Pallidal deep brain stimulation for patients with myoclonus-dystonia without SGCE mutations

BACKGROUND

Pallidal deep brain stimulation (GPi-DBS) is effective for treating myoclonus and dystonia caused by SGCE mutations (DYT-SGCE, DYT11). However, it is unknown whether GPi-DBS is effective for the treatment of myoclonus-dystonia which is not associated with the SGCE gene mutations. In this study, we investigated the efficacy of GPi-DBS in treating myoclonus-dystonia in SGCE mutation-negative cases.

METHODS

Three patients with myoclonus-dystonia without SGCE mutations who underwent GPi-DBS were evaluated preoperatively and 6 months postoperatively using the Unified Myoclonus Rating Scale (UMRS) and Fahn-Marsden Dystonia Rating Scale (FMDRS) for myoclonus and dystonia, respectively. In two of the three patients, myoclonus was more evident during action. Myoclonus was predominant at rest in the other patient, and he was unaware of his dystonia symptoms. The results were compared with those of the four DYT-SGCE cases.

RESULTS

The mean UMRS score in patients with myoclonus-dystonia without SGCE mutations improved from 61.7 to 33.7 pre- and postoperatively, respectively, and the mean FMDRS score improved from 7.2 to 4.5. However, the degree of improvement in myoclonus-dystonia in patients without SGCE mutations was inferior to that in patients with DYT-SGCE (the UMRS score improved by 45% and 69%, respectively).

CONCLUSIONS

GPi-DBS is effective for treating myoclonus-dystonia in patients with and without SGCE mutations. GPi-DBS should be considered as a treatment option for myoclonus-dystonia without SGCE mutations.

Vagus Nerve Stimulation Therapy for Drug-Resistant Epilepsy in Children-A Literature Review

Vagus nerve stimulation (VNS) is a palliative treatment for drug-resistant epilepsy (DRE) that has been in use for over two decades. VNS suppresses epileptic seizures, prevents emotional disorders, and improves cognitive function and sleep quality, a parallel effect associated with the control of epileptic seizures. The seizure suppression rate with VNS increases monthly to annually, and the incidence of side effects reduces over time. This method is effective in treating DRE in children as well as adults, such as epilepsy associated with tuberous sclerosis, Dravet syndrome, and Lennox-Gastaut syndrome. In children, it has been reported that seizures decreased by >70% approximately 8 years after initiating VNS, and the 50% responder rate was reported to be approximately 70%. VNS regulates stimulation and has multiple useful systems, including self-seizure suppression using magnets, additional stimulation using an automatic seizure detection system, different stimulation settings for day and night, and an automatic stimulation adjustment system that reduces hospital visits. VNS suppresses seizures and has beneficial behavioral effects in children with DRE. This review describes the VNS system, the mechanism of the therapeutic effect, the specific stimulation adjustment method, antiepileptic effects, and other clinical effects in patients with childhood DRE.

Bi-allelic SNAPC4 variants dysregulate global alternative splicing and lead to neuroregression and progressive spastic paraparesis

The vast majority of human genes encode multiple isoforms through alternative splicing, and the temporal and spatial regulation of those isoforms is critical for organismal development and function. The spliceosome, which regulates and executes splicing reactions, is primarily composed of small nuclear ribonucleoproteins (snRNPs) that consist of small nuclear RNAs (snRNAs) and protein subunits. snRNA gene transcription is initiated by the snRNA-activating protein complex (SNAPc). Here, we report ten individuals, from eight families, with bi-allelic, deleterious SNAPC4 variants. SNAPC4 encoded one of the five SNAPc subunits that is critical for DNA binding. Most affected individuals presented with delayed motor development and developmental regression after the first year of life, followed by progressive spasticity that led to gait alterations, paraparesis, and oromotor dysfunction. Most individuals had cerebral, cerebellar, or basal ganglia volume loss by brain MRI. In the available cells from affected individuals, SNAPC4 abundance was decreased compared to unaffected controls, suggesting that the bi-allelic variants affect SNAPC4 accumulation. The depletion of SNAPC4 levels in HeLa cell lines via genomic editing led to decreased snRNA expression and global dysregulation of alternative splicing. Analysis of available fibroblasts from affected individuals showed decreased snRNA expression and global dysregulation of alternative splicing compared to unaffected cells. Altogether, these data suggest that these bi-allelic SNAPC4 variants result in loss of function and underlie the neuroregression and progressive spasticity in these affected individuals.

