Loss-of-function mutations in SGCE found in Japanese patients with myoclonus-dystonia.

SGCE myoclonus-dystonia is a monogenic form of dystonia with an autosomal dominant mode of inheritance that co-occurs with a myoclonic jerk. In this study, we present 12 Japanese patients from nine families with this disease. Targeted next-generation sequencing covering major causative genes for monogenic dystonias identified nine distinct SGCE mutations from each of the families: three nonsense, two frameshift, two missense, one in-frame 15 bp deletion, and one splice donor site mutations, of which four were previously unreported. One missense mutation (c.662G>T, p.Gly221Val) was located at the 3' end of exon 5 (NM_001099400), which was predicted to cause aberrant splicing according to in silico predictions. Minigene assays performed together with the c.825+1G>C mutation demonstrated complete skipping of exon 5 and 6, respectively, in their transcripts. The other missense (c.1345A>G, p.Met449Val) and 15 bp deletion (c.168_182del, p.Phe58_Leu62del) mutations showed a significant reduction in cell membrane expression via HiBiT bioluminescence assay. Therefore, we concluded that all the detected mutations were disease-causing. Unlike the other detected mutations, p.Met449Val affects only isoform 3 (NP_001092870 encoded by NM_001099400) among the variously known isoforms of SGCE. This isoform is brain-specific and is mostly expressed in the cerebellum, which supports recent studies showing that cerebellar dysfunction is a key element in the pathophysiology of SGCE myoclonus-dystonia.

Genetic and clinical landscape of childhood cerebellar hypoplasia and atrophy.

PURPOSE: Cerebellar hypoplasia and atrophy (CBHA) in children is an extremely heterogeneous group of disorders, but few comprehensive genetic studies have been reported. Comprehensive genetic analysis of CBHA patients may help differentiating atrophy and hypoplasia and potentially improve their prognostic aspects. METHODS: Patients with CBHA in 176 families were genetically examined using exome sequencing. Patients with disease-causing variants were clinically evaluated. RESULTS: Disease-causing variants were identified in 96 of the 176 families (54.5%). After excluding 6 families, 48 patients from 42 families were categorized as having syndromic associations with CBHA, whereas the remaining 51 patients from 48 families had isolated CBHA. In 51 patients, 26 aberrant genes were identified, of which, 20 (76.9%) caused disease in 1 family each. The most prevalent genes were CACNA1A, ITPR1, and KIF1A. Of the 26 aberrant genes, 21 and 1 were functionally annotated to atrophy and hypoplasia, respectively. CBHA+S was more clinically severe than CBHA-S. Notably, ARG1 and FOLR1 variants were identified in 2 families, leading to medical treatments. CONCLUSION: A wide genetic and clinical diversity of CBHA was revealed through exome sequencing in this cohort, which highlights the importance of comprehensive genetic analyses. Furthermore, molecular-based treatment was available for 2 families.

Identification of two novel de novo TUBB variants in cases with brain malformations: case reports and literature review.

Heterozygous variants in TUBB encoding one of ß-tubulin isotypes are known to cause two overlapping developmental brain disorders, complex cortical dysplasia with other brain malformations (CDCBM) and congenital symmetric circumferential skin creases (CSCSC). To date, six cases of CSCSC and eight cases of CDCBM caused by nine heterozygous variants have been reported. Here we report two cases with novel de novo missense TUBB variants (NM_178014.4:c.863A>G, p.(Glu288Gly) and c.869C>T, p.(Thr290Ile)). Case 1 presented brain malformations consistent with tubulinopathies including abnormalities in cortex, basal ganglia, corpus callosum, brain stem, and cerebellum along with other systemic features such as coloboma, facial dysmorphisms, vesicoureteral reflux, hypoplastic kidney, and cutis laxa-like mild skin loosening. Another case presented abnormalities of the corpus callosum, brain stem, and cerebellum along with facial dysmorphisms. We reviewed previous literature and suggest the diversity of clinical findings of TUBB-related disorders.

Novel EXOSC9 variants cause pontocerebellar hypoplasia type 1D with spinal motor neuronopathy and cerebellar atrophy.

