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Objective: This study aimed to investigate the clinical characteristics of pediatric-onset dystonia in Japan, addressing the diagnostic challenges arising from symptom variations and etiological diversity., Methods: From 2020 to 2022, questionnaires were distributed to 1218 board certified child neurologists (BCCNs) by Japanese Society of Child Neurology. In the primary survey, participants were asked to report the number of patients with pediatric-onset dystonia under their care. Subsequently, the follow-up secondary survey sought additional information on the clinical characteristics of these patients., Results: The primary survey obtained 550 responses (response rate: 45 %) from BCCNs for their 736 patients with dystonia. The predominant etiologies included inherited cases (with DYT10   being the most prevalent, followed by DYT5 and ATP1A3-related neurologic disorders), acquired cases (with perinatal abnormalities being the most common), and idiopathic cases. The secondary survey provided clinical insights into 308 cases from 82 BCCNs. Infancy-onset dystonia presented as persistent and generalized with diverse symptoms, primarily linked to ATP1A3-related neurologic disorders and other genetic disorders resembling acquired dystonia. Conversely, childhood/adolescent-onset dystonia showed paroxysmal, fluctuating courses, predominantly affecting limbs. The most common etiologies were DYT5 and DYT10 , leading to therapeutic diagnoses., Conclusion: Pediatric-onset dystonia in Japan was treated by 28 % of BCCNs. The majority of cases were inherited, with high prevalence rates of DYT5 and DYT10 . Infancy-onset dystonia exhibits diverse etiologies and symptoms, emphasizing the utility of various examinations, including genetic testing. These findings significantly contribute to our understanding of pediatric-onset dystonia in Japan, although this study has the limitation of questionnaire survey., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: ST3GAL5 encodes GM3 synthase (ST3 beta-galactoside alpha-2,3-sialyltransferase 5; ST3GAL5), which synthesizes GM3 by transferring sialic acid to lactosylceramide. GM3, a sialic acid-containing glycosphingolipid known as ganglioside, is a precursor to the biosynthesis of various more complex gangliosides that are active in the brain. Biallelic variants in ST3GAL5 cause GM3 synthase deficiency (GM3SD), a rare congenital disorder of glycosylation. GM3SD was first identified in the Amish population in 2004., Case: We report two siblings diagnosed with GM3SD due to novel compound heterozygous ST3GAL5 variants. The novel ST3GAL5 variants, detected by whole-exome sequencing in the patients, were confirmed to be pathogenic by GM3 synthase assay. The clinical courses of these patients, which began in infancy with irritability and growth failure, followed by developmental delay and hearing loss, were consistent with previous case reports of GM3SD. The older sibling underwent deep brain stimulation for severe involuntary movements at the age of 9 years. The younger sibling suffered from acute encephalopathy at the age of 9 months and subsequently developed refractory epilepsy., Discussion: Reports of GM3SD outside the Amish population are rare, and whole-exome sequencing may be required to diagnose GM3SD in non-Amish patients. Since an effective treatment for GM3SD has not yet been established, we might select deep brain stimulation as a symptomatic treatment for involuntary movements in GM3SD., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Real-world data have shown variability in treatment responses to nusinersen in spinal muscular atrophy (SMA). We investigated whether the magnitude of muscle impairment assessed by magnetic resonance imaging (MRI) at baseline can predict the treatment response., Methods: We retrospectively assessed the clinical data in relevance to the thigh and pelvic MRI taken before the nusinersen treatment. A total of 16 patients with SMA types 2 and 3 (age = mean [SD]; 9.2 [4.6] year) receiving nusinersen treatment were enrolled. The T1-weighted MRI images of the pelvis and thigh were scored for muscle fatty infiltration and atrophy. The minimally clinically important difference (MCID) was considered as gaining at least 3 points of Hammersmith Functional Motor Scale-Expanded (HFMSE) from baseline., Results: Of these 16 individuals, 14 had been treated for at least 15 months with baseline data. At 15 months, seven individuals obtained MCID in HFMSE. Baseline muscle MRI score could not differentiate the two groups; however, individuals who obtained MCID had significantly less severe scoliosis. In