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.

[Current practices of transition from pediatric to adult health care for patients with neurological disease: promote the cooperation between child and adult neurologists]

The Special Committee for Measures Against Transition from Pediatric to Adult Health Care of the Japanese Society of Neurology, which consists of child and adult neurologists, started to tackle the issues of pediatric to adult health care transition for patients with neurological disease in July 2020. The Committee held a workshop with a theme of "cooperation between child and adult neurologists," which is a critical issue in the pediatric to adult health care transition. To solve the many problems in the pediatric to adult health care transition, it is crucial that child and adult neurologists and primary care physicians cooperate on the following issues: preparing child neurologists for the transition, encouraging adult neurologists to study child neurology, promoting the formation of multidisciplinary teams, improving the medical system and medical fees, appealing to governmental agencies for issues of community health care and welfare services.

Safety and efficacy of avalglucosidase alfa in individuals with infantile-onset Pompe disease enrolled in the phase 2, open-label Mini-COMET study: The 6-month primary analysis report

PURPOSE

Mini-COMET (NCT03019406; Sanofi) is a phase 2, open-label, ascending-dose, 3-cohort study, evaluating avalglucosidase alfa safety, pharmacokinetics, and efficacy in individuals with infantile-onset Pompe disease aged <18 years who previously received alglucosidase alfa and showed clinical decline (cohorts 1 and 2) or suboptimal response (cohort 3).

METHODS

During a 25-week primary analysis period, cohorts 1 and 2 received avalglucosidase alfa 20 and 40 mg/kg every other week, respectively, for 6 months, whereas cohort 3 individuals were randomized (1:1) to receive avalglucosidase alfa 40 mg/kg every other week or alglucosidase alfa (current stable dose) for 6 months.

RESULTS

In total, 22 individuals were enrolled (cohort 1 [n = 6], cohort 2 [n = 5], cohort 3-avalglucosidase alfa [n = 5], and cohort 3-alglucosidase alfa [n = 6]). Median treatment compliance was 100%. None of the individuals discontinued treatment or died. Percentages of individuals with treatment-emergent adverse events were similar across dose and treatment groups. No serious or severe treatment-related treatment-emergent adverse events occurred. Trends for better motor function from baseline to week 25 were observed for 40 mg/kg every other week avalglucosidase alfa compared with either 20 mg/kg every other week avalglucosidase alfa or alglucosidase alfa up to 40 mg/kg weekly.

CONCLUSION

These data support the positive clinical effect of avalglucosidase alfa in patients with infantile-onset Pompe disease previously declining on alglucosidase alfa.

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.

Incremental changes in interhemispheric functional connectivity after two-stage corpus callosotomy in a patient with subcortical band heterotopia

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Coherence calculated from scalp EEG may be utilized to evaluate functional connectivity.

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Functional connectivity decreased stepwise after anterior/posterior callosotomy.

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Correlation was seen between functional connectivity and seizure frequency change.

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Functional connectivity may reflect seizure outcome of callosotomy.

Corpus callosotomy (CC) has been reported to be effective in reducing generalized seizures in patients with drug-resistant epilepsies. However, efficacy is measured only by seizure frequency, without any electrophysiological guidance. Herein, we conducted a quantitative analysis of interhemispheric functional connectivity using inter-electrode coherence of scalp electroencephalogram (EEG) in a clinical case of subcortical band heterotopia to evaluate its relationship with seizure frequency. In our case, seizure frequency decreased significantly after posterior CC but not after anterior CC. Inter-electrode coherence also decreased after posterior CC, suggesting it correlated with seizure frequency. This case study supports the use of inter-electrode coherence as an electrophysiological tool that is useful as predictive factor in evaluating the effectiveness of CC.

