Atypical clinical course in two patients with GNB1 variants who developed acute encephalopathy.

INTRODUCTION: Variants in the GNB1 gene, which encodes the ß1 subunit of a trimeric G protein, can cause moderate to severe psychomotor retardation. Acute encephalopathies have also been observed in patients with central nervous system abnormalities; however, severe neurological sequelae have not previously been reported. CASE PRESENTATIONS: Patient 1 was a Japanese female with a de novo GNB1 variant (c.284 T > C). At 8 months old she contracted influenza A and developed generalized convulsions. In the acute phase, brain magnetic resonance imaging (MRI) findings indicated acute encephalopathy; diffuse cerebral atrophy was present 1 month later. Although multidisciplinary treatment was administered, she had severe neurological sequelae including spastic tetraplegia, severe intellectual disabilities, and refractory epilepsy. Patient 2 was a Japanese male with a de novo GNB1 variant (c.239 T > C). He experienced an unexplained respiratory arrest aged 17 years; refractory convulsions developed. Brain MRI at 1 month showed bilateral basal ganglia high intensities; at 3 months, diffuse cerebral cortex and white matter atrophy was observed. Despite multidisciplinary treatment, he developed severe spastic tetraplegia and mental regression. DISCUSSION: We report two patients with GNB1 variants who had acute lesions on brain MRI and unexpected disease courses. In such patients with acute neurological deterioration, multidisciplinary treatment is required; patients should also be carefully observed for progression to acute encephalopathy.

Genetic and clinical features of pediatric-onset hereditary spastic paraplegia: a single-center study in Japan.

Background and purpose: Hereditary spastic paraplegias (HSPs) are a set of heterogeneous neurodegenerative disorders characterized by bilateral lower limb spasticity. They may present from infancy onwards at any time. Although next-generation sequencing has allowed the identification of many causative genes, little is known about which genes are specifically associated with pediatric-onset variants. Methods: This study retrospectively evaluated the genetic analyses, family history clinical courses, magnetic resonance imaging (MRI) findings, and electrophysiologic findings of patients diagnosed with HSP in childhood at a tertiary pediatric hospital in Japan. Genetic analyses were performed using direct sequencing, disease-associated panels, and whole-exome sequencing. Results: Of the 37 patients included, 14 had a family history of HSP and 23 had a sporadic form of the disease. In 20 patients, HSP was the pure type, whereas the remaining 17 patients had complex types of HSP. Genetic data were available for 11 of the pure-type patients and 16 of those with complex types. Of these, genetic diagnoses were possible in 5 (45%) of the pure-type and 13 (81%) of the complex-type patients. SPAST variants were found in five children, KIF1A variants in four, ALS2 variants in three, SACS and L1CAM variants in two each, and an ATL1 variant in one. One child had a 10p15.3p13 duplication. Four patients with pure-type HSPs had SPAST variants and one had an ALT1 variant. The KIF1A, ALS2, SACS, and L1CAM variants and the 10p15.3p13 duplication were seen in children with complex-type HSPs, with just one complex-type patient having a SPAST variant. The identification of brain abnormalities on MRI was significantly more common among children with complex-type (11 [69%] of 16) than pure-type HSPs (one [5%] of 19) (p < 0.001). Scores on the modified Rankin Scale for Neurologic Disability were also significantly higher among children with complex-type compared with pure-type HSPs (3.5 ± 1.0 vs. 2.1 ± 0.9, p < 0.001). Conclusion: Pediatric-onset HSP was found to be sporadic and genetic in a substantial proportion of patients. The causative gene patterns differed between children with pure-type and complex-type HSPs. The causative roles of SPAST and KIF1A variants in pure-type and complex-type HSPs, respectively, should be explored further.

Elevation of brain gamma-aminobutyric acid levels is associated with vigabatrin-associated brain abnormalities on magnetic resonance imaging.

