Publications by authors named "Mizue Iai"

35 Publications

Recurrent pulmonary hemorrhage in juvenile patients with KCNT1 mutation.

Pediatr Int 2021 Mar 2;63(3):352-354. Epub 2021 Mar 2.

Department of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

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http://dx.doi.org/10.1111/ped.14427DOI Listing
March 2021

Infection-associated decrease of serum creatine kinase levels in Fukuyama congenital muscular dystrophy.

Brain Dev 2021 Mar 2;43(3):440-447. Epub 2020 Dec 2.

Department of Pediatrics, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.

Background: Marked decreases in serum creatine kinase levels have been noted in Duchenne and Becker muscular dystrophies as rare complications of autoimmune or autoinflammatory diseases.

Subjects And Methods: The influence of systemic inflammation on serum creatine kinase levels was reviewed from the charts of three subjects with Fukuyama congenital muscular dystrophy.

Results: A total of 30 infectious events were identified. Elevated serum C-reactive protein levels coincided with decreased creatine kinase levels on 19 occasions. In one subject, administration of 2 mg/kg/d prednisolone for bronchial asthma resulted in a decrease in creatine kinase level on six other occasions.

Conclusion: Apart from an increase in endogenous cortisol secretion, certain inflammation-related molecules could play a role in mitigating muscle cell damage in Fukuyama congenital muscular dystrophy during febrile infectious episodes. Corticosteroids may be a promising agent for the treatment of muscular symptoms in this disorder.
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http://dx.doi.org/10.1016/j.braindev.2020.11.009DOI Listing
March 2021

De novo CACNA1G variants in developmental delay and early-onset epileptic encephalopathies.

J Neurol Sci 2020 Sep 17;416:117047. Epub 2020 Jul 17.

Department of Neurology and Stroke Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. Electronic address:

Introduction: Variants of CACNA1G, which encodes Ca3.1, have been reported to be associated with various neurological disorders.

Methods: Whole-exome sequencing of genomic DNA from 348 Japanese patients with neurodevelopmental disorders and their parents was conducted, and de novo variants of CACNA1G were extracted. The electrophysiological properties of each mutant channel were investigated by voltage-clamp and current-clamp analyses of HEK293T cells overexpressing these channels.

Results: Two patients diagnosed with Rett syndrome and West syndrome were found to have known pathological CACNA1G mutations reported in cerebellar ataxia cohorts: c.2881G > A, p.Ala961Thr and c.4591A > G, p.Met1531Val, respectively. One patient with Lennox-Gastaut syndrome was revealed to harbor a previously unreported heterozygous variant: c.3817A > T, p.Ile1273Phe. Clinical symptoms of the two patients with known mutations included severe developmental delay without acquisition of the ability to walk independently. The patient with a potentially novel mutation showed developmental delay, intractable seizures, and mild cerebral atrophy on MRI, but the severity of symptoms was milder than in the former two cases. Electrophysiological study using HEK293T cells demonstrated significant changes of T-type Ca currents by p.Ala961Thr and p.Met1531Val SNVs, which were likely to enhance oscillation of membrane potential at low frequencies. In contrast, p.Ile1273Phe showed no significant effects in our electrophysiological evaluations, with its pathogenesis remaining undetermined.

Conclusion: De novo variants of CACNA1G explain some neurodevelopmental disorders. Our study further provides information to understand the genotype-phenotype correlations of patients with CACNA1G mutations.
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http://dx.doi.org/10.1016/j.jns.2020.117047DOI Listing
September 2020

Autopsy Report of a Woman with Infantile Alexander Disease Who Survived 39 Years.

Neuropediatrics 2020 08 6;51(4):298-301. Epub 2020 Mar 6.

Institution for Children with Profound Multiple Disabilities, Kanagawa Children's Medical Center, Yokohama, Japan.

