小坂 仁

Dynamin 1 (DNM1) is a large guanosine triphosphatase involved in clathrin-mediated endocytosis. In recent studies, de novo mutations in DNM1 have been identified in five individuals with epileptic encephalopathy. In this study, we report two patients with early onset epileptic encephalopathy possessing de novo DNM1 mutations. Using whole exome sequencing, we detected the novel mutation c.127G>A (p.Gly43Ser) in a patient with Lennox-Gastaut syndrome, and a recurrent mutation c.709C>T (p.Arg237Trp) in a patient with West syndrome. Structural consideration of DNM1 mutations revealed that both mutations would destabilize the G domain structure and impair nucleotide binding, dimer formation, and/or GTPase activity of the G domain. These and previous cases of DNM1 mutations were reviewed to verify the phenotypic spectrum. The main clinical features of DNM1 mutations include intractable seizures, intellectual disability, developmental delay, and hypotonia. Most cases showed development delay before the onset of seizures. A patient carrying p.Arg237Trp in this report showed a different developmental status from that of a previously reported case, together with characteristic extrapyramidal movement.

Recently, de novo KIF1A mutations were identified in patients with intellectual disability, spasticity and cerebellar atrophy and/or optic nerve atrophy. In this study, we analyzed a total of 62 families, including 68 patients with genetically unsolved childhood cerebellar atrophy, by whole-exome sequencing (WES). We identified five de novo missense KIF1A mutations, including only one previously reported mutation (p.Arg316Trp). All the mutations are located in the motor domain of KIF1A. In all patients, initial symptom onset was during the infantile period, and included developmental delay in three patients and gait disturbance in two. Thereafter, they showed gait disturbances, exaggerated deep tendon reflexes, cerebellar symptoms and cerebellar atrophy on brain magnetic resonance imaging. Four patients showed lower limb spasticity, upper limb clumsiness and visual disturbances. Nerve conduction study revealed peripheral neuropathy in three patients. This study further delineates clinical features of de novo KIF1A mutations. Genetic testing of KIF1A should be considered in children with developmental delay, cerebellar atrophy and pyramidal features.

Objective: We investigated a correlation between a mutation in the SLC2A1 gene and functional disorders in Glucose transporter I deficiency syndrome (GLUT1DS). Methods: We performed direct sequence analysis of SLC2A1 in a severe GLUT1DS patient and identified a novel frame shift mutation, c.906_907insG, p.V303fs. We created a plasmid vector carrying the c.906_907insG mutation, as well as A405D or R333W in the SLC2A1, which are found in patients with mild and moderate GLUT1DS severity, respectively. We transiently expressed these mutants and wild type SLC2A1 plasmids in a human embryonic kidney cell line (HEK293), and performed immunoblotting, immunofluorescence, and enzymatic photometric 2-deoxyglucose (2DG) uptake assays. Results: GLUT1 was not detected after transient expression of the SLC2A1 plasmid carrying c.906_907insG by either immunoblotting or immunofluorescence. The degree of glucose transport reduction as determined by enzymatic photometric 2DG assay uptake correlated with disease severity. Conclusions: Enzymatic photometric 2DG uptake study appears to be a suitable functional assay to predict the effect of SLC2A1 mutations on GLUT1 transport. (C) 2015 Elsevier Inc. All rights reserved.

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) at onset manifests an early seizure (ES) usually lasting more than 30 min. Following ES, some patients exhibit almost clear consciousness with no neurological symptoms, and no MRI abnormality for a few days, which may lead to an initial misdiagnosis of prolonged febrile seizures (PFS). To allow an early diagnosis of AESD, we retrospectively analyzed clinical manifestations, laboratory data, and radiologic and EEG findings in patients with AESD (n = 62) having ES of over 30 min, and ones with PFS (n = 54), using logistic regression analyses. Multivariate logistic regression analysis revealed that an age below 1.5 years and a Glasgow Coma Scale score of 14 or less than 14 (Japan Coma Scale score of 1 or higher) were high risk factors of developing AESD. We proposed an AESD prediction score system consisting of consciousness level, age, duration of convulsions, enforcement of mechanical intubation, and aspartate aminotransferase, blood glucose and creatinine levels (full score: 9), the mean scores in AESD and PFS being 5.9 and 1.8, which were significantly different (p < 0.001). We herein propose a scoring system for differentiating patients with AESD and PFS around the time of ES (score of 4 or more than 4 suggesting AESD), which may contribute to early therapeutic intervention and an improved neurologic outcome. (C) 2015 Elsevier B.V. All rights reserved.

KCNT1 mutations have been found in epilepsy of infancy with migrating focal seizures (EIMFS; also known as migrating partial seizures in infancy), autosomal dominant nocturnal frontal lobe epilepsy, and other types of early onset epileptic encephalopathies (EOEEs). We performed KCNT1-targeted next-generation sequencing (207 samples) and/or whole-exome sequencing (229 samples) in a total of 362 patients with Ohtahara syndrome, West syndrome, EIMFS, or unclassified EOEEs. We identified nine heterozygous KCNT1 mutations in 11 patients: nine of 18 EIMFS cases (50%) in whom migrating foci were observed, one of 180 West syndrome cases (0.56%), and one of 66 unclassified EOEE cases (1.52%). KCNT1 mutations occurred de novo in 10 patients, and one was transmitted from the patient's mother who carried a somatic mosaic mutation. The mutations accumulated in transmembrane segment 5 (2/9, 22.2%) and regulators of K+ conductance domains (7/9, 77.8%). Five of nine mutations were recurrent. Onset ages ranged from the neonatal period (<1month) in five patients (5/11, 45.5%) to 1-4months in six patients (6/11, 54.5%). A generalized attenuation of background activity on electroencephalography was seen in six patients (6/11, 54.5%). Our study demonstrates that the phenotypic spectrum of de novo KCNT1 mutations is largely restricted to EIMFS.