Is Generalized and Segmental Dystonia Accompanied by Impairments in the Dopaminergic System?

Background: The pathogenesis of dystonia is remarkably diverse. Some types of dystonia, such as DYT5 (DYT-GCH1) and tardive dystonia, are related to dysfunction of the dopaminergic system. Furthermore, on pathological examination, cell loss in the substantia nigra (SN) of patients with dystonia has been reported, suggesting that impaired dopamine production may be involved in DYT5 and in other types of dystonia.

Objectives: To investigate functional dopaminergic impairments, we compared patients with dystonia and those with Parkinson's disease (PD) with normal controls using neuromelanin-sensitive magnetic resonance imaging (NM-MRI) and dopamine transporter single photon emission computed tomography (DAT SPECT).

Methods: A total of 18, 18, and 27 patients with generalized or segmental dystonia, patients with PD, and healthy controls, respectively, were examined using NM-MRI. The mean area corresponding to NM in the SN (NM-SN) was blindly quantified. DAT SPECT was performed on 17 and eight patients with dystonia and PD, respectively. The imaging data of DAT SPECT were harmonized with the Japanese database using striatum phantom calibration. These imaging data were compared between patients with dystonia or PD and controls from the Japanese database in 256 healthy volunteers using the calibrated specific binding ratio (cSBR). The symptoms of dystonia were evaluated using the Fahn–Marsden Dystonia Rating Scale (FMDRS), and the correlation between the results of imaging data and FMDRS was examined.

Results: The mean areas corresponding to NM in the SN (NM-SN) were 31 ± 4.2, 28 ± 3.8, and 43 ± 3.8 pixels in patients with dystonia, PD, and in healthy controls, respectively. The mean cSBRs were 5 ± 0.2, 2.8 ± 0.2, 9.2 (predictive) in patients with dystonia, PD, and in healthy controls, respectively. The NM-SN area (r = −0.49, p < 0.05) and the cSBR (r = −0.54, p < 0.05) were inversely correlated with the FMDRS. There was no significant difference between the dystonia and PD groups regarding NM-SN (p = 0.28). In contrast, the cSBR was lower in patients with PD than in those with dystonia (p < 0.5 × 10⁻⁶).

Conclusions: Impairments of the dopaminergic system may be involved in developing generalized and segmental dystonia. SN abnormalities in patients with dystonia were supposed to be different from degeneration in PD.

Nonconvulsive status epilepticus following rotavirus gastroenteritis in two pediatric patients

BACKGROUND

Nonconvulsive status epilepticus (NCSE) comprises a range of conditions in which prolonged electrographic seizures result in nonconvulsive clinical symptoms. An understanding of NCSE is especially important in emergency care. Among the various causes of NCSE, an infectious etiology has been rarely reported to date.

CASE REPORTS

We report two pediatric cases of rotavirus gastroenteritis complicated by NCSE. In both cases, bilateral rhythmic delta activity (2.5-3 Hz) with occipital predominance fluctuated with the patient's consciousness level. The paroxysmal waves disappeared completely and consciousness immediately and remarkably improved after intravenous midazolam infusion. The patients remained alive 10 and 2 years, respectively, after short-term oral anticonvulsant administration, with no epileptic seizures.

CONCLUSION

The etiology of NCSE was identical and the clinical presentations were analogous in the two patients. The seizure semiology differed from that in benign convulsion with gastroenteritis. NCSE was considered the prominent cause of neurological symptoms; however, the pathogenic mechanism remains unclear, including the coexistence of acute encephalopathy.