Patients with infantile Alexander disease (AxD) usually do not survive beyond their early teens without life support care because of progressive central hypoventilation. We present the autopsy report of a woman with infantile AxD carrying an R239C mutation in the glial fibrillary acidic protein gene, who survived 39 years. She presented with psychomotor retardation in infancy and regressed after age 5. Brain computed tomography scans showed bilateral low frontal white matter density. She became quadriplegic with bulbar palsy and was intellectually handicapped after a measles infection at age 7. Tube feeding was introduced because of dysphagia at age 15. Noninvasive positive pressure ventilation was required due to central hypoventilation in her early thirties. She died of neurogenic respiratory failure at 39 years. Autopsy findings revealed a markedly atrophic brain (709 g, -6.0 standard deviation), especially in the frontal lobe, cerebellum, and brainstem portions. We found demyelination, gliosis, and cystic lesions throughout the brain, and we saw Rosenthal fibers accumulating in the perivascular spaces. We also identified a variety of abnormalities in other organs such as pancreatic necrosis, completely desquamated epithelium in the lower esophagus and stomach, foreign-body giant cells in the colon submucosa, glomerular sclerosis, and multiple bladder stones. This is the first autopsied case report of a patient with infantile AxD with long survival, who showed not only central nervous system characteristic findings, but also unexpected pathological changes in other organs.
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http://dx.doi.org/10.1055/s-0040-1705172DOI Listing
August 2020

Epilepsy in Christianson syndrome: Two cases of Lennox-Gastaut syndrome and a review of literature.

Epilepsy Behav Rep 2020 5;13:100349. Epub 2019 Dec 5.

Department of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

Christianson syndrome (CS) is an X-linked intellectual disorder caused by mutations in the gene. Clinical features of CS include an inability to speak, truncal ataxia, postnatal microcephaly, hyperkinesis, and epilepsy. Almost all patients with CS develop drug-resistant epilepsy-its most serious complication. We report two cases of CS with drug-resistant epilpesy associated with the Lennox-Gastaut syndrome (LGS). One patient experienced generalized tonic seizures since 9 months of age with cognitive regression, which evolved to include atonic seizures at the age of 7 years. Electroencephalography (EEG) showed generalized slow spike-wave complexes and generalized paroxysmal fast activity. Seizures remained drug-resistant despite multiple anti-seizure drugs. The second patient experienced generalized tonic seizures since the age of 17 months and arrested development. EEG showed generalized slow spike-wave complexes, with frequent atonic seizures since the age of 6 years. Electrical status epilepticus during slow-wave sleep (ESES) developed at the age of 7 years. Our cases illustrate that CS may cause LGS in addition to other developmental and epileptic encephalopathies of the neonatal and infantile period. We suggest that generalized tonic or tonic-clonic seizures and generalized slow spike-wave complexes in interictal EEG be included as potential electroclinical features of epilepsy in CS.
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http://dx.doi.org/10.1016/j.ebr.2019.100349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920258PMC
December 2019

Comprehensive analysis of coding variants highlights genetic complexity in developmental and epileptic encephalopathy.

Nat Commun 2019 06 7;10(1):2506. Epub 2019 Jun 7.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.

Although there are many known Mendelian genes linked to epileptic or developmental and epileptic encephalopathy (EE/DEE), its genetic architecture is not fully explained. Here, we address this incompleteness by analyzing exomes of 743 EE/DEE cases and 2366 controls. We observe that damaging ultra-rare variants (dURVs) unique to an individual are significantly overrepresented in EE/DEE, both in known EE/DEE genes and the other non-EE/DEE genes. Importantly, enrichment of dURVs in non-EE/DEE genes is significant, even in the subset of cases with diagnostic dURVs (P = 0.000215), suggesting oligogenic contribution of non-EE/DEE gene dURVs. Gene-based analysis identifies exome-wide significant (P = 2.04 × 10) enrichment of damaging de novo mutations in NF1, a gene primarily linked to neurofibromatosis, in infantile spasm. Together with accumulating evidence for roles of oligogenic or modifier variants in severe neurodevelopmental disorders, our results highlight genetic complexity in EE/DEE, and indicate that EE/DEE is not an aggregate of simple Mendelian disorders.
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http://dx.doi.org/10.1038/s41467-019-10482-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555845PMC
June 2019

Aggregate formation analysis of GFAP found in one case of Alexander disease.