Pontocerebellar hypoplasia (PCH) is currently classified into 13 subgroups and many gene variants associated with PCH have been identified by next generation sequencing. PCH type 1 is a rare heterogeneous neurodegenerative disorder. The clinical presentation includes early-onset severe developmental delay, progressive motor neuronopathy, and cerebellar and pontine atrophy. Recently two variants in the EXOSC9 gene (MIM: 606180), NM_001034194.1: c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161*) were identified in four unrelated patients with PCH type 1D (PCH1D) (MIM: 618065). EXOSC9 encodes a component of the exosome complex, which is essential for correct processing and degradation of RNA. We report here two PCH1D families with biallelic EXOSC9 variants: c.239T>G (p.Leu80Arg) and c.484dupA (p.Arg162Lysfs*3) in one family and c.151G>C (p.Gly51Arg) in the other family. Although the patients studied here showed similar clinical features as previously described for PCH1D, relatively greater intellectual development (although still highly restricted) and normal pontine structure were recognized. Our findings expand the clinical consequences of biallelic EXOSC9 variants.

Disordered voluntary cough as freezing phenomenon in parkinsonism.

[Purpose] In patients with parkinsonism, the precise mechanism of impaired voluntary cough remains poorly understood. This study used the flow-volume curve to clarify whether disordered voluntary cough reflects the freezing phenomenon. [Subjects and Methods] Case 1 was a 58-year-old female who had been suffering from progressive supranuclear palsy-pure akinesia with gait freezing. Case 2 was a 59-year-old female who had advanced juvenile parkinsonism. The subjects were asked to take a deep inspiration to the total lung capacity and then cough more than five times through the face mask into the spirometer without intervening inspirations between the coughing efforts. [Results] Hesitation in cough initiation (case 2), decreased peak cough flow (case 1), and rounding of the first spike (cases 1 and 2) were observed. In addition, movements of the spike wave at a lower lung volume became progressively smaller and faster (cases 1 and 2). [Conclusion] These clinical manifestations in our patients are similar to those observed in the freezing phenomenon. However, to date, the concept of cough freezing has been underrecognized in clinical practice. From the present study, it could be hypothesized that the freezing phenomenon can occur in voluntary cough as well as in gait, speech, and writing.

Accelerometer based analysis of gait initiation failure in advanced juvenile parkinsonism: a single subject study.

[Purpose] This study used an accelerometer placed close to the center of gravity to quantitatively investigate whether unexpected gait initiation aggravates start hesitation (freezing of gait in gait initiation). [Subject and Methods] The subject was a 53-year-old female who had been suffering from juvenile parkinsonism since she was aged 21 years. An alternating-treatment design was used to compare acceleration characteristics under two gait initiation conditions, which were 1) deliberate gait initiation and 2) gait initiation on a sudden "go" verbal command (sudden gait initiation), in the "on" state of the medication cycle. [Results] In six out of eight sessions, a combination of reduced peak positive anterior accelerations and large power percentage in the high frequency band was consistently observed in the sudden gait initiation compared with deliberate gait initiation. In the other two sessions, although a large acceleration just after the "go" signal was observed, subsequent acceleration signals were blocked by sudden gait initiation. [Conclusion] The results suggest that, even in the "on" state, start hesitation is apparent without increased reliance on frontal cortical attentional mechanisms to compensate for impaired automaticity. In advanced juvenile parkinsonism, sudden gait initiation may be an effective paradigm as a provoking test for start hesitation.

Abnormal theta-band rhythm: EEG abnormality as potential biomarkers for disease severity in pediatric anti-NMDAR encephalitis.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in children often requires early immunosuppressive therapy before antibody detection. While various electroencephalogram (EEG) patterns, including extreme delta brushes (EDBs), have been reported in adults, pediatric EEG characteristics remain understudied. This study aims to assist clinicians in identifying severe cases early, potentially improving treatment outcomes through prompt intervention. This retrospective case series examined EEG features influenced by disease severity in children with anti-NMDAR encephalitis. We evaluated six children (1-13 years old; four females, two males) treated at Tokyo Metropolitan Neurological Hospital from January 2007 to January 2023. The severity of autoimmune encephalitis in our patients was assessed using the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). The literature proposes a severity classification for the CASE score, wherein scores of 0-8 points are categorized as mild, 9-18 points as moderate, and 19-27 points as severe. In our patients, CASE scores ranged from 4 to 25 (median:19). We reviewed acute-phase EEG recordings, including 13 long-term videos and 58 conventional recordings. None of the patients maintained a normal posterior-dominant rhythm, and only one exhibited EDBs. Notably, three patients with higher CASE scores (≥15) displayed abnormal theta-band rhythm during non-REM sleep and prolonged EEG recovery times. Our findings suggest that abnormal theta-band rhythms may serve as a potential acute-phase EEG biomarker for severe anti-NMDAR encephalitis in children.

Focal tonic seizures with asymmetrical posturing could allow voluntary movements: A lesson to not be misled for a non-epileptic event.