addition, there was a significant and negative relationship between baseline MRI score and the change of score in HFMSE after 15 months of treatment. Further, baseline Cobb angle along with MRI score also indicated the correlation to the degree of change in motor function., Conclusion: The degree of muscle damage may confer the variability in response to nusinersen in SMA types 2 and 3. Muscle MRI score along with the severity of scoliosis assessed at baseline may help to predict the motor function change., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a progressive neurodegenerative disorder with stroke-like lesions. The common MRI findings are gyral swelling and high signal intensity on T2WI/FLAIR images crossing the vascular territories. We have observed a linear cystic lesion and a laminar necrosis in the affected cortices of MELAS patients. Herein, we evaluated these cortical MRI findings in each subtype of mitochondrial disease., Patients and Methods: We retrospectively reviewed the MRI findings of 71 consecutive patients with clinically and genetically confirmed mitochondrial diseases. The cortical cystic lesions and laminar necrotic lesions were evaluated on T1, T2, and FLAIR images in each subtype of mitochondrial disease, as were their clinical and other imaging characteristics., Results: The cortical cystic lesion was observed in 21 of the 71 patients (29.6%) with mitochondrial diseases. Laminar necrosis was detected in only three patients (4.2%). MELAS was the most frequent subtype with cortical cystic lesions, accounting for 81.0%, and all showed the linear pattern except for one patient whose pattern was beaded-like., Conclusion: A cortical linear cystic lesion was a common MRI finding in our series of patients with mitochondrial disease, especially in those with MELAS, but laminar necrosis was not. These findings can help differentiate MELAS from infarction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Introduction: An alteration in postoperative cognitive function varies according to the patients' background characteristics, such as etiology, focus, and seizure duration. Accurate prediction and assessment of postoperative cognitive function is difficult in each patient. Adaptive behavior could describe the typical performance of daily activities and represents the ability to translate cognitive potential into real-world skills. We examined the relationship between alterations of executive function (EF) and adaptive behavior in school children undergoing surgery for intractable epilepsy., Methodology: We enrolled 31 children with focal resection or corpus callosotomy for intractable epilepsy [mean age at surgery, 12.5 years; 16 boys; mean intellectual quotient, 73.3]. We surveyed answered questionnaires on attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and adaptive behavior using the Vineland Adaptive Behavior Scale, 2nd edition (VABS-II), and performed continuous performance tests (CPTs) on children pre- and postoperatively., Result: ADHD and ASD symptoms improved after epilepsy surgery. The omission error (OE) in the CPT variable improved after epilepsy surgery, especially in children with a shorter preoperative period. Improved ASD symptoms led to an increased score of the coping skills subdomain. The reduced OE observed after surgery also increased the score of the community skills subdomain., Conclusion: Improvement in EF and ASD symptoms resulted in better adaptive behavior postoperatively. These results were important for the pre- and postoperative evaluation and re-evaluation of children with epilepsy requiring special education and related services., (Copyright © 2020 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Duchenne muscular dystrophy (DMD) is a recessive X-linked genetic disease caused by a mutation in the dystrophin gene. The new drug NS-065/NCNP-01 utilizing exon-skipping therapy targeting specific deletions has been used in a first-in-human trial for the treatment of DMD. We surveyed 10 pairs of DMD participants and their parents within this clinical trial via an iPad survey form and through interviews regarding their understanding of the trial, expectations, anxieties, and reasons for participating in the trial. Approximately half of the participants actively decided to participate of their own volition, and none considered quitting the trial. This indicates that participants participated more positively in this clinical trial than previously expected. However, some potential concerns were also revealed, with one being that the desire to please those around them might be more important to the DMD participants than the effects of the