, this is the first patient with MTHFR deficiency reported with severe early onset scoliosis. Despite the late diagnosis and treatment initiation, she showed favorable short-term neurodevelopmental outcome. This case suggests that homocysteine measurement should be included in the investigations of patients with developmental delay, hypotonia and scoliosis within first year of life prior to organizing genetic investigations.

Background and hypothesis Pyridoxine dependent epilepsy (PDE) due to mutations in the ALDH7A1 gene (PDE- ALDH7A1 ) is caused by α-aminoadipic-semialdehyde-dehydrogenase enzyme deficiency in the lysine pathway resulting in the accumulation of α-aminoadipic acid semialdehyde (α-AASA). Classical presentation is neonatal intractable seizures with a dramatic response to pyridoxine. Pyridoxine therapy does not prevent developmental delays in the majority of the patients. We hypothesized that l -arginine supplementation will decrease accumulation of α-AASA by competitive inhibition of lysine transport into the central nervous system and improve neurodevelopmental and neurocognitive functions in PDE- ALDH7A1. Methods A 12-year-old male with PDE- ALDH7A1 was treated with l -arginine supplementation as an innovative therapy. Treatment outcome was monitored by cerebral-spinal-fluid (CSF) α-AASA measurements at baseline, 6th and 12th months of therapy. Neuropsychological assessments were performed at baseline and 12th months of therapy. Results l -arginine therapy was well tolerated without side effects. CSF α-AASA was decreased 57% at 12th months of therapy. Neuropsychological assessments revealed improvements in general abilities index from 108 to 116 and improvements in verbal and motor functioning at 12th months of therapy. Conclusion The short-term treatment outcome of this novel l -arginine supplementation therapy for PDE- ALDH7A1 was successful for biochemical and neurocognitive improvements.

International audience; Guanidinoacetate methyltransferase deficiency (GAMT-D) is an autosomal recessively inherited disorder of creatine biosynthesis. Creatine deficiency on cranial proton magnetic resonance spectroscopy, and elevated guanidinoacetate levels in body fluids are the biomarkers of GAMT-D. In 74 patients, 50 different mutations in the GAMT gene have been identified with missense variants being the most common. Clinical and biochemical features of the patients with missense variants were obtained from their physicians using a questionnaire. In 20 patients, 17 missense variants, 25% had a severe, 55% a moderate, and 20% a mild phenotype. The effect of these variants on GAMT enzyme activity was overexpressed using primary GAMT-D fibroblasts: 17 variants retained no significant activity and are therefore considered pathogenic. Two additional variants, c.22C\textgreaterA (p.Pro8Thr) and c.79T\textgreaterC (p.Tyr27His) (the latter detected in control cohorts) are in fact not pathogenic as these alleles restored GAMT enzyme activity, although both were predicted to be possibly damaging by in silico analysis. We report 13 new patients with GAMT-D, six novel mutations and functional analysis of 19 missense variants, all being included in our public LOVD database. Our functional assay is important for the confirmation of the pathogenicity of identified missense variants in the GAMT gene.

Background Guanidinoacetate methyltransferase deficiency is an autosomal recessively inherited disorder of creatine biosynthesis. We report a new patient with guanidinoacetate methyltransferase deficiency and her >3-year treatment outcome. Patient This is a 6-year-old girl who was diagnosed with guanidinoacetate methyltransferase deficiency at the age of 28 months. She presented with moderate global developmental delay, one afebrile seizure, and hypotonia between 6 and 18 months of life. She was treated with creatine and ornithine supplementation and a strict arginine-restricted diet for 42 months. Results Mutation analysis (compound heterozygous mutations, a known c.327G>A and a novel c.58dupT [p.Trp20LeufsX65]) and enzyme studies in primary fibroblasts confirmed the diagnosis. After 33 months of therapy, her cerebrospinal fluid guanidinoacetate level decreased from 47 to 5.3 times the normal level. Brain creatine by proton magnetic resonance spectroscopy increased by >75% but did not normalize in the basal ganglia and white matter after 3 years of therapy. Additional treatment with sodium benzoate for 17 months did not further improve plasma guanidinoacetate levels, which questions the relevance of this therapy. Conclusion Treatment did not improve moderate intellectual disability or normalize guanidinoacetate accumulation in the central nervous system.