This report documents the clinical features of supplementary motor area seizures with voluntary movements in two patients. The first case describes a 13-year-old boy with a 2-year history of nocturnal seizures, characterized by an asymmetrical brief tonic posture followed by bilateral rapid hand shaking, but without impaired awareness. Magnetic resonance imaging revealed no abnormalities. Video electroencephalogram indicated interictal focal spikes and ictal activity 2 s before clinical onset in the frontal midline area. The patient stated that he purposely shook his hands to lessen the seizure-induced upper limb stiffness. The second case describes a 43-year-old man with a 33-year history of nocturnal seizures, characterized by an asymmetric brief tonic posture, with the right hand grabbing to hold this posture, but without impaired awareness. Video electroencephalogram indicated that he voluntarily moved his right hand during the latter part of the seizures; however, no clear ictal electroencephalogram change was noted. Magnetic resonance imaging revealed a mass lesion in the right medial superior frontal gyrus. Fluorodeoxyglucose-positron emission tomography and ictal single-photon emission computed tomography indicated ictal focus in the mesial frontal area, as confirmed by invasive electroencephalogram and seizure freedom after surgery. Both patients had typical supplementary motor area seizures, except they could perform voluntary movements in the body parts. The co-occurrence of supplementary motor area seizures and voluntary movements is clinically useful, as it may help avoid the inaccurate and misleading diagnosis of non-epileptic events such as psychogenic non-epileptic seizures.

Association of early-onset epileptic encephalopathy with involuntary movements - Case series and literature review.

Epileptic-dyskinetic encephalopathies are rare epilepsies characterized by early-onset epileptic encephalopathies (EOEEs) with involuntary movement. Herein, we investigated the impact of gene variants in epileptic-dyskinetic encephalopathies. Four independent patients from four families who exhibited involuntary movements were recruited from Tokyo Metropolitan Neurological Hospital. The inclusion criteria were as follows: onset within 1 year after birth, frequent seizures, severe developmental delay and accompanying involuntary movements. We detected four genetic mutations, including STXBP1, GNAO1, CYFIP2, and SCN8A variants. The involuntary movements were drug-resistant. However, pallidal electrocoagulation followed by gabapentin were partially effective in treating chorea and ballismus of the extremities in patients with GNAO1 variants, and perampanel partially suppressed seizures and involuntary movements in one patient with a SCN8A variant. Movement disorders are common to many neurodevelopmental disorders, including a variety of EOEEs. Although we could not establish a definitive correlation using genetic variants in patients with EOEE and movement disorders, involuntary movements in patients with EOEEs may be a key diagnostic finding. The usage of genetic variants could prove beneficial in the future as more patients are investigated with epileptic-dyskinetic encephalopathies.

IVIG in childhood primary angiitis of the central nervous system: A case report.

Aggressive immunosuppressive therapies have been proposed to treat primary angiitis of the central nervous system (PACNS). Here, we report the first successfully stabilized case of childhood, small-vessel PACNS with intravenous immunoglobulin (IVIG) therapy. A 12-year-old boy was admitted to our hospital complaining of recurrent headaches and upper-left homonymous quadrantanopia, since the age of 11 years. Brain computed tomography scans revealed fine calcification in the right temporal and occipital lobes. Brain magnetic resonance imaging scans revealed white matter lesions, with gadolinium enhancement, which waxed, waned, and migrated for 1 year, without immunomodulatory therapies. A cerebrospinal fluid study showed pleocytosis (12 cells per µl). No clinical or serological findings suggested systemic inflammation or vasculitis. Brain angiography was unremarkable. Brain biopsy revealed thickened and hyalinized small vessels, with intramural infiltration of inflammatory cells, which confirmed the diagnosis of small-vessel PACNS. Because the patient developed surgical site infection following biopsy, the administration of monthly IVIG (2 g/kg) was prescribed, instead of immunosuppressive agents. After IVIG therapy, the patient remained stable, except for a single episode of mild radiological exacerbation at 16 months, which occurred when the IVIG interval was expanded. Oral prednisone was added and gradually tapered. At 50 months, his intellectual abilities and motor functions were normal, although he showed residual upper-left homonymous quadrantanopia and post-exercise headache. A temporary headache, associated with the immunoglobulin infusion, was resolved by slowing the infusion rate. PACNS should be treated aggressively to improve prognosis. However, when immunosuppressants are contraindicated, IVIG may be an alternative therapeutic option.

Long-Term Evaluation of Low-Dose Betamethasone for Ataxia Telangiectasia.