drug. Another issue is the possibility of biased information originating from the study subjects' parents; while seven out of 10 of the parents told their children that the study drug might work, only four of these parents also explained that it might not work. Only two study participants received an explanation concerning the drug's side effects from their parents. This result implies that caution should be taken when family expectations are high, and there is a possibility that subjects will be given biased information from their parents., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: A loss-of-function mutation in CACNA1A, which encodes P/Q-type Ca channels, causes various diseases. As most of the Ca channels at neuromuscular junctions are of the P/Q type, patients with loss-of-function CACNA1A mutations exhibit disturbed neuromuscular transmission. The associated jitters and blocking in such patients can be detected by single-fiber electromyography (SFEMG)., Cases: We report two cases with different phenotypes, which were predicted to harbor loss-of-function mutations of CACNA1A, by using axonal stimulation SFEMG. One case involved a 2-year-old boy with episodic ataxia type 2. The other case involved a 7-year-old girl diagnosed with epileptic encephalopathy. SFEMG results revealed jitters and blocking in both cases. Moreover, whole exome sequencing (WES) revealed a heterozygous CACNA1A mutation, c.5251C>T, p.Arg1751Trp, in the former case and a novel de novo CACNA1A mutation, c.2122G>A, p.Val708Met, in the latter., Conclusions: Our cases indicate that SFEMG is a potentially useful diagnostic tool for patients with CACNA1A mutation, especially in pediatric cases where trio analysis is difficult or novel mutations are present., (Copyright © 2019 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Recently, many genes related to neurodevelopmental disorders have been identified by high-throughput genomic analysis; however, a comprehensive understanding of the mechanism underlying neurodevelopmental disorders remains to be established. To further understand these underlying mechanisms, we performed a comprehensive genomic analysis of patients with undiagnosed neurodevelopmental disorders., Methods: Genomic analysis using next-generation sequencing with a targeted panel was performed for a total of 133 Japanese patients (male/female, 81/52) with previously undiagnosed neurodevelopmental disorders, including developmental delay (DD), intellectual disability (ID), autism spectrum disorder (ASD), and epilepsy. Genomic copy numbers were also analyzed using the eXome Hidden Markov Model (XHMM)., Results: Thirty-nine patients (29.3%) exhibited pathogenic or likely pathogenic findings with single-gene variants or chromosomal aberrations. Among them, 20 patients were presented here. Pathogenic or likely pathogenic variants were identified in 18 genes, including ACTG1, CACNA1A, CHD2, CDKL5, DNMT3A, EHMT1, GABRB3, GABRG2, GRIN2B, KCNQ3, KDM5C, MED13L, SCN2A, SHANK3, SMARCA2, STXBP1, SYNGAP1, and TBL1XR1., Conclusion: A diagnostic yield of 29.3% in this study was nearly the same as that previously reported from other countries. Thus, we suggest that there is no difference in genomic backgrounds in Japanese patients with undiagnosed neurodevelopmental disabilities. Although most of the patients possessed de novo variants, one of the patients showed an X-linked inheritance pattern. As X-linked recessive disorders exhibit the possibility of recurrent occurrence in the family, comprehensive molecular diagnosis is important for genetic counseling., (Copyright © 2019 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Objectives: Quantitative or semiquantitative outcome measures for patients with Duchenne muscular dystrophy (DMD) are important, as they can be objective indicators of the natural history of DMD; these measures also aid in the evaluation of the efficacy of various treatments. However, the most widely used standard outcome measures in patients with DMD, such as the North Star Ambulatory Assessment and the 6-min walk test, cannot be applied after patients have become nonambulatory. We evaluated the utility and reliability of accelerometric analysis of motor activity in nonambulatory patients with DMD., Methods: We measured the motor activity of the upper extremity in 7 nonambulatory patients with DMD, by using an accelerometer attached at the wrist of the dominant arm. To eliminate gravitational acceleration, we measured the changes in acceleration between measurements. The root of the sum of squared values of the changes per unit time in the 3 axes of the accelerometer was defined as a jerk. The total sum