Brain Dev 2019 Feb 10;41(2):195-200. Epub 2018 Sep 10.

Deptartment of Pediatrics, Jichi Medical School, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan. Electronic address:

Alexander disease (AxD) is a neurodegenerative disease in astrocytes caused by a mutation in the gene encoding glial fibrillary acidic protein, GFAP. We herein present the case of a 12-year-old girl who showed intermittent exotropia at 3 years of age and central precocious puberty at 7 years of age. The periventricular and medulla oblongata showed high signal intensity on T2-weighted magnetic resonance imaging. The patient was diagnosed with AxD after direct sequencing revealing a de novo recurrent mutation, c.1246C>T (p.R416W) in GFAP. The transient expression of GFAP in cells resulted in the significant formation of aggregates, which recapitulated the hallmark of AxD. We firstly utilized In Cell analyzer to prove the tendency of aggregate formation by mutants of GFAP.
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http://dx.doi.org/10.1016/j.braindev.2018.08.009DOI Listing
February 2019

Long-term home non-invasive positive pressure ventilation in children: Results from a single center in Japan.

Brain Dev 2018 Aug 7;40(7):558-565. Epub 2018 Apr 7.

Institution for Children with Profound Multiple Disabilities, Kanagawa Children's Medical Center, Japan; Department of Neurology, Kanagawa Children's Medical Center, Japan.

Background: Non-invasive positive pressure ventilation (NPPV) in children has recently increased worldwide and is used not only for neuromuscular diseases but for various other diseases. However, there have been few observational studies on long-term NPPV in children in Japan.

Methods: Based on medical records, we retrospectively evaluated patients aged ≤20 years who were initiated long-term NPPV at our hospital from January 2001 to December 2015.

Results: A total of 53 patients on long-term NPPV were identified; 38 (72%) had severe motor and intellectual disabilities (SMID). Compared to those with non-neuromuscular diseases, those with neuromuscular diseases had significantly more planned initiations and less frequent use of oxygen. Regarding patient outcome, 34 patients continued NPPV (64%), and there were three discontinues (6%), seven tracheostomies (13%), and nine deaths (17%). The continuation rate was high among those with neuromuscular disorders (15/19 cases, 79%) and that of tracheotomy was high in those with metabolic/degenerative diseases (3/9 cases, 33%). Ten patients transitioned to adult care, accounting for 29% of the 34 continuing patients.

Conclusion: This is the first observational study on long-term NPPV use in children in Japan that examined outcomes in patients with a range of disorders. The initiation situation, management, and outcomes differed between patients with neuromuscular and non-neuronal muscular diseases. Long-term use of NPPV is possible in many cases, including children with SMID, but can be challenging to continue in patients with progressive diseases such as metabolic/degenerative diseases. Careful discussions regarding the management of each patient are necessary.
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http://dx.doi.org/10.1016/j.braindev.2018.03.006DOI Listing
August 2018

Japanese Leigh syndrome case treated with EPI-743.

Brain Dev 2018 Feb 12;40(2):145-149. Epub 2017 Sep 12.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan; Department of Pediatrics, Jichi Medical University, Tochigi, Japan. Electronic address:

Background: Leigh syndrome is a mitochondrial disease caused by respiratory chain deficiency, and there are no proven effective therapies. EPI-743 is a potent cellular oxidative stress protectant and results of clinical trials for mitochondrial diseases are accumulating.

Case: At 5months, a girl presented with the scarce eye movement and diminished muscle tone. She was diagnosed with Leigh encephalopathy from blood and cerebrospinal fluid lactate elevation and MRI findings. Sequence analysis for mitochondrial DNA revealed a T10158C mutation in the mitochondrial encoded ND3 gene in complex I.

Results: At 8months, succinate was prescribed expected to restore the electron transport chain system. After that her condition got worse and succinate was discontinued. Subsequent administration of EPI-743 improved her eye movement, fine motor movements of the extremities, and bowel movement. She is now 5years old. Although brain atrophy has progressed, she has still respiratory free time.