Schwartz-Jampel syndrome (SJS) type 1 is characterized by short stature, myotonia, and chondrodysplasia, and is caused by partial loss-of-function mutations in HSPG2 encoding perlecan. Six missense mutations have been reported in SJS to date and only one has been characterized using a recombinant protein. We report an 11-year-old Japanese boy with SJS, who shows "rigid" walking with less flexion of knees/ankles and protruded mouth. His intelligence is normal. We identified by whole genome resequencing a heterozygous missense p.Leu1088Pro in domain III-2 and a heterozygous nonsense p.G1n3061Ter in domain IV of perlecan. Expression studies revealed that p.Leu1088Pro markedly reduces the cellular expression of domain III-2 and almost nullifies its secretion into the culture medium. As five of the seven missense mutations in SJS affect domain III of perlecan, domain III is likely to be essential for secretion of perlecan into the extracellular space. (C) 2015 Elsevier B.A. All rights reserved.

We evaluated outcomes of 56-week stiripentol use with valproate and clobazam for Dravet syndrome. Of 24 patients, 22 experienced stiripentol-related adverse events. No patients discontinued stiripentol due to adverse events. Seizure frequency decreased by ≥50% in 13 patients with 2 remaining seizure-free. Stiripentol adjunctive therapy has a favorable long-term risk-benefit profile. Background: We have previously shown the benefits of short-term add-on stiripentol therapy for Dravet syndrome inadequately controlled by clobazam and valproate in Japanese patients. We report here the outcomes of long-term stiripentol use. Methods: Patients with Dravet syndrome having ≥4 clonic/tonic-clonic seizures per 30 days while on clobazam and valproate (with or without bromide) received add-on stiripentol for 16 weeks. Those benefiting from stiripentol (50. mg/kg/day up to 2500. mg/day) continued the therapy for additional up to 40 weeks. Responders were defined as those whose clonic/tonic-clonic seizures became ≤50% frequent as compared to baseline. Results: Of 24 patients starting stiripentol, 21 received the drug for &gt 16 weeks and 19 completed the study. At the endpoint, the responder rate was 54%, with 2 patients remaining clonic/tonic-clonic seizure-free. Twenty-two patients experienced stiripentol-related adverse events, with two having severe ones. They included somnolence (79%), loss of appetite (67%), ataxia (58%), and elevated gamma-glutamyltransferase (38%). No adverse events led to study discontinuation, but 19 patients required dose reduction for stiripentol and/or either antiepileptic drug combined. Stiripentol dose reduction was done in 9 patients, mostly due to somnolence or loss of appetite. Conclusions: During adjunctive stiripentol use with clobazam and valproate, careful monitoring for adverse events such as somnolence and loss of appetite is recommended, and dose reduction may become needed for any of the antiepileptics. Despite the need for safety precautions, the durable responses to stiripentol for up to 56 weeks suggest that the drug is effective as an adjunct to clobazam and valproate for the treatment of Dravet syndrome.

Mitochondria are key organelles implicated in a variety of processes related to energy and free radical generation, the regulation of apoptosis, and various signaling pathways. Mitochondrial dysfunction increases cellular oxidative stress and depletes ATP in a variety of inherited mitochondrial diseases and also in many other metabolic and neurodegenerative diseases. Mitochondrial diseases are characterized by the dysfunction of the mitochondrial respiratory chain, caused by mutations in the genes encoded by either nuclear DNA or mitochondrial DNA. We have hypothesized that chemicals that increase the cellular ATP levels may ameliorate the mitochondrial dysfunction seen in mitochondrial diseases. To search for the potential drugs for mitochondrial diseases, we screened an in-house chemical library of indole-3-acetic-acid analogs by measuring the cellular ATP levels in Hep3B human hepatocellular carcinoma cells. We have thus identified mitochonic acid 5 (MA-5), 4-(2,4-difluorophenyl)-2-(1H-indol-3-yl)-4-oxobutanoic acid, as a potential drug for enhancing ATP production. MA-5 is a newly synthesized derivative of the plant hormone, indole-3-acetic acid. Importantly, MA-5 improved the survival of fibroblasts established from patients with mitochondrial diseases under the stress-induced condition, including Leigh syndrome, MELAS (myopathy encephalopathy lactic acidosis and stroke-like episodes), Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. The improved survival was associated with the increased cellular ATP levels. Moreover, MA-5 increased the survival of mitochondrial disease fibroblasts even under the inhibition of the oxidative phosphorylation or the electron transport chain. These data suggest that MA-5 could be a therapeutic drug for mitochondrial diseases that exerts its effect in a manner different from anti-oxidant therapy.

Mitochondria are key organelles implicated in a variety of processes related to energy and free radical generation, the regulation of apoptosis, and various signaling pathways. Mitochondrial dysfunction increases cellular oxidative stress and depletes ATP in a variety of inherited mitochondrial diseases and also in many other metabolic and neurodegenerative diseases. Mitochondrial diseases are characterized by the dysfunction of the mitochondrial respiratory chain, caused by mutations in the genes encoded by either nuclear DNA or mitochondrial DNA. We have hypothesized that chemicals that increase the cellular ATP levels may ameliorate the mitochondrial dysfunction seen in mitochondrial diseases. To search for the potential drugs for mitochondrial diseases, we screened an in-house chemical library of indole-3-acetic-acid analogs by measuring the cellular ATP levels in Hep3B human hepatocellular carcinoma cells. We have thus identified mitochonic acid 5 (MA-5), 4-(2,4-difluorophenyl)-2-(1H-indol-3-yl)-4-oxobutanoic acid, as a potential drug for enhancing ATP production. MA-5 is a newly synthesized derivative of the plant hormone, indole-3-acetic acid. Importantly, MA-5 improved the survival of fibroblasts established from patients with mitochondrial diseases under the stress-induced condition, including Leigh syndrome, MELAS (myopathy encephalopathy lactic acidosis and stroke-like episodes), Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. The improved survival was associated with the increased cellular ATP levels. Moreover, MA-5 increased the survival of mitochondrial disease fibroblasts even under the inhibition of the oxidative phosphorylation or the electron transport chain. These data suggest that MA-5 could be a therapeutic drug for mitochondrial diseases that exerts its effect in a manner different from anti-oxidant therapy.