of the jerk values obtained at a measurement frequency of 15.625 Hz for 8 h was defined as the cumulative sum of jerks (Cj)., Results: The Cj values had significant and very strong or strong correlations with the Brooke Upper Extremity Scale (r s  = -0.973; p = 0.00023) and the arm function scores for the DMD Functional Ability Self-Assessment Tool (r s  = 0.810, p = 0.027). The values also had a very strong or strong correlation with the elbow flexion strength (nondominant arm: r = 0.931, p = 0.002; dominant arm: r = 0.750, p = 0.052)., Conclusion: Cj assessment is a useful method to evaluate motor activities in nonambulatory patients with DMD., (Copyright © 2019 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Patients with Duchenne muscular dystrophy (DMD) exhibit increased prostaglandin D 2 (PGD 2 ) expression in necrotic muscle and increased PGD 2 metabolites in their urine. In mouse models, inhibiting PGD 2 production suppresses muscle necrosis, suggesting a possible intervention through PGD 2 -mediated activities., Objective: We investigated the involvement of PGD 2 and its potential use as a marker of pathological progression in DMD., Methods: Sixty-one male children with DMD and thirty-five age-matched controls were enrolled in the study. DMD patients were divided into "ambulant" and "non-ambulant" groups, which were further subdivided into "steroid" and "non-steroid" therapy groups. Levels of the PGD 2 metabolite tetranor-PGDM (t-PGDM) and creatinine were measured in both spot and 24-hour urine samples, with comparisons between groups made according to geometric mean values., Results: DMD patients had significantly higher levels of creatinine-corrected t-PGDM in spot urine samples as compared with the control group. Additionally, both ambulant and non-ambulant DMD groups had significantly higher levels of t-PGDM as compared with controls, with no significant difference in t-PGDM levels observed between steroid and non-steroid groups. Moreover, total creatinine excretion in 24-hour urine samples was significantly lower in DMD patients as compared with controls, and although DMD patients had lower muscle mass than controls, their overall levels of t-PGDM did not differ significantly from those in the non-ambulant and control groups., Conclusion: PGD 2 might help explain the progression and symptomatic presentations (e.g., ambulatory difficulty) associated with DMD, suggesting it as a useful pathological marker and use of a selective PGD 2 inhibitor as a potential treatment modality., (Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Diagnosis of Pompe disease is sometimes challenging because it exhibits clinical similarities to muscular dystrophy., Case: We describe a case of Becker muscular dystrophy (BMD) with a remarkable reduction in activity of the acid α-glucosidase (GAA) enzyme, caused by a combination of pathogenic mutation and polymorphism variants resulting in pseudodeficiency in GAA. The three-year-old boy demonstrated asymptomatic creatine kinase elevation. Neither exon deletion nor duplication was detected on multiplex ligation-dependent probe amplification (MLPA) of DMD. GAA enzyme activity in both dried blood spots and lymphocytes was low, at 11.7% and 7.7% of normal, respectively. However, genetic analysis of GAA detected only heterozygosity for a nonsense mutation (c.118C > T, p.Arg40 ∗ ). Muscle pathology showed no glycogen deposits and no high acid phosphatase activity. Hematoxylin-eosin staining detected scattered regenerating fibers; the fibers were faint and patchy on immunochemistry staining of dystrophin. The amount of dystrophin protein was reduced to 11.8% of normal, on Western blotting analysis. Direct sequencing analysis of DMD revealed hemizygosity for a nonsense mutation (c.72G > A, p.Trp24 ∗ ). The boy was diagnosed with BMD, despite remarkable reduction in GAA activity; further, he demonstrated heterozygosity for [p.Gly576Ser; p.Glu689Lys] polymorphism variants that indicated pseudodeficiency on another allele in GAA., Conclusions: Pseudodeficiency alleles are detected in approximately 4% of the Asian population; these demonstrate low activity of acid α-glucosidase (GAA), similar to levels found in Pompe disease. Clinicians should be careful in their interpretations of pseudodeficiency alleles that complicate diagnosis in cases of elevated creatine kinase., (Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