Conclusion: Our patient showed visible improvement with EPI-743 treatment and the only patient surviving after 4years. There is a possibility that EPI-743 is modifying the natural course of the syndrome.
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http://dx.doi.org/10.1016/j.braindev.2017.08.005DOI Listing
February 2018

Sporadic infantile-onset spinocerebellar ataxia caused by missense mutations of the inositol 1,4,5-triphosphate receptor type 1 gene.

J Neurol 2015 May 21;262(5):1278-84. Epub 2015 Mar 21.

Department of Child Neurology, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo, 187-8551, Japan,

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.
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http://dx.doi.org/10.1007/s00415-015-7705-8DOI Listing
May 2015

Mutations in the glutaminyl-tRNA synthetase gene cause early-onset epileptic encephalopathy.

J Hum Genet 2015 Feb 4;60(2):97-101. Epub 2014 Dec 4.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.

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.
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http://dx.doi.org/10.1038/jhg.2014.103DOI Listing
February 2015

A Japanese girl with an early-infantile onset vanishing white matter disease resembling Cree leukoencephalopathy.

Brain Dev 2015 Jun 27;37(6):638-42. Epub 2014 Oct 27.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan; Department of Pediatrics, Jichi Medical School, Shimotsuke, Japan.

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 3days after an oral poliovirus vaccination at the age of 4months. 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 eIF2Bε 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 eIF2Bε caused by R195H as well as by I408T mutations.
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http://dx.doi.org/10.1016/j.braindev.2014.10.002DOI Listing
June 2015

Seizure recurrence following pyridoxine withdrawal in a patient with pyridoxine-dependent epilepsy.

Brain Dev 2015 Apr 7;37(4):442-5. Epub 2014 Aug 7.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan; Department of Pediatrics, Jichi Medical School, Shimotsuke, Tochigi, Japan. Electronic address:

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 α-aminoadipic semialdehyde to α-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.
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http://dx.doi.org/10.1016/j.braindev.2014.07.008DOI Listing
April 2015

Effect of CYP2C19 polymorphisms on stiripentol administration in Japanese cases of Dravet syndrome.

Brain Dev 2015 Feb 10;37(2):243-9. Epub 2014 May 10.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan; Department of Pediatrics, Jichi Medical University, Shimotsuke, Japan. Electronic address:

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 concentration/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.
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http://dx.doi.org/10.1016/j.braindev.2014.04.003DOI Listing
February 2015

Refinement of the deletion in 8q22.2-q22.3: the minimum deletion size at 8q22.3 related to intellectual disability and epilepsy.

Am J Med Genet A 2014 Aug 6;164A(8):2104-8. Epub 2014 May 6.

Division of Medical Genetics, Kanagawa Children's Medical Center, Yokohama, Japan.

Kuechler et al. [2011] reported five patients with interstitial deletions in 8q22.2-q22.3 who had intellectual disability, epilepsy, and dysmorphic features. We report on a new patient with the smallest overlapping de novo deletion in 8q22.3 and refined the phenotype. The proposita was an 8-year-old girl, who developed seizures at 10 months, and her epileptic seizure became severe and difficult to control with antiepileptic drugs. She also exhibited developmental delay and walked alone at 24 months. She was referred to us for evaluation for developmental delay and epilepsy at the age of 8 years. She had intellectual disability (IQ 37 at 7 years) and autistic behavior, and spoke two word sentences at 8 years. She had mild dysmorphic features, including telecanthus and thick vermilion of the lips. Array comparative genomic hybridization detected a 1.36 Mb deletion in 8q22.3 that encompassed RRM2B and NCALD, which encode the small subunit of p53-inducible ribonucleotide reductase and neurocalcin delta in the neuronal calcium sensor family of calcium-binding proteins, respectively. The minimum overlapping region between the present and previously reported patients is considered to be a critical region for the phenotype of the deletion in 8q22.3. We suggest that the deletion in 8q22.3 may represent a clinically recognizable condition, which is characterized by intellectual disability and epilepsy.
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http://dx.doi.org/10.1002/ajmg.a.36604DOI Listing
August 2014

PIGA mutations cause early-onset epileptic encephalopathies and distinctive features.