Magnetic Resonance Imaging Findings in Preterm Infants With Bilirubin Encephalopathy Beyond Three Years Corrected Age

BACKGROUND

Magnetic resonance imaging (MRI) abnormalities in preterm infants with bilirubin encephalopathy (BE) become less clear as the infants age. We assessed MRI findings in children with preterm BE older than 36 months corrected age (CA).

METHODS

In a previous questionnaire survey, hospitals were asked to provide head MRI data of patients older than 36 months CA. MRI findings were reviewed by three pediatric neurology specialists and classified as no abnormalities, partial globus pallidus (GP) lesions, or diffuse GP lesions.

RESULTS

In total, 33 MRI scans were available from 28 patients. The median gestational age and birth weight were 26 weeks and 824 g, respectively. The prevalence of MRI abnormalities was 100% in patients at 37 to 48 months CA, 71% in those at 49 to 60 months CA, 50% in those at 61 to 72 months CA, 67% in those at 73 to 84 months CA, and 38% in those at 85 months CA or older. Partial GP lesions were more common than diffuse GP lesions at all ages. No significant differences in sex, gestational age, birth weight, or gross motor function impairment were observed among lesion groups.

CONCLUSIONS

GP lesions were detected on MRI in most children with preterm BE when studied after 36 months CA, although MRI abnormalities became less apparent along with age. Partial GP lesions may be a characteristic of older children with preterm BE.

Pathogenic MAST3 Variants in the STK Domain Are Associated with Epilepsy

OBJECTIVE

The MAST family of microtubule-associated serine-threonine kinases (STKs) have distinct expression patterns in the developing and mature human and mouse brain. To date, only MAST1 has been conclusively associated with neurological disease, with de novo variants in individuals with a neurodevelopmental disorder, including a mega corpus callosum.

METHODS

Using exome sequencing, we identify MAST3 missense variants in individuals with epilepsy. We also assess the effect of these variants on the ability of MAST3 to phosphorylate the target gene product ARPP-16 in HEK293T cells.

RESULTS

We identify de novo missense variants in the STK domain in 11 individuals, including 2 recurrent variants p.G510S (n = 5) and p.G515S (n = 3). All 11 individuals had developmental and epileptic encephalopathy, with 8 having normal development prior to seizure onset at <2 years of age. All patients developed multiple seizure types, 9 of 11 patients had seizures triggered by fever and 9 of 11 patients had drug-resistant seizures. In vitro analysis of HEK293T cells transfected with MAST3 cDNA carrying a subset of these patient-specific missense variants demonstrated variable but generally lower expression, with concomitant increased phosphorylation of the MAST3 target, ARPP-16, compared to wild-type. These findings suggest the patient-specific variants may confer MAST3 gain-of-function. Moreover, single-nuclei RNA sequencing and immunohistochemistry shows that MAST3 expression is restricted to excitatory neurons in the cortex late in prenatal development and postnatally.

INTERPRETATION

In summary, we describe MAST3 as a novel epilepsy-associated gene with a potential gain-of-function pathogenic mechanism that may be primarily restricted to excitatory neurons in the cortex. ANN NEUROL 2021;90:274-284.

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 β-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.

Evaluation of the Diagnostic Criteria for Anti-NMDA Receptor Encephalitis in Japanese Children

OBJECTIVE

To evaluate the validity of the 2016 clinical diagnostic criteria proposed for probable anti-NMDA receptor (NMDAR) encephalitis in children, we tested the criteria in a Japanese pediatric cohort.

METHODS

We retrospectively reviewed clinical information of patients with neurologic symptoms whose CSF was analyzed for NMDAR antibodies (NMDAR-Abs) in our laboratory from January 1, 2015, to March 31, 2019.

RESULTS

Overall, 137 cases were included. Of the 41 cases diagnosed as probable anti-NMDAR encephalitis (criteria-positive) according to the 2016 criteria, 13 were positive and 28 were negative for anti-NMDAR-Abs. Of the 96 criteria-negative cases, 3 were positive and 93 were negative for anti-NMDAR-Abs. The sensitivity of the criteria was 81.2%, specificity was 76.9%, positive predictive value (PPV) was 31.7%, and negative predictive value was 96.9%. Compared with the true-positive group, the false-positive group contained more male than female patients (male:female, 4:9 in the true-positive vs 19:9 in the false-positive group, p = 0.0425). The majority of the cases with false-positive diagnoses were associated with neurologic autoimmunity.