OBJECTIVE: Vigabatrin (VGB) is an effective antiseizure medication for West syndrome. It works by irreversibly inhibiting gamma-aminobutyric acid (GABA) transaminase and increasing central GABA levels. Vigabatrin-associated brain abnormalities on magnetic resonance imaging (VABAM) are an adverse effect of VGB that has only been reported in children, but the pathophysiology of this effect is unknown. In this study, we evaluated the relationship of VGB and brain GABA levels as well as the association between VABAM and GABA. METHODS: For the 15 consecutive pediatric patients treated with VGB, free GABA, glutamine, and glutamate in cerebrospinal fluid (CSF) and plasma, GABA to creatine and phosphocreatine (Cr) peak ratio (GABA/Cr), glutamine (Gln)/Cr, and glutamate (Glu)/Cr as quantified by proton MR spectroscopy (1H-MRS) were retrospectively examined. GABA/Cr was compared with in-house normal pediatric controls. Differences in the levels of each metabolite in VABAM and non-VABAM cases were also examined. RESULTS: Thirteen of the included subjects underwent magnetic resonance imaging (MRI) and 1H-MRS, and two of them presented VABAM; both cases were very-low-birth-weight preterm infants with post-hemorrhagic hydrocephalus. CSF levels of free GABA were significantly higher in VABAM (5.26 ± 1.95 µmol/L) than in non-VABAM (0.59 ± 0.63 µmol/L) cases (P = 0.03). The GABA/Cr was significantly higher in patients with VGB (0.34 ± 0.16) than in pediatric controls (0.20 ± 0.05) (P = 0.02). The GABA/Cr tended to be higher in VABAM (0.48 ± 0.10) than in non-VABAM cases (0.31 ± 0.15) (P = 0.31). SIGNIFICANCE: Elevated brain GABA levels were observed in VABAM patients, suggesting its involvement in the pathogenesis of this condition. In particular, a marked increase in CSF-free GABA was characteristic. Although the elevation of the GABA/Cr is mild, it may be useful for early identification of patients with risk of VABAM.

Congenital disorders of glycosylation type IIb with MOGS mutations cause early infantile epileptic encephalopathy, dysmorphic features, and hepatic dysfunction.

AIM: MOGS mutations cause congenital disorders of glycosylation type IIb (CDG-IIb or GCS1-CDG). The specific manifestations caused by the mutations in this gene remain unknown. We aimed to describe the clinical features of CDG- IIb and the effectiveness of urinary oligosaccharide analysis in the diagnosis of CDG- IIb. METHODS: Patient 1 was analyzed with whole-exome sequencing (WES) to identify the causative gene of intractable epilepsy and severe developmental delay. After detecting MOGS mutation in patient 1, we analyzed patients 2 and 3 who were siblings and had clinical features similar to those in patient 1. Urinary oligosaccharide analysis was performed to confirm CDG- IIb diagnosis in patient 1. The clinical features of these patients were analyzed and compared with those in eight published cases. RESULTS: Our three patients presented with early infantile epileptic encephalopathy, generalized hypotonia, hepatic dysfunction and dysmorphic features. In two cases, compound heterozygous mutations in MOGS were identified by WES. Isolation and characterization of the urinary oligosaccharide was performed in one of these cases to confirm the diagnosis of CDG-IIb. Although the isoelectric focusing of transferrin (IEF-T) of serum in this patient was normal, urinary excretion of Hex4 corresponding to Glc3Man was observed by mass spectrometry. CONCLUSION: This report provides clinical manifestations of CDG-IIb with MOGS mutation. CDG-IIb shows a normal IEF profile of serum transferrin and cannot be detected by structural analysis of the patient's glycoproteins. Characterization of urinary oligosaccharides should be considered to detect this disorder.

Expanding the phenotype of COL4A1-related disorders-Four novel variants.