A heterozygous mutation in the fibroblast growth factor 12 (FGF12) gene, which elevates the voltage dependence of neuronal sodium channel fast inactivation, was recently identified in some patients with epileptic encephalopathy. Here we report 1 Japanese patient diagnosed with early infantile epileptic encephalopathy (EIEE) and another diagnosed with epilepsy of infancy with migrating focal seizures (EIMFS). These 2 patients had an identical heterozygous missense mutation [c.341G>A:p.(Arg114His)] in FGF12 , which was identified with whole-exome sequencing. This mutation is identical to previously reported mutations in cases with early onset epileptic encephalopathy. One of our cases exhibited EIMFS, and this case responded to phenytoin and high-dose phenobarbital (PB). FGF12-related epileptic encephalopathy may exhibit diverse phenotypes and may respond to sodium channel blockers or high-dose PB., (Copyright © 2018. Published by Elsevier B.V.)

Introduction: Chilaiditi syndrome is a rare pathophysiology in which the colon or other organs are interposed between the diaphragm and liver, and respiratory or digestive symptoms sometimes manifest. Although there have been some cases of Chilaiditi syndrome complicating neuromuscular disorders, none have described resulting respiratory or digestive symptoms., Case Presentation: Our patient was a 20-year-old man with DMD who had been receiving noninvasive positive-pressure ventilation during the night. He experienced respiratory distress when changing from a supine to sitting position. Ventilator adjustment did not relieve the respiratory distress. Abdominal computed tomography revealed marked constipation and interposition of the transverse colon between the diaphragm and liver, indicating Chilaiditi syndrome. The right side of the diaphragm was elevated by the interposed transverse colon when the respiratory distress was present on chest radiograph, but not when symptoms were absent. The patient was diagnosed with platypnea-orthodeoxia attributed to Chilaiditi syndrome. The respiratory distress was improved by the relief of constipation, in addition to the usage of the ventilator throughout the day., Conclusion: The rare symptoms and pathophysiology of DMD complicated by Chilaiditi syndrome are reported and discussed herein., (Copyright © 2017 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Introduction: Corticosteroids are effective for improving motor function in patients with Duchenne muscular dystrophy (DMD), but there is no consensus on a regimen that balances efficacy and side effects., Methods: Data from three groups of DMD patients were retrospectively analyzed: those treated with 0.75mg/kg/day prednisolone every day (daily group, n=51); those treated with 1mg/kg/day prednisolone on alternate days (intermittent group, n=36), and those not treated with steroids (nontreatment group, n=42)., Results: Although the age of ambulation loss did not differ significantly among the groups, the hazard ratios for ambulation loss relative to the nontreatment group were 0.24 (95% confidence interval [CI]: 0.11-0.54) in the daily group and 0.34 (95% CI: 0.19-0.62) in the intermittent group. The percentage of predicted forced vital capacity increased until 9.6years of age (to 94.1%) in the daily group, until 8.8years of age (to 96.9%) in the intermittent group, and until 7.2years of age (to 87.6%) in the nontreatment group. Weight gain was the most frequently observed side effect in the treated groups. Height was significantly lower in the daily than in the nontreatment group. Other side effects were observed, but no patient discontinued therapy. There were no marked differences in benefits and side effects between the two treated groups., Discussion: This is the first assessment of long-term outcomes of different steroid therapy regimens in Japanese DMD patients. Benefits and side effects, except height, did not differ significantly between steroid regimens., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Aim: The aim of the study was to understand the long-term health issues and potential predictors of cardiopulmonary arrest (CPA) in patients with severe childhood-onset psychomotor impairments., Method: In this single-center, retrospective observational study, the medical records of 140 patients with severe childhood-onset psychomotor impairments were reviewed. The medical interventions and functional status of patients with a history of CPA (n=22: 14 M/8 F; mean±SD age: 26.6±12.4 years) were compared with age- and sex-matched patients without a history of CPA (n=44: 28 M/16 F; mean±SD age: 26.5±12.3 years)., Results: The prevalence of CPA was 15.7%. The most frequent cause was respiratory issues, and CPA occurred most frequently between 0 and 5 years old. The patients who had a history of CPA were more likely to have required a feeding tube (p=0.0007), tracheostomy (p<0.0001), and ventilator (p=0.002) compared to the non-CPA patients, while the prevalence of tracheostomy or ventilator treatment during early infancy was comparable between both groups. Although statistically non-significant, patients who used antiepileptics or feeding tubes during the neonatal period had higher odds of a future CPA., Interpretation: This single-center study indicated that the prevalence of CPA could be high among individuals with severe childhood-onset psychomotor impairments, and patients who experience CPA have more health issues. The potential predictors for a future CPA are young age (0-5 years), respiratory issues, and antiepileptic or feeding tube usage during the neonatal period. These patients may require extra attention in medical managements., (Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Objective: Neurological manifestations including psychomotor developmental delay and epilepsy in patients with Angelman syndrome caused by ubiquitin protein ligase E3A (UBE3A) mutations has been considered similar but is relatively milder than that in patients with deletion-type Angelman syndrome. This makes the diagnosis of the former subgroup often difficult. We here characterized epilepsy, specifically the types of tremulous movement, in 4 patients (age, 3-38years) with Angelman syndrome caused by UBE3A mutations., Methods: Ictal electroencephalography was used to record episodic tremors in all study patients. Jerk-locked averaging was performed using digital electroencephalography and surface electromyogram data from patients who were monitored for 24h., Results: All patients had tremors in the limbs, head, and trunk, which resulted in 2 patients falling backward. These tremors lasted several seconds, and could emerge in clusters for hours in older patients. In addition, the tremors coincided with 7-8Hz rhythmic activity with a frontocentral predominance, diffuse spike-wave bursts, or no apparent change on electroencephalography. In 2 patients, these tremors were confirmed as cortical myoclonus using jerk-locked averaging. The other seizure types were isolated generalized myoclonus and tonic seizures. None of the patients experienced atypical absence seizures. Levetiracetam therapy was effective in controlling the myoclonic events in 2 of the 3 patients., Conclusion: Semirhythmic myoclonus is common in patients with Angelman syndrome caused by UBE3A mutations, and such myoclonic events are often life disabling. The preserved expression of gamma-aminobutyric acid type A receptor subunit genes located proximal to UBE3A might explain the low prevalence of absence seizures in this population., (Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Aim: To describe the characteristics of hypophosphatemia in severely disabled individuals with neurological disorders and to identify its causative factors., Method: We retrospectively reviewed clinical data from 82 individuals with motor skills classified as sitting, rollover or bedridden. Age, gender and body mass index were compared in individuals with (n=19) and without (n=63) a history of hypophosphatemia (serum phosphate levels <2.0 mg/dl). The clinical course of each patient with hypophosphatemia was reviewed and the cause identified. Laboratory data during hypophosphatemia was compared with that after recovery., Results: The age, gender and body mass index did not differ significantly between the individuals with and without hypophosphatemia. Nineteen patients experienced 25 episodes of hypophosphatemia. The causes included febrile illnesses (n=17), refeeding syndrome (n=4) and Fanconi syndrome (n=3), but was unidentifiable in one episode. Significant elevations in C-reactive protein levels and reductions in sodium levels were observed during hypophosphatemia episodes., Interpretation: Hypophosphatemia is a common complication in severely disabled individuals with frequent bacterial infections, refeeding following malnutrition and valproate administration for epilepsy treatment. Because severe hypophosphatemia is life threatening, serum phosphate levels should be closely monitored in this population., (Copyright © 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Angiotensin II type-2 receptor gene (AGTR2) mutations have been recently detected in patients with mental retardation. AGTR2 plays a role in central nervous system development and cognitive functions. We identified a novel missense mutation of c.572G>A (p.G191E) in a 6-year-old boy showing severe mental retardation, pervasive developmental disorder, and epilepsy. This is the first report on AGTR2 mutation in a Japanese boy with mental retardation., (Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)