BACKGROUND: Ataxia telangiectasia is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectases, immune defects, and a predisposition to malignancy. Quality of life is severely impaired by neurological symptoms. However, curative options for the neurological symptoms are limited. Recent studies have demonstrated short-term improvement in neurological symptoms with betamethasone therapy. However, the long-term and adverse effects of betamethasone are unclear. The aim of this study was to evaluate the long-term effects, benefits, and adverse effects of low-dose betamethasone in ataxia telangiectasia. METHODS: Six patients with ataxia telangiectasia received betamethasone at 0.02 mg/kg/day for two years. After cessation of betamethasone, the patients were observed for two additional years. Neurological assessments were performed, and adverse effects were monitored every three months throughout the four-year study period. RESULTS: Transient improvement of neurological symptom was observed in five of the six patients. However, after two years betamethasone treatment, only one of the six patients showed a slight improvement in the neurological score, one patient showed no change, and the neurological scores of the remaining four patients deteriorated. After the cessation of betamethasone treatment, neurological symptoms worsened in all patients. As an adverse effect of betamethasone, transient adrenal dysfunction was observed in all cases. CONCLUSIONS: Although these findings are in agreement with previous studies suggesting that short-term betamethasone treatment transiently benefits patients with ataxia telangiectasia, the long-term benefits and risks should be carefully considered.

Periventricular small cystic lesions in a patient with Coffin-Lowry syndrome who exhibited a novel mutation in the RPS6KA3 gene.

BACKGROUND: Coffin-Lowry syndrome is a rare X-linked disease, caused by loss-of-function mutations in the RPS6KA3 gene. Patients exhibit severe intellectual disability with characteristic dysmorphism. As there are no specific laboratory findings to support the diagnosis of Coffin-Lowry syndrome, it may be difficult to diagnose-especially in young children, where the characteristic craniofacial features are less discernible. CASE: Here we report on a 2-year-old boy with Coffin-Lowry syndrome with a novel missense mutation in the RPS6KA3 gene. On magnetic resonance imaging, his brain exhibited periventricular signal abnormalities with multiple small cystic lesions. These findings may aid in diagnosis of Coffin-Lowry syndrome.

Phenotype variability and allelic heterogeneity in KMT2B-Associated disease.

BACKGROUND: Mutations in Lysine-Specific Histone Methyltransferase 2B gene (KMT2B) have been reported to be associated with complex early-onset dystonia. Almost all reported KMT2B mutations occurred de novo in the paternal germline or in the early development of the patient. We describe clinico-genetic features on four Japanese patients with novel de novo mutations and demonstrate the phenotypic spectrum of KMT2B mutations. METHODS: We performed genetic studies, including trio-based whole exome sequencing (WES), in a cohort of Japanese patients with a seemingly sporadic early-onset generalized combined dystonia. Potential effects by the identified nucleotide variations were evaluated biologically. Genotype-phenotype correlations were also investigated. RESULTS: Four patients had de novo heterozygous mutations in KMT2B, c.309delG, c.1656dupC, c.3325_3326insC, and c.5636delG. Biological analysis of KMT2B mRNA levels showed a reduced expression of mutant transcript frame. All patients presented with motor milestone delay, microcephaly, mild psychomotor impairment, childhood-onset generalized dystonia and superimposed choreoathetosis or myoclonus. One patient cannot stand due to axial hypotonia associated with cerebellar dysfunction. Three patients had bilateral globus pallidal deep brain stimulation (DBS) with excellent or partial response. CONCLUSIONS: We further demonstrate the allelic heterogeneity and phenotypic variations of KMT2B-associated disease. Haploinsufficiency is one of molecular pathomechanisms underlying the disease. Cardinal clinical features include combined dystonia accompanying mild psychomotor disability. Cerebellum would be affected in KMT2B-associated disease.

Parkinsonian Symptomatology May Correlate with CT Findings before and after Shunting in Idiopathic Normal Pressure Hydrocephalus.

We aimed to investigate the characteristics of Parkinsonian features assessed by the unified Parkinson's disease rating scale (UPDRS) and determine their correlations with the computed tomography (CT) findings in patients with idiopathic normal pressure hydrocephalus (iNPH). The total score and the scores for arising from chair, gait, postural stability, and body hypokinesia in the motor examination section of UPDRS were significantly improved after shunt operations. Stepwise multiple regression analysis revealed that postural stability was the determinant of the gait domain score of the iNPH grading scale. The canonical correlation analysis between the CT findings and the shunt-responsive Parkinsonian features indicated that Evans index rather than midbrain diameters had a large influence on the postural stability. Thus, the pathophysiology of postural instability as a cardinal feature of gait disturbance may be associated with impaired frontal projections close to the frontal horns of the lateral ventricles in the iNPH patients.