We collected data on 48 patients from 38 families with guanidinoacetate methyltransferase (GAMT) deficiency. Global developmental delay/intellectual disability (DD/ID) with speech/language delay and behavioral problems as the most affected domains was present in 44 participants, with additional epilepsy present in 35 and movement disorder in 13. Treatment regimens included various combinations/dosages of creatine-monohydrate, L-ornithine, sodium benzoate and protein/arginine restricted diets. The median age at treatment initiation was 25.5 and 39 months in patients with mild and moderate DD/ID, respectively, and 11 years in patients with severe DD/ID. Increase of cerebral creatine and decrease of plasma/CSF guanidinoacetate levels were achieved by supplementation with creatine-monohydrate combined with high dosages of t-ornithine and/or an arginine-restricted diet (250 mg/kg/d L-arginine). Therapy was associated with improvement or stabilization of symptoms in all of the symptomatic cases. The 4 patients treated younger than 9 months had normal or almost normal developmental outcomes. One with inconsistent compliance had a borderline IQ at age 8.6 years. An observational GAMT database will be essential to identify the best treatment to reduce plasma guanidinoacetate levels and improve long-term outcomes. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.

The standard of care for first-tier clinical investigation of the aetiology of congenital malformations and neurodevelopmental disorders is chromosome microarray analysis (CMA) for copy-number variations (CNVs), often followed by gene(s)-specific sequencing searching for smaller insertion–deletions (indels) and single-nucleotide variant (SNV) mutations. Whole-genome sequencing (WGS) has the potential to capture all classes of genetic variation in one experiment; however, the diagnostic yield for mutation detection of WGS compared to CMA, and other tests, needs to be established. In a prospective study we utilised WGS and comprehensive medical annotation to assess 100 patients referred to a paediatric genetics service and compared the diagnostic yield versus standard genetic testing. WGS identified genetic variants meeting clinical diagnostic criteria in 34% of cases, representing a fourfold increase in diagnostic rate over CMA (8%; P value=1.42E−05) alone and more than twofold increase in CMA plus targeted gene sequencing (13%; P value=0.0009). WGS identified all rare clinically significant CNVs that were detected by CMA. In 26 patients, WGS revealed indel and missense mutations presenting in a dominant (63%) or a recessive (37%) manner. We found four subjects with mutations in at least two genes associated with distinct genetic disorders, including two cases harbouring a pathogenic CNV and SNV. When considering medically actionable secondary findings in addition to primary WGS findings, 38% of patients would benefit from genetic counselling. Clinical implementation of WGS as a primary test will provide a higher diagnostic yield than conventional genetic testing and potentially reduce the time required to reach a genetic diagnosis.