Vanishing white matter disease (VWM)/childhood ataxia with central hypomyelination (CACH) is an autosomal recessive leukoencephalopathy caused by mutations in one of five genes, EIF2B1-5, encoding the 5 subunits of eukaryotic translation initiation factor 2B (eIF2B). The classical phenotype is characterized by early childhood onset and chronic progressive neurological deterioration with cerebellar ataxia, spasticity, optic atrophy and epilepsy. However, the onset of disease varies from antenatal period to adulthood. Cree leukoencephalopathy (CLE) is a severe variant of VWM and caused by a homozygous mutation (R195H) in the EIF2B5 gene. The patient reported in this study developed lethargy, vomiting and seizure 3 days after an oral poliovirus vaccination at the age of 4 months. She presented with rapid neurological deterioration within a month of onset. Brain MRI showed abnormal white matter intensity. Whole-exome sequencing identified two heterozygous mutations in the EIF2B5 gene: a known mutation, c.584G>A (R195H, which is homozygous in CLE), and a novel mutation, c.1223T>C (I408T, which resides in the "I-patch"). Mutations in the "I-patch" encoded region of eIF2B epsilon may be related to an early-infantile onset phenotype. This patient exhibits an early-infantile onset and progressive disease course resembling CLE, suggesting a severe functional disruption of eIF2B epsilon caused by R195H as well as by I408T mutations. (C) 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Mutations in the inositol 1,4,5-triphosphate receptor type 1 gene (ITPR1) have been identified in families with early-onset spinocerebellar ataxia type 29 (SCA29) and late-onset SCA15, but have not been found in sporadic infantile-onset cerebellar ataxia. We examined if mutations of ITPR1 are also involved in sporadic infantile-onset SCA. Sixty patients with childhood-onset cerebellar atrophy of unknown etiology and their families were examined by whole-exome sequencing. We found de novo heterozygous ITPR1 missense mutations in four unrelated patients with sporadic infantile-onset, nonprogressive cerebellar ataxia. Patients displayed nystagmus, tremor, and hypotonia from very early infancy. Nonprogressive ataxia, motor delay, and mild cognitive deficits were common clinical findings. Brain magnetic resonance imaging revealed slowly progressive cerebellar atrophy. ITPR1 missense mutations cause infantile-onset cerebellar ataxia. ITPR1-related SCA includes sporadic infantile-onset cerebellar ataxia as well as SCA15 and SCA29.

Myoclonus-dystonia syndrome (MDS) is a rare autosomal-dominant movement disorder characterized by brief, frequently alcohol-responsive myoclonic jerks that begin in childhood or early adolescence, caused by mutations in the epsilon-sarcoglycan gene (SGCE). The patient was a 6-year-old boy. At 2 years 8 months, he had abnormal movement when he ran due to dystonia of his left leg. At 3 years 5 months, he exhibited dystonia and myoclonic movement of his arms when eating. Myoclonus was likely to develop when he felt anxiety or exhaustion. Genomic DNA showed a heterozygous mutation in SGCE (c.109 + 1 G > T). His father and uncle with the same mutation also experienced milder dystonia or myoclonic movements. SGCE mutation can cause a broad range of clinical symptoms between and within families. We should consider MDS as a differential diagnosis for patients with paroxysmal walking abnormalities and/or myoclonic movements.

Pyridoxine-dependent epilepsy (PDE) is an autosomal recessive disorder characterized by early onset and recurrent seizures that can be controlled by a high dose of pyridoxine. PDE is caused by mutations in ALDH7A1, which encodes antiquitin. Antiquitin converts a-aminoadipic semialdehyde to a-aminoadipic acid. Seizure recurrence after pyridoxine withdrawal is a criterion for diagnosis, but PDE can be diagnosed conclusively by genetic testing for mutations in the ALDH7A1 gene. In this case study, we report the long-term follow-up of a patient suspected with PDE. She experienced prolonged generalized tonic seizures and was hospitalized in an intensive care unit following pyridoxine withdrawal. Later, we identified a compound heterozygous mutation, c.1216G>A, p.Gly406Arg, and a novel splice donor site mutation, IVS9+5G>A. Confirmation of these mutations would have prevented an unsafe withdrawal test. This case suggests the importance of the genetic determination of PDE to avoid the diagnostic withdrawal of pyridoxine. (C) 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

The BCAP31 gene is located between SLC6A8, associated with X-linked creatine transporter deficiency, and ABCD1, associated with X-linked adrenoleukodystrophy. Recently, loss-of-function mutations in BCAP31 were reported in association with severe developmental delay, deafness and dystonia. We characterized the break points in eight patients with deletions of SLC6A8, BCAP31 and/or ABCD1 and studied the genotype-phenotype correlations. The phenotype in patients with contiguous gene deletions involving BCAP31 overlaps with the phenotype of isolated BCAP31 deficiency. Only deletions involving both BCAP31 and ABCD1 were associated with hepatic cholestasis and death before 1year, which might be explained by a synergistic effect. Remarkably, a patient with an isolated deletion at the 3′-end of SLC6A8 had a similar severe phenotype as seen in BCAP31 deficiency but without deafness. This might be caused by the disturbance of a regulatory element between SLC6A8 and BCAP31.