Neurology 2014 May 4;82(18):1587-96. Epub 2014 Apr 4.

From the Department of Pediatrics (M.K., K.H.), Yamagata University Faculty of Medicine, Yamagata; Department of Human Genetics (H.S., C.O., M.N., Y.T., N. Miyake, N. Matsumoto), Yokohama City University Graduate School of Medicine, Yokohama; Department of Immunoregulation (Y.M., T.K.), Research Institute for Microbial Diseases, and WPI Immunology Frontier Research Center, Osaka University, Suita; Division of Neurology (K.K., R.M., S.-i.H.), Saitama Children's Medical Center, Saitama; Division of Neurology (S.W.), Miyagi Children's Hospital, Sendai; Division of Neurology (M.I., H.O.), Clinical Research Institute, Kanagawa Children's Medical Center, Yokohama; Department of Pediatrics (K.M.), Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama; Department of Pediatrics (R.T.), Aomori Prefectural Central Hospital, Aomori; and Department of Pediatrics (H.O.), Jichi Medical School, Tochigi, Japan.

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.
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http://dx.doi.org/10.1212/WNL.0000000000000389DOI Listing
May 2014

A rapid screening with direct sequencing from blood samples for the diagnosis of Leigh syndrome.

Mol Genet Metab Rep 2014 1;1:133-138. Epub 2014 Apr 1.

Division of Neurology, Kanagawa Children's Medical Center, 2-138-4 Mutsukawa, Minami-ku, Yokohama, Kanagawa 232-8555, Japan; Department of Pediatrics, Jichi Medical School, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.

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.
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http://dx.doi.org/10.1016/j.ymgmr.2014.02.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121298PMC
April 2014

[Clinical profile of persistent generalized muscle contraction following the insult of developing brain].

No To Hattatsu 2014 Jan;46(1):10-5

Objective: Persons with severe motor and intellectual disabilities (SMID) caused by injury to the developing brain sometimes present generalized hypertonia in a specific position with extreme muscle overactivity persisting for most of the time during wakefulness. This "persistent generalized muscle contraction" is often associated with bad humor, sleep disturbance, hyperhidrosis, wasting, elevation of serum creatine kinase levels, regular daytime use of hypnotic or sedative medication, and the necessity to maintain the neck or hip in a flexed position manually. The aim of this study is to elucidate the clinical profile of this condition.

Methods: We retrospectively examined the medical records and brain imaging data of 66 SMID patients in the state of persistent generalized muscle contraction.

Results: Most patients could be classified into 2 major categories on the basis of clinical presentation and brain imaging: (A) those with premature birth and bilateral lesion of globus pallidus interna (kernicterus) (n = 16), and (B) those with various widespread bilateral basal ganglia/thalamic and/or cerebral lesions such as hypoxia-ischemia, acute encephalopathy, malformation, etc (n = 50). Group A assumed an asymmetrical tonic-neck-reflex-like position, torsion of the trunk, fluctuation of hypertonia, and better mental development. Three of them exhibited extreme hypertonia resembling status dystonicus. Group B often exhibited persistent and fixed retroflexion of the neck and trunk or opisthotonus. Drugs such as oral muscular relaxants were ineffective in both groups. Injection of botulinum toxin into the cervical and paravertebral muscles partially alleviated symptoms.

Conclusions: Persistent generalized muscle contraction in SMID has at least two different types. Group A has characteristics of severe dystonic hypertonia that could lead to status dystonicus. Group B might have peculiar characteristics of muscle overactivity triggered by wakefulness or discomfort, which probably results from inability to achieve spontaneous muscle relaxation.
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January 2014

De novo mutations in SLC35A2 encoding a UDP-galactose transporter cause early-onset epileptic encephalopathy.