Objective: To evaluate the efficacy and safety of dietary lysine restriction as an adjunct to pyridoxine therapy on biochemical parameters, seizure control, and developmental/cognitive outcomes in children with pyridoxine-dependent epilepsy (PDE) caused by antiquitin (ATQ) deficiency. Methods: In this observational study, seven children with confirmed ATQ deficiency were started on dietary lysine restriction with regular nutritional monitoring. Biochemical outcomes were evaluated using pipecolic acid and alpha-aminoadipic semialdehyde (AASA) levels in body fluids; developmental/cognitive outcomes were evaluated using age-appropriate tests and parental observations. Results: Lysine restriction was well tolerated with good compliance; no adverse events were reported. Reduction in biomarker levels (measurement of the last value before and first value after initiation of dietary lysine restriction) ranged from 20 to 67% for plasma pipecolic acid, 13 to 72% for urinary AASA, 45% for plasma AASA and 42% for plasma P6C. For the 1 patient in whom data were available and who showed clinical deterioration upon interruption of diet, cerebrospinal fluid levels decreased by 87.2% for pipecolic acid and 81.7% for AASA Improvement in age-appropriate skills was observed in 4 out of 5 patients showing pre-diet delays, and seizure control was maintained or improved in 6 out 7 children. Conclusions: This observational study provides Level 4 evidence that lysine restriction is well tolerated with significant decrease of potentially neurotoxic biomarkers in different body compartments, and with the potential to improve developmental outcomes in children with PDE caused by ATQ deficiency. To generate a strong level of evidence before this potentially burdensome dietary therapy becomes the mainstay treatment, we have established: an international PDE consortium to conduct future studies with an all-inclusive integrated study design; a website containing up-to-date information on PDE; a methodological toolbox; and an online registry to facilitate the participation of interested physicians, scientists, and families in PDE research. (C) 2012 Elsevier Inc. All rights reserved

BACKGROUND The urea cycle defect argininosuccinate lyase (ASL) deficiency has a large spectrum of presentations from highly severe to asymptomatic. Enzyme activity assays in red blood cells or fibroblasts although diagnostic of the deficiency fail to discriminate between severe mild or asymptomatic cases. Mutation/phenotype correlation studies are needed to characterize the effects of individual mutations on the activity of the enzyme. METHODS Bacterial in vitro expression studies allowed the enzyme analysis of purified mutant ASL proteins p.I100T (c.299 T?>?C) p.V178M (c.532 G?>?A) p.E189G (c.566A?>?G) p.Q286R (c.857A?>?G) p.K315E (c.943A?>?G) p.R379C (c.1135 C?>?T) and p.R385C (c.1153 C?>?T) in comparison to the wildtype protein. RESULTS In the bacterial in vitro expression system ASL wild type protein was successfully expressed. The known classical p.Q286R the novel classical p.K315E and the known mutations p.I100T p.E189G and p.R385C which all have been linked to a mild phenotype showed no significant residual activity. There was some enzyme activity detected with the p.V178M (5 of wild type) and p.R379C (10 of wild type) mutations in which K(m) values for argininosuccinic acid differed significantly from the wild type ASL protein. CONCLUSION The bacterially expressed enzymes proved that the mutations found in patients and studied here indeed are detrimental. However as in the case of red cell ASL activity assays some mutations found in genetically homozygous patients with mild presentations resulted in virtual loss of enzyme activity in the bacterial system suggesting a more protective environment for the mutant enzyme in the liver than in the heterologous expression system and/or in the highly dilute assays utilized here.

A 4-year-old female with history of developmental regression and autistic features was diagnosed with guanidinoacetate methyltransferase deficiency at age 21 months. Upon treatment, she showed improvements in her developmental milestones, sensorial-neural hearing loss and brain atrophy on cranial-MRI. The creatine/choline ratio increased 82% in basal ganglia and 88% in white matter on cranial MR-spectroscopy. The CSF guanidinoacetate decreased 80% after six months of ornithine and creatine supplementation and an additional 8% after 18 months of additional arginine restricted diet. We report the most favorable clinical and biochemical outcome on treatment in our patient.