Objective: The objective of this study was to investigate stiripentol (STP) administration in cases of Dravet syndrome (DS) by comparing CYP2C19 allelic polymorphisms with the clinical effects of STP, including plasma concentrations of concomitant drugs and adverse effects of STP. Materials and methods: Eleven cases of DS cases were included. Demographic and clinical characteristics of the cases (age at the study period, body weight, mean dose and plasma concentration of valproate acid (VPA)/clobazam (CLB) off and on STP, mean plasma concentration of norclobazam (N-CLB) off and on STP, degree of seizure reduction, and adverse effects of STP) were examined with each CYP2C19 polymorphism. Results: There were 3 cases of DS with wild type, 6 with intermediate type, and 2 with poor type of CYP2C19 polymorphisms. The N-CLB coneentration/CLB dose ratio and N-CLB/CLB concentration ratio off STP were significantly higher in poor metabolizers. Three (37%) of 8 cases showed no effectiveness of STP regardless of the N-CLB concentration increase, and 1 (33%) of 3 cases showed effectiveness of STP regardless of N-CLB concentration decrease. In total, 6 (54%) of 11 cases with DS had >50% reduction in seizure frequency without significant differences in CYP2C19 polymorphisms. Conclusion: This study demonstrated an effect of CYP2C19 polymorphisms on STP administration in Japanese cases of DS. There were cases of seizure reduction regardless of N-CLB concentration decrease on STP, which suggests a significant anti-convulsant action of STP. N-CLB concentration decrease on STP was observed in 1 case with ketogenic diet and 2 cases with *3 allelic polymorphisms of CYP2C19. (C) 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Aminoacylation is the process of attaching amino acids to their cognate tRNA, and thus is essential for the translation of mRNA into protein. This direct interaction of tRNA with amino acids is catalyzed by aminoacyl-tRNA synthetases. Using whole-exome sequencing, we identified compound heterozygous mutations [c.169T > C (p.Tyr57His) and c.1485dup (p.Lys496*)] in QARS, which encodes glutaminyl-tRNA synthetase, in two siblings with early-onset epileptic encephalopathy (EOEE). Recessive mutations in QARS, including the loss-of-function missense mutation p.Tyr57His, have been reported to cause intractable seizures with progressive microcephaly. The p.Lys496* mutation is novel and causes truncation of the QARS protein, leading to a deletion of part of the catalytic domain and the entire anticodon-binding domain. Transient expression of the p.Lys496* mutant in neuroblastoma 2A cells revealed diminished and aberrantly aggregated expression, indicating the loss-of-function nature of this mutant. Together with the previous report, our data suggest that abnormal aminoacylation is one of the underlying pathologies of EOEE.

クレアチントランスポーター欠損症は, 筋緊張低下, 知的障害とけいれんを特徴とするX連鎖劣性遺伝性疾患である. 本邦3家系目を経験したので報告する. 発端者は8歳男児. 重度知的障害とけいれんを認めた. 2名の兄にてんかんと重度知的障害を認め, 長兄は17歳で突然死した. 尿中クレアチン／クレアチニン比上昇, 頭部MRスペクトロスコピーでクレアチンピーク低下, <i>SLC6A8</i>遺伝子解析でc.1661 C>T;p.Pro554Leuの既報告ミスセンス変異を認め, 確定診断した. 兄にも同じ変異があり, 母はヘテロ接合変異を認めた. 知的障害, けいれんや発達障害等を認め, X連鎖劣性遺伝を示唆する男児例では尿中クレアチン／クレアチニン比の測定をすることが重要である.

Creatine transporter deficiency (CRTR-D) is an X-hnked disorder characterized by hypotonia, developmental delay, and seizures. We report the third Japanese family with CRTR-D. The proband was an 8-year-old boy who presented with hypotonia, severe intellectual disability and two episodes of seizures associated with/without fever Among 7 siblings (4 males, 3 females), the eldest brother had severe intellectual disability, epilepsy, and sudden death at 17 years of age, while 18-year-old third elder brother had severe intellectual disability, autism, and drug-resistant epilepsy The proband's urinary creatine/creatinine ratio was increased A reduced creatine peak on brain magnetic resonance spectroscopy and a known pathogenic mutation in the SLC6A8 gene (c.1661 C&gt T,p.Pro554Leu) confirmed the diagnosis of CRTR-D The same mutation was found in the third elder brother. Their mother was a heterozygote. Symptoms of CRTR-D are non-specific. Urinary creatine/creatinine ratio should be measured in patients with hypotonia, developmental delay, seizure and autism whose family history indicates an X-linked inheritance.

Creatine transporter deficiency (CTD) is an example of X-linked intellectual disability syndromes, caused by mutations in SLC6A8 on Xq28. Although this is the second most frequent genetic cause of intellectual disabilities in Europe or America after Fragile X syndrome, information on the morbidity of this disease is limited in Japan. Using the HPLC screening method we have established recently, we examined samples of urine of 105 patients (73 males and 32 females) with developmental disabilities at our medical center. And we have found a family with three ID boys with a novel missense mutation in SLC6A8. This is the second report of a Japanese family case of CTD. A systematic diagnostic system of this syndrome should be established in Japan to enable us to estimate its frequency and treatment. (C) 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

We report on a 1-year-old boy with microcephaly with a simplified gyral pattern, early-onset seizures, congenital hearing loss and a severe developmental delay. Trio-based whole-exome sequencing identified candidate compound heterozygous mutations in two genes: c.163G > T (p.Ala55Ser) and c.874G > A (p.Gly292Arg) in polynucleotide kinase 30-phosphatase gene (PNKP), and c.195G > A (p.Met65Ile) and c.1210A > C (p.Ser404Arg) in PCDH15. PNKP and PCDH15 mutations have been reported in autosomal recessive microcephaly with early-onset seizures and developmental delay syndrome, and Usher syndrome type 1F, respectively. Our patient showed neurological features similar to reported cases of both syndromes that could be explained by the observed mutations in both PNKP and PCDH15, which therefore appear to be pathogenic in this case.