Hum Mutat 2013 Dec 15;34(12):1708-14. Epub 2013 Oct 15.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, Kanazawa-ku, Yokohama, 236-0004, Japan.

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.
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http://dx.doi.org/10.1002/humu.22446DOI Listing
December 2013

Diagnostic utility of whole exome sequencing in patients showing cerebellar and/or vermis atrophy in childhood.

Neurogenetics 2013 Nov 4;14(3-4):225-32. Epub 2013 Oct 4.

Department of Human Genetics, Graduate School of Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan,

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.
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http://dx.doi.org/10.1007/s10048-013-0375-8DOI Listing
November 2013

Urine screening for patients with developmental disabilities detected a patient with creatine transporter deficiency due to a novel missense mutation in SLC6A8.

Brain Dev 2014 Aug 14;36(7):630-3. Epub 2013 Sep 14.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

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.
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http://dx.doi.org/10.1016/j.braindev.2013.08.004DOI Listing
August 2014

Molecular analysis of the genes causing recessive demyelinating Charcot-Marie-Tooth disease in Japan.

J Hum Genet 2013 May 7;58(5):273-8. Epub 2013 Mar 7.

Department of Pediatrics, Yamagata University School of Medicine, Yamagata, Japan.

Charcot-Marie-Tooth disease (CMT), the most common hereditary neuropathy, has been classified into two types, demyelinating and axonal types. We previously analyzed the genes causing dominant demyelinating CMT in 227 Japanese patients to identify the genetic background, but could not find any mutations in 110 patients. To investigate the frequency of patients with autosomal recessive demyelinating CMT (CMT4) mutations, we analyzed the coding sequence of known causative genes of CMT4 in 103 demyelinating CMT patients, excluding seven patients owing to lack of specimens. We found one patient with a GDAP1 mutation, one patient with an MTMR2 mutation, two patients with SH3TC2/KIAA1985 mutations and three patients with FGD4 mutations. Twelve patients, including five previously detected patients with PRX mutations, were diagnosed as CMT4, accounting for 5.5% of demyelinating CMT. In the patient with GDAP1 mutation, only one mutation inherited from his mother was detected by genomic sequencing. Analysis by reverse transcription polymerase chain reaction using messenger RNA (mRNA) from the patient's leukocytes revealed the absence of transcription from the allele inherited from his father, suggesting the existence of one more mutation leading to a lack or destabilization of mRNA. Most patients carrying CMT4 gene mutations present with early-onset and slowly progressive symptoms, which may be associated with the function of mutants. We could not identify the disease-causing gene in 96 patients (about 45%). Further studies including studies with next-generation sequencers will be required to identify the causative gene in Japanese CMT.
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http://dx.doi.org/10.1038/jhg.2013.15DOI Listing
May 2013

A child with three episodes of reversible splenial lesion.

Neuropediatrics 2013 Aug 19;44(4):199-202. Epub 2012 Dec 19.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

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.
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http://dx.doi.org/10.1055/s-0032-1330854DOI Listing
August 2013

Neuropathology of leukoencephalopathy with brainstem and spinal cord involvement and high lactate caused by a homozygous mutation of DARS2.

Brain Dev 2013 Apr 5;35(4):312-6. Epub 2012 Jun 5.

Division of Child Neurology, Kanagawa Children's Medical Center, Japan.

We diagnosed three siblings from consanguineous east Asian parents with leukoencephalopathy with brainstem and spinal cord involvement and high lactate (LBSL) from characteristic MRI, MRS findings and a homozygous mutation in the DARS2 gene. The neurological symptoms of the three patients consisted of psychomotor developmental delay, cerebellar ataxia since infancy, spasticity in the initial phase and peripheral neuropathy in later stages. Their mental development was delayed, but did not deteriorate. MRI signal abnormalities included the same abnormalities reported previously but tended to be more extensive. Signal abnormalities in the cerebral and cerebellar white matter were homogeneous and confluent from early stages. In addition, other tract such as the central tegmental tract was involved. Furthermore, an atrophic change in the cerebral white matter was observed on follow-up in one case. Two of the patients were autopsied and neuropathological findings revealed characteristic vacuolar changes in the white matter of the cerebrum, cerebellum and the nerve tracts of the brain stem and spinal cord. The central myelin sheath showed intralamellar splitting by electron microscopy. These findings were consistent to a spongy degeneration in the diffuse white matter of the brain, or spongiform leukoencephalopathy. In addition, peripheral nerves showed both axonal degeneration and abnormal myelin structures. We discussed the relationship between deficits in mitochondrial aspartyl-tRNA synthetase activity and the neuropathology observed.
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http://dx.doi.org/10.1016/j.braindev.2012.05.007DOI Listing
April 2013