Antiquitin (ATQ) deficiency is the main cause of pyridoxine dependent epilepsy characterized by early onset epileptic encephalopathy responsive to large dosages of pyridoxine. Despite seizure control most patients have intellectual disability. Folinic acid responsive seizures (FARS) are genetically identical to ATQ deficiency. ATQ functions as an aldehyde dehydrogenase (ALDH7A1) in the lysine degradation pathway. Its deficiency results in accumulation of α-aminoadipic semialdehyde (AASA), piperideine-6-carboxylate (P6C) and pipecolic acid, which serve as diagnostic markers in urine, plasma, and CSF. To interrupt seizures a dose of 100 mg of pyridoxine-HCl is given intravenously, or orally/enterally with 30 mg/kg/day. First administration may result in respiratory arrest in responders, and thus treatment should be performed with support of respiratory management. To make sure that late and masked response is not missed, treatment with oral/enteral pyridoxine should be continued until ATQ deficiency is excluded by negative biochemical or genetic testing. Long-term treatment dosages vary between 15 and 30 mg/kg/day in infants or up to 200 mg/day in neonates, and 500 mg/day in adults. Oral or enteral pyridoxal phosphate (PLP), up to 30 mg/kg/day can be given alternatively. Prenatal treatment with maternal pyridoxine supplementation possibly improves outcome. PDE is an organic aciduria caused by a deficiency in the catabolic breakdown of lysine. A lysine restricted diet might address the potential toxicity of accumulating αAASA, P6C and pipecolic acid. A multicenter study on long term outcomes is needed to document potential benefits of this additional treatment. The differential diagnosis of pyridoxine or PLP responsive seizure disorders includes PLP-responsive epileptic encephalopathy due to PNPO deficiency, neonatal/infantile hypophosphatasia (TNSALP deficiency), familial hyperphosphatasia (PIGV deficiency), as well as yet unidentified conditions and nutritional vitamin B6 deficiency. Commencing treatment with PLP will not delay treatment in patients with pyridox(am)ine phosphate oxidase (PNPO) deficiency who are responsive to PLP only.

Nonketotic hyperglycinemia (NKH) is an inborn error of the glycine metabolism. A 9-year-old boy with learning disability and intermittent choreoathetosis during febrile illnesses had elevated plasma glycine level and CSF/plasma glycine ratio (0.044) and a novel homozygous missense mutation (c.605C>T; p.Ala202Val) in the GLDC gene, confirming the diagnosis of NKH. This is the first report of late-onset NKH with a confirmed underlying genetic defect. NKH should be in the differential diagnosis of intermittent choreoathetosis.

Objective: Vanishing white matter (VWM) is an autosomal recessive leukoencephalopathy characterized by slowly progressive ataxia and spasticity with additional stress-provoked episodes of rapid and major deterioration. The disease is caused by mutations in the genes encoding the subunits of eukaryotic initiation factor 2B, which is pivotal in translation of mRNAs into proteins. The disease onset, clinical severity, and disease course of VWM vary greatly. The influence of genotype and gender on the phenotype is unclear. Methods: From our database of 184 patients with VWM, we selected those with the following mutations in the gene EIF2B5: p.Arg113His in the homozygous state (n = 23), p.Arg113His in the compound-heterozygous state (n = 49), p.Thr91Ala in the homozygous state (n = 8), p.Arg113His/p.Arg339any (n = 9), and p.Thr91Ala/p.Arg339any (n = 7). We performed a cross-sectional observational study. Evaluated clinical characteristics were gender, age at onset, age at loss of walking without support, and age at death. Means, male/female ratios, and Kaplan-Meier curves were compared. Results: Patients homozygous for p.Arg113His had a milder disease than patients compound heterozygous for p.Arg113His and patients homozygous for p.Thr91Ala. Patients with p.Arg113His/p.Arg339any had a milder phenotype than patients with p.Thr91Ala/p.Arg339any. Overall, females tended to have a milder disease than males. Conclusions: The clinical phenotype in VWM is influenced by the combination of both mutations. Females tend to do better than males. Copyright © 2010 by AAN Enterprises, Inc.

A female heterozygous for a novel, disease causing, missense mutation in the X-linked cerebral creatine transporter (SLC6A8) gene (c.1067G>T, p.Gly356Val) presented with intractable epilepsy, mild intellectual disability and moderately reduced cerebral creatine levels. Treatment with creatine monohydrate, to enhance cerebral creatine transport, combined with L-arginine and L-glycine, to enhance cerebral creatine synthesis, resulted in complete resolution of seizures. Heterozygous SLC6A8 deficiency is a potentially treatable condition and should be considered in females with intractable epilepsy and developmental delay/intellectual disability.