Objective:We performed whole-exome sequencing analysis of patients with genetically unsolved hypomyelinating leukoencephalopathies, identifying 8 patients with TUBB4A mutations and allowing the phenotypic spectrum of TUBB4A mutations to be investigated.Methods:Fourteen patients with hypomyelinating leukoencephalopathies, 7 clinically diagnosed with hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC), and 7 with unclassified hypomyelinating leukoencephalopathy, were analyzed by whole-exome sequencing. The effect of the mutations on microtubule assembly was examined by mapping altered amino acids onto 3-dimensional models of the -tubulin heterodimer.Results:Six heterozygous missense mutations in TUBB4A, 5 of which are novel, were identified in 8 patients (6/7 patients with H-ABC [the remaining patient is an atypical case] and 2/7 patients with unclassified hypomyelinating leukoencephalopathy). In 4 cases with parental samples available, the mutations occurred de novo. Analysis of 3-dimensional models revealed that the p.Glu410Lys mutation, identified in patients with unclassified hypomyelinating leukoencephalopathy, directly impairs motor protein and/or microtubule-associated protein interactions with microtubules, whereas the other mutations affect longitudinal interactions for maintaining -tubulin structure, suggesting different mechanisms in tubulin function impairment. In patients with the p.Glu410Lys mutation, basal ganglia atrophy was unobserved or minimal although extrapyramidal features were detected, suggesting its functional impairment.Conclusions:TUBB4A mutations cause typical H-ABC. Furthermore, TUBB4A mutations associate cases of unclassified hypomyelinating leukoencephalopathies with morphologically retained but functionally impaired basal ganglia, suggesting that TUBB4A-related hypomyelinating leukoencephalopathies encompass a broader clinical spectrum than previously expected. Extrapyramidal findings may be a key for consideration of TUBB4A mutations in hypomyelinating leukoencephalopathies.

Knowledge of MRI findings in pediatric cerebral infarction is limited. To determine whether cortical necrosis and network injury appear in the acute phase in post-stroke children and to identify anatomical location of acute network injury and the ages at which these phenomena are seen. Images from 12 children (age range: 0-9 years; neonates [< 1 month], n=5; infants [1 month-12 months], n=3; others [a parts per thousand yen1 year], n=4) with acute middle cerebral artery (MCA) cortical infarction were retrospectively analyzed. Cortical necrosis was defined as hyperintense cortical lesions on T1-weighted imaging that lacked evidence of hemorrhage. Acute network injury was defined as hyperintense lesions on diffusion-weighted imaging that were not in the MCA territory and had fiber connections with the affected cerebral cortex. MRI was performed within the first week after disease onset. Cortical necrosis was only found in three neonates. Acute network injury was seen in the corticospinal tract (CST), thalamus and corpus callosum. Acute network injury along the CST was found in five neonates and one 7-month-old infant. Acute network injury was evident in the thalamus of four neonates and two infants (ages 4 and 7 months) and in the corpus callosum of five neonates and two infants (ages 4 and 7 months). The entire thalamus was involved in three children when infarction of MCA was complete. In acute MCA cortical infarction, MRI findings indicating cortical necrosis or acute network injury was frequently found in neonates and early infants. Response to injury in a developing brain may be faster than that in a mature one.

Objective:To investigate the clinical spectrum caused by mutations in PIGA at Xp22.2, which is involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor, among patients with early-onset epileptic encephalopathies (EOEEs).Methods:Whole-exome sequencing was performed as a comprehensive genetic analysis for a cohort of 172 patients with EOEEs including early myoclonic encephalopathy, Ohtahara syndrome, and West syndrome, and PIGA mutations were carefully investigated.Results:We identified 4 PIGA mutations in probands showing early myoclonic encephalopathy, West syndrome, or unclassified EOEE. Flow cytometry of blood granulocytes from patients demonstrated reduced expression of GPI-anchored proteins. Expression of GPI-anchored proteins in PIGA-deficient JY5 cells was only partially or hardly restored by transient expression of PIGA mutants with a weak TATA box promoter, indicating a variable loss of PIGA activity. The phenotypic consequences of PIGA mutations can be classified into 2 types, severe and less severe, which correlate with the degree of PIGA activity reduction caused by the mutations. Severe forms involved myoclonus and asymmetrical suppression bursts on EEG, multiple anomalies with a dysmorphic face, and delayed myelination with restricted diffusion patterns in specific areas. The less severe form presented with intellectual disability and treatable seizures without facial dysmorphism.Conclusions:Our study confirmed that PIGA mutations are one genetic cause of EOEE, suggesting that GPI-anchor deficiencies may be an underlying cause of EOEE.

Pelizaeus-Merzbacher disease (PMD) is a form of X-linked leukodystrophy caused by mutations in the proteolipid protein 1 (PLP1) gene. Although PLP1 proteins with missense mutations have been shown to accumulate in the rough endoplasmic reticulum (ER) in disease model animals and cell lines transfected with mutant PLP1 genes, the exact pathogenetic mechanism of PMD has not previously been clarified. In this study, we established induced pluripotent stem cells (iPSCs) from two PMD patients carrying missense mutation and differentiated them into oligodendrocytes in vitro. In the PMD iPSC-derived oligodendrocytes, mislocalization of mutant PLP1 proteins to the ER and an association between increased susceptibility to ER stress and increased numbers of apoptotic oligodendrocytes were observed. Moreover, electron microscopic analysis demonstrated drastically reduced myelin formation accompanied by abnormal ER morphology. Thus, this study demonstrates the involvement of ER stress in pathogenic dysmyelination in the oligodendrocytes of PMD patients with the PLP1 missense mutation.

To determine the epidemiological, clinical, and genetic characteristics of congenital hypomyelinating leukodystrophies, including Pelizaeus-Merzbacher disease (PMD), we conducted a nationwide epidemiological survey in Japan. A two-step survey targeting all medical institutions specializing in pediatric neurology and childhood disability (919 institutes) in Japan was performed. Detailed information was collected for 101 patients (86 males and 15 females) with congenital hypomyelinating leukodystrophies. The prevalence of congenital hypomyelinating disorders was 0.78 per 100,000 people (0-19 years old), and the incidence was 1.40 per 100,000 live births. Molecular testing was performed in 75 % of patients, and PLP1 gene abnormalities were observed in 62 %. The incidence of PMD with PLP1 mutations was estimated to be 1.45 per 100,000 male live births and that for congenital hypomyelinating disorders with unknown cause to be 0.41 per 100,000 live births. Patients with PLP1 mutations showed a higher proportion of nystagmus and hypotonia, both of which tend to disappear over time. Our results constitute the first nationwide survey of congenital hypomyelinating disorders, and provide the epidemiological, clinical, and genetic landscapes of these disorders.