OBJECTIVE: COL4A1 variant causes severe central nervous system (CNS) anomalies, including hydranencephaly. However, the pathogenic mechanism underlying the COL4A1 phenotype remains unclear. Here, we report de novo COL4A1 variants in four Japanese patients with typical or rare CNS involvement and exhibiting diverse phenotypes. METHODS: We identified and enrolled four patients with white matter abnormalities and cerebral structural defects suggestive of cerebrovascular disease. Genetic analysis was performed using panel sequencing. RESULTS: All the patients were perinatally asymptomatic during the infantile period but exhibited developmental delay and growth retardation later. All the patients exhibited CNS symptoms, including psychomotor disability, spastic paralysis, and epilepsy. Brain magnetic resonance imaging revealed hydranencephaly (n = 1), ventriculomegaly (n = 4) associated with cerebral hemorrhage, and atretic encephalocele (n = 1). Three patients had developed congenital cataract, while two had hematuria. We identified two COL4A1 missense variants [exon32:c.2555G > A p.(Gly852Asp), exon40:c.3407G > A p.(Gly1136Asp)] and two in frame variants [exon32:c.2603_2609delinsATCCTGA p.(Ala868_Gly870delinsAspProGlu), exon36:c.3054delinsTGTAGAT p.(Leu1018delinsPheValAsp)]. The in frame variants were associated with severe CNS anomalies, hydranencephaly, and severe ventriculomegaly. Atretic encephalocele has never been reported in individuals with COL4A1 variants. CONCLUSIONS: Our findings suggest that COL4A1 variants cause variable CNS symptoms. Association between clinical phenotypes and each COL4A1 variant would clarify their underlying etiologies.

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

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.

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

Christianson syndrome (CS) is an X-linked intellectual disorder caused by mutations in the SLC9A6 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.

Discordant phenotype caused by CASK mutation in siblings with NF1.

With the advent of next-generation sequencing (NGS), a blended phenotype has been shown to be caused by multilocus molecular diagnosis. Here, we present siblings of neurofibromatosis type 1 (NF1) with discordant phenotypes. Further genetic investigation revealed that the younger sister had trisomy 8 mosaicism with a low ratio and a known pathogenic mutation in the CASK gene. This is the first report of a blended phenotype caused by NF1, CASK disorder, and trisomy 8 mosaicism.

Serial Magnetic Resonance Imaging and 1H-Magnetic Resonance Spectroscopy in GABA Transaminase Deficiency: A Case Report.

Gamma-aminobutyric acid transaminase (GABA-T) deficiency is a rare, autosomal recessive disorder characterized by severe psychomotor retardation, early-onset epileptic encephalopathy, intractable seizures, hypotonia, and hyperreflexia. The disease is caused by mutation in the 4-aminobutyrate aminotransferase (ABAT) gene, which encodes an enzyme involved in GABA catabolism. In this chapter, a 10-year follow-up of GABA-T deficiency in a rare case of a long-term survivor patient is discussed. The patient showed a progression of clinical phases with increasing age. In infancy, the patient developed psychomotor retardation and recurrent encephalopathic episodes associated with febrile illness. In early childhood, the patient presented with refractory involuntary and hyperkinetic movements and dystonic hypertonicity. In childhood, the patient gradually progressed into the chronic stable phase of the condition. Magnetic resonance imaging demonstrated high signal intensity on diffusion-weighted images involving the internal and external capsules and cerebral white matter in infancy which disappeared gradually by the age of 3 years, and showed subsequently diffuse brain atrophy in childhood. Using proton magnetic resonance spectroscopy, GABA levels in the basal ganglia were shown to be markedly elevated at the age of 1-2 years, and subsequently decreased with increasing age (toward 5 years). These findings suggest that the encephalopathic episodes in infancy and clinical severity of involuntary and hyperkinetic movements may be correlated with levels of GABA in the basal ganglia. The high levels of GABA in the cerebrospinal fluid remained unaltered, whereas levels of GABA in the serum decreased during childhood. Further investigation of long-term clinical surveillance may improve the understanding of GABA-T deficiency.

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

Phenotype of GABA-transaminase deficiency.