Spastic quadriplegia in Down syndrome with congenital duodenal stenosis/atresia.

Congenit Anom (Kyoto) 2012 Jun;52(2):78-81

Division of Medical Genetics, Institute for Clinical Research, Kanagawa Children's Medical Center, Yokohama, Japan.

Down syndrome is an autosomal chromosome disorder, characterized by intellectual disability and muscle hypotonia. Muscle hypotonia is observed from neonates to adulthood in Down syndrome patients, but muscle hypertonicity is extremely unusual in this syndrome. During a study period of nine years, we found three patients with severe spastic quadriplegia among 20 cases with Down syndrome and congenital duodenal stenosis/atresia (3/20). However, we could find no patient with spastic quadriplegia among 644 cases with Down syndrome without congenital duodenal stenosis/atresia during the same period (0/644, P < 0.05). Further, we did not find any cases with spastic quadriplegia among 17 patients with congenital duodenal stenosis/atresia without Down syndrome admitted during the same period to use as a control group (0/17, P < 0.05). Our results suggest that congenital duodenal stenosis/atresia is a potential risk factor for spastic quadriplegia in patients with Down syndrome. Long-term survival is improving, and the large majority of people with Down syndrome are expected to live well into adult life. Management and further study for the various problems, representing a low prevalence but serious and specific to patients with Down syndrome, are required to improve their quality of life.
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http://dx.doi.org/10.1111/j.1741-4520.2012.00357.xDOI Listing
June 2012

Contiguous deletion of SLC6A8 and BAP31 in a patient with severe dystonia and sensorineural deafness.

Mol Genet Metab 2012 May 5;106(1):43-7. Epub 2012 Mar 5.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

We report here a 6-year-old boy exhibiting severe dystonia, profound intellectual and developmental disability with liver disease, and sensorineural deafness. A deficient creatine peak in brain (1)H-MR spectroscopy and high ratio of creatine/creatinine concentration in his urine lead us to suspect a creatine transporter (solute carrier family 6, member 8; SLC6A8) deficiency, which was confirmed by the inability to take up creatine into fibroblasts. We found a large ~19 kb deletion encompassing exons 5-13 of SLC6A8 and exons 5-8 of the B-cell receptor-associated protein (BAP31) gene. This case is the first report in which the SLC6A8 and BAP31 genes are both deleted. The phenotype of BAP31 mutations has been reported only as a part of Xq28 deletion syndrome or contiguous ATP-binding cassette, sub-family D, member 1 (ABCD1)/DXS1375E (BAP31) deletion syndrome [MIM ID #300475], where liver dysfunction and sensorineural deafness have been suggested to be attributed to the loss of function of BAP31. Our case supports the idea that the loss of BAP31 is related to liver dysfunction and hearing loss.
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http://dx.doi.org/10.1016/j.ymgme.2012.02.018DOI Listing
May 2012

Two Japanese patients with Leigh syndrome caused by novel SURF1 mutations.

Brain Dev 2012 Nov 10;34(10):861-5. Epub 2012 Mar 10.

Division of Neurology, Kanagawa Children's Medical Center, Minami-ku, Yokohama 232-8555, Japan.