BACKGROUND: Determining the relationship between clinical phenotype and genotype in genetic diseases is important in clinical practice. In general, frameshift mutations are expected to produce premature termination codons, leading to production of mutant transcripts destined for degradation by nonsense-mediated decay. In X-linked recessive diseases, male patients with frameshift mutations typically have a severe or even lethal phenotype. PATIENT: We report a case of a 17-month-old boy with Menkes disease (NIM #309400), an X-linked recessive copper metabolism disorder caused by mutations in the ATP7A copper transporter gene. He exhibited an unexpectedly late onset and experienced milder symptoms. STUDY AND RESULT: His genomic DNA showed a de novo two-nucleotide deletion in exon 4 of ATP7A, predicting a translational frameshift and premature stop codon, and a classic severe phenotype. Characterization of his ATP7A mRNA showed no abnormal splicing. CONCLUSION: We speculate that translation reinitiation could occur downstream to the premature termination codon and produce a partially functional ATP7A protein. Study of the child's fibroblasts found no evidence of translation reinitiation; however, the possibility remains that this phenomenon occurred in neural tissues and influenced the clinical phenotype.

Background: Mutations of POLR3A and POLR3B have been reported to cause several allelic hypomyelinating disorders, including hypomyelination with hypogonadotropic hypogonadism and hypodontia (4H syndrome). Patients and methods: To clarify the difference in MRI between the two genotypes, we reviewed MRI in three patients with POLR3B mutations, and three with POLR3A mutations. Results: Though small cerebellar hemispheres and vermis are common MRI findings with both types of mutations, MRI in patients with POLR3B mutations revealed smaller cerebellar structures, especially vermis, than those in POLR3A mutations. MRI also showed milder hypomyelination in patients with POLR3B mutations than those with POLR3A mutations, which might explain milder clinical manifestations. Conclusions: MRI findings are distinct between patients with POLR3A and 3B mutations, and can provide important clues for the diagnosis, as these patients sometimes have no clinical symptoms suggesting 4H syndrome. (C) 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Leigh syndrome (LS) is an early-onset progressive neurodegenerative disorder characterized by unique, bilateral neuropathological findings in brainstem, basal ganglia, cerebellum and spinal cord. LS is genetically heterogeneous, with the majority of the causative genes affecting mitochondrial malfunction, and many cases still remain unsolved. Here, we report male sibs affected with LS showing ketonemia, but no marked elevation of lactate and pyruvate. To identify their genetic cause, we performed whole exome sequencing. Candidate variants were narrowed down based on autosomal recessive and X-linked recessive models. Only one hemizygous missense mutation (c.665G > C, p.W222S) in glycogenin-2 (GYG2) (isoform a: NM_001079855) in both affected sibs and a heterozygous change in their mother were identified, being consistent with the X-linked recessive trait. GYG2 encodes glycogenin-2 (GYG2) protein, which plays an important role in the initiation of glycogen synthesis. Based on the structural modeling, the mutation can destabilize the structure and result in protein malfunctioning. Furthermore, in vitro experiments showed mutant GYG2 was unable to undergo the self-glucosylation, which is observed in wild-type GYG2. This is the first report of GYG2 mutation in human, implying a possible link between GYG2 abnormality and LS.

Aberrations in the glycosylphosphatidylinositol (GPI)-anchor biosynthesis pathway constitute a subclass of congenital disorders of glycosylation, and mutations in seven genes involved in this pathway have been identified. Among them, mutations in PIGV and PIGO, which are involved in the late stages of GPI-anchor synthesis, and PGAP2, which is involved in fatty-acid GPI-anchor remodeling, are all causative for hyperphosphatasia with mental retardation syndrome (HPMRS). Using whole exome sequencing, we identified novel compound heterozygous PIGO mutations (c.389C>A [p.Thr130Asn] and c.1288C>T [p.Gln430*]) in two siblings, one of them having epileptic encephalopathy. GPI-anchored proteins (CD16 and CD24) on blood granulocytes were slightly decreased compared with a control and his mother. Our patients lacked the characteristic features of HPMRS, such as facial dysmorphology (showing only a tented mouth) and hypoplasia of distal phalanges, and had only a mild elevation of serum alkaline phosphatase (ALP). Our findings therefore expand the clinical spectrum of GPI-anchor deficiencies involving PIGO mutations to include epileptic encephalopathy with mild elevation of ALP.

Purpose: To evaluate the efficacy and safety of stiripentol as add-on therapy in Japanese patients with Dravet syndrome treated with clobazam (CLB) and valproate (VPA). Methods: In this open-label study, patients aged 1-30 years entered a 4-week baseline phase, followed by a 4-week stiripentol dose-adjustment and 12-week fixed-dose phase. The primary efficacy endpoint was responder rate (proportion of patients with a ≥50% reduction from baseline phase in clonic or tonic-clonic seizure frequency over the last 4 weeks of fixed-dose treatment [target phase]). Safety and pharmacokinetics were also assessed. Key findings: Of 27 patients screened in the baseline phase, 24 patients entered the dose-adjustment phase. All patients completed the study. Responder rate was 66.7% (16/24, 95% CI: 44.7-84.4%), and four patients became free from clonic or tonic-clonic seizures. The duration of clonic or tonic-clonic seizures was also significantly reduced in the target versus baseline phase. The most frequent adverse events were somnolence, anorexia, ataxia, nasopharyngitis and γ-glutamyl transpeptidase increase, all of which were of mild-to-moderate severity. Stiripentol plasma concentration in the fixed-dose phase was 4-25. μg/mL. After adding stiripentol to CLB and VPA, the minimum plasma concentrations of CLB and N-desmethyl-CLB (NCLB) increased and that of 4'-hydroxy-N-desmethyl-CLB(OH-NCLB) decreased, while those of VPA and bromide (optionally used) were not affected. Significance: Add-on stiripentol to CLB and VPA was well tolerated and significantly decreased clonic or tonic-clonic seizures in patients with Dravet syndrome. © 2014 Elsevier B.V.