OBJECTIVE: We report a case series of 10 patients with γ-aminobutyric acid (GABA)-transaminase deficiency including a novel therapeutic trial and an expanded phenotype. METHODS: Case ascertainment, literature review, comprehensive evaluations, and long-term treatment with flumazenil. RESULTS: All patients presented with neonatal or early infantile-onset encephalopathy; other features were hypotonia, hypersomnolence, epilepsy, choreoathetosis, and accelerated linear growth. EEGs showed burst-suppression, modified hypsarrhythmia, multifocal spikes, and generalized spike-wave. Five of the 10 patients are currently alive with age at last follow-up between 18 months and 9.5 years. Treatment with continuous flumazenil was implemented in 2 patients. One patient, with a milder phenotype, began treatment at age 21 months and has continued for 20 months with improved alertness and less excessive adventitious movements. The second patient had a more severe phenotype and was 7 years of age at initiation of flumazenil, which was not continued. CONCLUSIONS: GABA-transaminase deficiency presents with neonatal or infantile-onset encephalopathy including hypersomnolence and choreoathetosis. A widened phenotypic spectrum is reported as opposed to lethality by 2 years of age. The GABA-A benzodiazepine receptor antagonist flumazenil may represent a therapeutic strategy.

Enhanced long-term potentiation in mature rats in a model of epileptic spasms with betamethasone-priming and postnatal N-methyl-D-aspartate administration.

OBJECTIVE: Patients with epileptic spasms are at high risk for learning and memory impairment later in life. We examined whether synaptic plasticity is affected in the adult hippocampus, a structure responsible for learning and memory, using an animal model of epileptic spasms of unknown cause. METHODS: We produced a rat model of N-methyl-d-aspartate (NMDA)-induced spasms combined with prenatal betamethasone administration. In 6- to 11-week-old rats, we evaluated the long-term potentiation (LTP) and general properties of synaptic transmission in pyramidal neurons in the CA1 area of the hippocampus in brain slices. RESULTS: The magnitude of LTP by theta burst stimulation was significantly larger in adult rats with a history of infantile NMDA injections than in control rats and rats that received additional adrenocorticotropic hormone (ACTH) treatment. The frequency of spontaneous excitatory transmission, but not inhibitory transmission, was smaller in adult rats with a history of infantile NMDA injections. SIGNIFICANCE: This study is the first to provide a basis for the alteration of synaptic plasticity and transmission in a model of epileptic spasms of unknown cause. Postnatal NMDA treatment causing epileptic spasms-like aberrant episodes in the early stage of life in rats has a latent influence on various forms of synaptic plasticity in the hippocampus. Our results provide a novel insight into cognitive impairment that appears later in life in patients with a history of epileptic spasms.

SAD-B kinase regulates pre-synaptic vesicular dynamics at hippocampal Schaffer collateral synapses and affects contextual fear memory.

Synapses of amphids defective (SAD)-A/B kinases control various steps in neuronal development and differentiation, such as axon specifications and maturation in central and peripheral nervous systems. At mature pre-synaptic terminals, SAD-B is associated with synaptic vesicles and the active zone cytomatrix; however, how SAD-B regulates neurotransmission and synaptic plasticity in vivo remains unclear. Thus, we used SAD-B knockout (KO) mice to study the function of this pre-synaptic kinase in the brain. We found that the paired-pulse ratio was significantly enhanced at Shaffer collateral synapses in the hippocampal CA1 region in SAD-B KO mice compared with wild-type littermates. We also found that the frequency of the miniature excitatory post-synaptic current was decreased in SAD-B KO mice. Moreover, synaptic depression following prolonged low-frequency synaptic stimulation was significantly enhanced in SAD-B KO mice. These results suggest that SAD-B kinase regulates vesicular release probability at pre-synaptic terminals and is involved in vesicular trafficking and/or regulation of the readily releasable pool size. Finally, we found that hippocampus-dependent contextual fear learning was significantly impaired in SAD-B KO mice. These observations suggest that SAD-B kinase plays pivotal roles in controlling vesicular release properties and regulating hippocampal function in the mature brain. Synapses of amphids defective (SAD)-A/B kinases control various steps in neuronal development and differentiation, but their roles in mature brains were only partially known. Here, we demonstrated, at mature pre-synaptic terminals, that SAD-B regulates vesicular release probability and synaptic plasticity. Moreover, hippocampus-dependent contextual fear learning was significantly impaired in SAD-B KO mice, suggesting that SAD-B kinase plays pivotal roles in controlling vesicular release properties and regulating hippocampal function in the mature brain.