We report two patients with Leigh syndrome that showed a combination of facial dysmorphism and MRI imaging indicating an SURF1 deficiency, which was confirmed by sequence analysis. Case 1 is a 3-year-old girl with failure to thrive and developmental delay. She presented with tachypnea at rest and displayed facial dysmorphism including frontal bossing, lateral displacement of inner canthi, esotropia, maxillary hypoplasia, slightly upturned nostril, and hypertrichosis dominant on the forehead and extremities. Case 2 is an 8-year-old boy with respiratory failure. He had been diagnosed as selective complex IV deficiency. Case 2 displayed facial dysmorphism and hypertrichosis. Since both patients displayed characteristic facial dysmorphism and MRI findings, we sequenced the SURF1 gene and identified two heterozygous mutations; c.49+1 G>T and c.752_753del in Case 1, and homozygous c.743 C>A in Case 2. For patients with Leigh syndrome showing these facial dysmorphism and hypertrichosis, sequence analysis of the SURF1 gene may be useful.
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http://dx.doi.org/10.1016/j.braindev.2012.02.007DOI Listing
November 2012

[Clinical characteristics of acute encephalopathies associated with influenza H1N1-2009 in children].

No To Hattatsu 2012 Jan;44(1):35-40

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Kanagawa.

We report 12 cases of acute encephalopathy associated with influenza H1N1-2009 treated according to Japanese guideline (2009). In all 12 cases, electroencephalogram presented diffuse or localized high-amplitude slow waves. Brain CT and MRI showed abnormalities in 4 and 6 cases, respectively. We used hypothermia therapy for 5 patients. One patient showed impairment in short term memory, while the rest of the patients showed no sequelae. These 12 cases presented here suggest the early recognition and therapy according to the newly proposed guideline may reduce severe sequelae and mortality by acute encephalopathy associated with influenza H1N1-2009.
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January 2012

A case of Sjögren-Larsson syndrome with minimal MR imaging findings facilitated by proton spectroscopy.

Pediatr Radiol 2012 Mar 29;42(3):380-2. Epub 2011 Jun 29.

Department of Radiology, Kanagawa Children's Medical Center, 2-138-4 Mutsukawa, Minami-ku, Yokohama 232-8555, Japan.

We present a 5-year-old girl who was ultimately diagnosed with Sjögren-Larsson syndrome (SLS). Although her MRI findings were minimal compared to previously published cases, prominent and characteristic abnormal lipid peaks on single-voxel proton MR spectroscopy ((1)H-MRS) facilitated the diagnosis. This case emphasizes the importance and usefulness of (1)H-MRS in diagnosing SLS.
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http://dx.doi.org/10.1007/s00247-011-2156-6DOI Listing
March 2012

Paradoxical increase in seizure frequency with valproate in nonketotic hyperglycinemia.

Brain Dev 2012 Jan 12;34(1):72-5. Epub 2011 Feb 12.

Division of Neurology, Kanagawa Children's Medical Center, Yokohama, Japan.

Nonketotic hyperglycinemia (NKH), or glycine encephalopathy, is an autosomal recessive disorder caused by a defect in the glycine cleavage enzyme system. In neonatal-onset NKH, patients manifest lethargy, hypotonia, apnea, and intractable epileptic seizures that are not specific to this disease. We experienced a 6-year-old girl with spastic quadriplegia, intractable epilepsy, and mental retardation, all initially regarded as sequelae of neonatal meningitis. The seizure frequency was transiently increased when valproate was started. Head MRI revealed progressive brain atrophy and white matter loss with high intensity signals on T2-weighted and diffusion-weighted images, which prompted us to conduct further metabolic workups. High glycine levels led us to suspect NKH, and we confirmed this diagnosis by the non-invasive, (13)C-glycine breath test. DNA sequencing revealed novel Leu885Pro/Trp897Cys mutations in the glycine decarboxylase gene that were transmitted from both parents. Sodium benzoate and dextromethorphan dramatically decreased her hypertonicity. Our case shows that paradoxical increases in seizure frequency following valproate can be a clue for a diagnosis of NKH, and that a correct diagnosis of NKH can greatly alter the quality of life in such patients.
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http://dx.doi.org/10.1016/j.braindev.2011.01.005DOI Listing
January 2012