Large numbers of genes are responsible for Leigh syndrome (LS), making genetic confirmation of LS difficult. We screened our patients with LS using a limited set of 21 primers encompassing the frequently reported gene for the respiratory chain complexes I (ND1-ND6, and ND4L), IV(SURF1), and V(ATP6) and the pyruvate dehydrogenase E1α-subunit. Of 18 LS patients, we identified mutations in 11 patients, including 7 in mDNA (two with ATP6), 4 in nuclear (three with SURF1). Overall, we identified mutations in 61% of LS patients (11/18 individuals) in this cohort. Sanger sequencing with our limited set of primers allowed us a rapid genetic confirmation of more than half of the LS patients and it appears to be efficient as a primary genetic screening in this cohort. © 2014 The Authors. Published by Elsevier Inc.

INTRODUCTION: Glucose transporter type 1 deficiency syndrome is a metabolic encephalopathy that results from impaired glucose transport into the brain as the result of a mutation of the SLC2A1 gene. It has been recognized recently that these patients can present with a much broader clinical spectrum than previously thought. We describe a 3-year-old boy presenting with episodic ataxia. CASE REPORT: Our patient exhibited periodic abnormal eye movements, including opsoclonus, since he was 4 months of age. At 2 years of age, he experienced acute cerebellar ataxia after a vaccination. Since then, he has had periodic attacks of ataxic gait, repeated vomiting, and abnormal eye movement. He was diagnosed as having episodic ataxia type 2 because the administration of acetazolamide seemed effective. By 3 years and 10 months of age, he exhibited mild mental retardation and mild trunk ataxia. The attacks were more likely to occur when he was hungry. Molecular analysis revealed that the SLC2A1 gene had a de novo mutation of heterozygous seven nucleotide insertion within exon 7, resulting in a frameshift. He has recently begun a modified Atkins diet; the frequency of attacks has been reduced, and his psychomotor and language skills have begun to develop. DISCUSSION: Glucose transporter type 1 deficiency syndrome should be considered in the differential diagnosis in children with episodic ataxia, even if acetazolamide is effective.

A 35-year-old woman was admitted with subacute intellectual deterioration. Laboratory studies showed elevated total homocysteine and decreased folic acid. MRI revealed leukoencephalopathy with a posterior predominance, and hyperintensity in the pyramidal tracts on T2-weighted and FLAIR images. The enzyme assay showed a deficiency of methylenetetrahydrofolate reductase (MTHFR) activity with low residual activity of 4.2% of the mean control value in cultured fibroblasts. Sequence analysis of the MTHFR gene demonstrated two homozygous missense mutations, c.677C&gt T (p.Ala222Val) and c.685A&gt C (p.Ile225Leu). c.677C&gt T (p.Ala222Val) is known as a common polymorphism and c.685A&gt C (p.Ile225Leu) is considered to be a novel polymorphism. A diagnosis of MTHFR deficiency was made. Treatment with folic acid, vitamin B12 and B6 made significant improvement of intellectual deterioration and reduction in the total homocysteine level. They also made marked resolution of leukoencephalopathy. Posterior-predominant leukoencephalopathy was found to be an excellent marker of MTHFR deficiency, and may help to establish the diagnosis.

BACKGROUND: Proteolipid protein 1 gene (PLP1) mutations result in a continuum of neurological findings characterized by X-linked hypomyelinating leukodystrophies of the central nervous system, from mild spastic paraplegia type 2 to severe Pelizaeus Merzbacher disease. PATIENTS: We report spastic paraplegia type 2 in three individuals in one family. A 29-year-old man developed progressive spastic quadriplegia from early childhood with dysarthria, ataxia, dysphagia, and intellectual delay, but he displayed no nystagmus. His mother developed adult-onset mild spastic diplegia with dementia developing in later life, whereas his sister exhibited spastic diplegia from childhood, complicated by motor developmental delay and dysphagia. All three individuals had initially mild but progressive neurological phenotypes, no nystagmus, normal brainstem auditory-evoked potentials, and demyelinating peripheral neuropathy, but with varying clinical severity. RESULTS: A 33-kb deletion encompassing exon 2 to 7 of PLP1 was identified in all three patients. Cloning of the junction fragment of the genomic recombination revealed a short palindromic sequence at the distal breakpoint, potentially facilitating a double-strand deoxyribonucleic acid break, followed by nonhomologous end joining. X-inactivation study and sequencing of the undeleted PLP1 alleles failed to explain the differences in severity between the two female patients. CONCLUSIONS: PLP1 partial deletion is a rare cause of spastic paraplegia type 2 and exhibits X-linked dominant inheritance with variable expressivity.

Early-onset epileptic encephalopathies (EOEE) are severe neurological disorders characterized by frequent seizures accompanied by developmental regression or retardation. Whole-exome sequencing of 12 patients together with five pairs of parents and subsequent Sanger sequencing in additional 328 EOEE patients identified two de novo frameshift and one missense mutations in SLC35A2 at Xp11.23, respectively. The three patients are all females. X-inactivation analysis of blood leukocyte DNA and mRNA analysis using lymphoblastoid cells derived from two patients with a frameshift mutation indicated that only the wild-type SLC35A2 allele was expressed in these cell types, at least in part likely as a consequence of skewed X-inactivation. SLC35A2 encodes a UDP-galactose transporter (UGT), which selectively supplies UDP-galactose from the cytosol to the Golgi lumen. Transient expression experiments revealed that the missense mutant protein was correctly localized in the Golgi apparatus. In contrast, the two frameshift mutant proteins were not properly expressed, suggesting that their function is severely impaired. Defects in the UGT can cause congenital disorders of glycosylation. Of note, no abnormalities of glycosylation were observed in three serum glycoproteins, which is consistent with favorably skewed X-inactivation. We hypothesize that a substantial number of neurons might express the mutant SLC35A2 allele and suffer from defective galactosylation, resulting in EOEE. (C) 2013 Wiley Periodicals, Inc.