Clinical pattern, mutations and in vitro residual activity in 33 patients with severe 5, 10 methylenetetrahydrofolate reductase (MTHFR) deficiency.

BACKGROUND: Severe methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare inborn defect disturbing the remethylation of homocysteine to methionine (<200 reported cases). This retrospective study evaluates clinical, biochemical genetic and in vitro enzymatic data in a cohort of 33 patients. METHODS: Clinical, biochemical and treatment data was obtained from physicians by using a questionnaire. MTHFR activity was measured in primary fibroblasts; genomic DNA was extracted from cultured fibroblasts. RESULTS: Thirty-three patients (mean age at follow-up 11.4 years; four deceased; median age at first presentation 5 weeks; 17 females) were included. Patients with very low (<1.5%) mean control values of enzyme activity (n = 14) presented earlier and with a pattern of feeding problems, encephalopathy, muscular hypotonia, neurocognitive impairment, apnoea, hydrocephalus, microcephaly and epilepsy. Patients with higher (>1.7-34.8%) residual enzyme activity had mainly psychiatric symptoms, mental retardation, myelopathy, ataxia and spasticity. Treatment with various combinations of betaine, methionine, folate and cobalamin improved the biochemical and clinical phenotype. During the disease course, patients with very low enzyme activity showed a progression of feeding problems, neurological symptoms, mental retardation, and psychiatric disease while in patients with higher residual enzyme activity, myelopathy, ataxia and spasticity increased. All other symptoms remained stable or improved in both groups upon treatment as did brain imaging in some cases. No clear genotype-phenotype correlation was obvious. DISCUSSION: MTHFR deficiency is a severe disease primarily affecting the central nervous system. Age at presentation and clinical pattern are correlated with residual enzyme activity. Treatment alleviates biochemical abnormalities and clinical symptoms partially.

[An 8-year-old boy with anti-NMDA receptor encephalitis, successfully treated with cyclophosphamide].

We report on an 8-year-old boy with non-paraneoplastic anti-NMDA receptor (NMDAR) encephalitis, who presented with psychotic symptoms and involuntary movement following an intractable seizure. His serum and CSF tested positive for anti-NMDAR antibodies. He received an initial immunotherapy consisting of methylprednisolone pulse therapy (mPSL) and intravenous immunoglobulin therapy (IVIg), without any clinical improvement. He had three cycles of monthly cyclophosphamide pulse therapy (500 mg/m2), and his clinical condition started to improve gradually two weeks after the first cycle, without any side effects. Six months after onset, he tested normal upon standard neurological examination. Cyclophosphamide therapy should be considered for children with anti-NMDAR encephalitis, as well as mPSL and IVIg.

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

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.

Acute encephalopathy in children with Dravet syndrome.

PURPOSE: The occurrence of acute encephalopathy in children with Dravet syndrome has been reported sporadically. This study clarified the features of acute encephalopathy in children with Dravet syndrome. METHODS: Through the mailing list of the Annual Zao Conference on Pediatric Neurology, we collected 15 patients with clinically diagnosed Dravet syndrome, who had acute encephalopathy, defined as a condition with decreased consciousness with or without other neurologic symptoms, such as seizures, lasting for >24 h in association with infectious symptoms. KEY FINDINGS: There were seven boys and eight girls. A mutation of the SCN1A gene was present in nine (truncation in six and missense in three). The frequency of seizures during the 3 months before the onset of acute encephalopathy was monthly in seven children and none in three. The median age at the onset of acute encephalopathy was 44 months (range 8-184 months). All children had status epilepticus followed by coma as the initial manifestation. Two different distributions of brain lesions were observed on diffusion-weighted images during the acute phase: cerebral cortex-dominant lesions with or without deep gray matter involvement and subcortical-dominant lesions. Four children died; nine survived with severe sequelae, and two had moderate sequelae. SIGNIFICANCE: We must be aware that acute encephalopathy is an important complication in children with Dravet syndrome, and associated with fulminant clinical manifestations and a poor outcome.

Paradoxical increase in seizure frequency with valproate in nonketotic hyperglycinemia.

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.