Cerebellar and/or vermis atrophy is recognized in various types of childhood disorders with clinical and genetic heterogeneity. Although careful evaluation of clinical features and neuroimaging can lead to correct diagnosis of disorders, their diagnosis is sometimes difficult because clinical features can overlap with each other. In this study, we performed family-based whole exome sequencing of 23 families including 25 patients with cerebellar and/or vermis atrophy in childhood, who were unable to be diagnosed solely by clinical examination. Pathological mutations of seven genes were found in ten patients from nine families (9/23, 39.1 %): compound heterozygous mutations in FOLR1, C5orf42, POLG, TPP1, PEX16, and de novo mutations in CACNA1A, and ITPR1. Patient 1A with FOLR1 mutations showed extremely low concentration of 5-methyltetrahydrofolate in the cerebrospinal fluid and serum, and Patient 6 with TPP1 mutations demonstrated markedly lowered tripeptidyl peptidase 1 activity in leukocytes. Furthermore, Patient 8 with PEX16 mutations presented a mild increase of very long chain fatty acids in the serum as supportive data for genetic diagnosis. The main clinical features of these ten patients were nonspecific and mixed, and included developmental delay, intellectual disability, ataxia, hypotonia, and epilepsy. Brain MRI revealed both cerebellar and vermis atrophy in eight patients (8/10, 80 %), vermis atrophy/hypoplasia in two patients (2/10, 20 %), and brainstem atrophy in one patient (1/10, 10 %). Our data clearly demonstrate the utility of whole exome sequencing for genetic diagnosis of childhood cerebellar and/or vermis atrophy.

A stroke-like episode is a core symptom in mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Proton magnetic resonance spectroscopy (H-1-MRS) is useful in the diagnosis of mitochondrial diseases. We report an 8-year-old girl with MELAS, presenting with a seizure and blindness. H-1-MRS showed a strikingly elevated lactate peak in the right occipital region, where no abnormal signals appeared on either T2-W or diffusion-weighted MRI. She recovered completely within a day. We describe this mild clinical condition with abnormal lactate peak in normal-appearing gray matter as a transient ischemic attack-like episode in MELAS.

Objective: We aimed to investigate the possible association between SCN2A mutations and early-onset epileptic encephalopathies (EOEEs). Methods: We recruited a total of 328 patients with EOEE, including 67 patients with Ohtahara syndrome (OS) and 150 with West syndrome. SCN2A mutations were examined using high resolution melt analysis or whole exome sequencing. Results: We found 14 novel SCN2A missense mutations in 15 patients: 9 of 67 OS cases (13.4%), 1 of 150 West syndrome cases (0.67%), and 5 of 111 with unclassified EOEEs (4.5%). Twelve of the 14 mutations were confirmed as de novo, and all mutations were absent in 212 control exomes. A de novo mosaic mutation (c.3976G>C) with a mutant allele frequency of 18% was detected in one patient. One mutation (c.634A>G) was found in transcript variant 3, which is a neonatal isoform. All 9 mutations in patients with OS were located in linker regions between 2 transmembrane segments. In 7 of the 9 patients with OS, EEG findings transitioned from suppression-burst pattern to hypsarrhythmia. All 15 of the patients with novel SCN2A missense mutations had intractable seizures; 3 of them were seizure-free at the last medical examination. All patients showed severe developmental delay. Conclusions: Our study confirmed that SCN2A mutations are an important genetic cause of OS. Given the wide clinical spectrum associated with SCN2A mutations, genetic testing for SCN2A should be considered for children with different epileptic conditions.

In this study, we report the case of an 8-year-old girl who had three episodes of reversible splenial lesion of the corpus callosum (SCC) in 2 years. Vomiting, hypoglycemia, and fever were followed by altered consciousness and diminished muscle tone. In each episode, the clinical manifestations and abnormalities detected during magnetic resonance imaging resolved in 2 weeks. Transient alteration of vision and spike discharges revealed by interictal electroencephalogram implied the SCC lesions were related to epileptic activities. At follow-up, the patient had not presented with SCC lesions or altered consciousness for more than 4 years after undergoing carbamazepine treatment. Our case is the first report of a patient who presented with three episodes of reversible splenial lesion.

Nemaline myopathy (NEM) is a common congenital myopathy. At the very severe end of the NEM clinical spectrum are genetically unresolved cases of autosomal-recessive fetal akinesia sequence. We studied a multinational cohort of 143 severe-NEM-affected families lacking genetic diagnosis. We performed whole-exome sequencing of six families and targeted gene sequencing of additional families. We identified 19 mutations in KLHL40 (kelch-like family member 40) in 28 apparently unrelated NEM kindreds of various ethnicities. Accounting for up to 28% of the tested individuals in the Japanese cohort, KLHL40 mutations were found to be the most common cause of this severe form of NEM. Clinical features of affected individuals were severe and distinctive and included fetal akinesia or hypokinesia and contractures, fractures, respiratory failure, and swallowing difficulties at birth. Molecular modeling suggested that the missense substitutions would destabilize the protein. Protein studies showed that KLHL40 is a striated-muscle-specific protein that is absent in KLHL40-associated NEM skeletal muscle. In zebrafish, klhl40a and klhl40b expression is largely confined to the myotome and skeletal muscle, and knockdown of these isoforms results in disruption of muscle structure and loss of movement. We identified KLHL40 mutations as a frequent cause of severe autosomal-recessive NEM and showed that it plays a key role in muscle development and function. Screening of KLHL40 should be a priority in individuals who are affected by autosomal-recessive NEM and who present with prenatal symptoms and/or contractures and in all Japanese individuals with severe NEM.