CONCLUSION

The clinical diagnostic criteria are reliable for deciding to start immunomodulatory therapy in the criteria-positive cases. Low PPV may be caused by a lower prevalence of NMDAR encephalitis or lower level of suspicion for encephalitis in the pediatric population. Physicians should therefore continue differential diagnosis, focusing especially on other forms of encephalitis.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that the proposed diagnostic criteria for anti-NMDAR encephalitis in children has a sensitivity of 81.2% and a specificity of 76.9%.

Auditory brainstem response in preterm infants with bilirubin encephalopathy

AIM

To clarify auditory brainstem response (ABR) in preterm infants with bilirubin encephalopathy and the relationships between ABR and clinical variables.

METHOD

We retrospectively reviewed the ABR waveforms of 56 preterm infants with BE and graded them as "no response", "abnormal interwave separation", or "normal". Patient backgrounds, the peak total bilirubin level, the bilirubin/albumin ratio, verbal communication ability, and newborn hearing screening test results from an automated ABR evaluation had been collected during an earlier nationwide survey.

RESULTS

The frequency of abnormal ABR findings decreased with age. Verbal communication tended to be poorer in patients with more severe ABR abnormalities. ABR findings improved in 7 of 29 infants with available serial ABR data. Both gestational age and the peak total bilirubin level were relatively lower in patients with than in those without improved ABR findings. Newborn hearing screening using automated ABR evaluation yielded data consistent with manual ABR findings in 16 of 20 patients who underwent both examinations.

CONCLUSIONS

ABR abnormalities in preterm infants with bilirubin encephalopathy may improve over time, especially in those with a lower gestational age and peak total bilirubin level. Newborn hearing screening using automated ABR may fail to detect abnormalities in some infants.

Valine-restricted diet for patients with ECHS1 deficiency: Divergent clinical outcomes in two Japanese siblings

BACKGROUND

ECHS1 is a key enzyme of the valine catabolic pathway and oxidation of fatty acids. In ECHS1 deficiency (ECHS1D), accumulation of toxic intermediates from the valine induces neurodegeneration, which presents Leigh syndrome (LS). Therefore, valine restriction is suggested as an effective therapy. Further, cysteamine may detoxify the toxic metabolites themselves and N-acetylcysteine (NAC) is a potent antioxidant preventing neurological affect. Herein, we report the therapeutic effects of dietary therapy, cysteamine, and NAC in two siblings with ECHS1D, including their clinical, neuroradiological, and chemical aspects.

CASE REPORT

The elder sister was the proband and was diagnosed as LS at 13 months of age. Gene analysis identified compound heterozygous ECHS1 mutations. Her psychomotor development was regressed, and she became bedridden. At 4 years old she started a low protein diet (LPD), but with no obvious neurological change. The younger brother was confirmed early with ECHS1D and received cysteamine and NAC treatment from 5 months of age, which could not prevent him developing LS at 7 months of age. Thus, we started a LPD at 14 months of age, with which he regained his ability to roll over, then we proceeded to a valine-restricted diet. The brain magnetic resonance image hyperintensity was diminished, and the lactate peak on magnetic resonance spectroscopy decreased. His neurological outcome is better than his elder sister. In both cases, excretion of valine metabolites decreased after dietary therapy without obvious adverse effects.

CONCLUSION

Early initiation of dietary therapy may reduce neurological sequelae in patients with ECHS1D.

Neonatal Jaundice in Preterm Infants with Bilirubin Encephalopathy

INTRODUCTION

The aim of this study is to clarify bilirubin parameters and its treatment in preterm infants with bilirubin encephalopathy (pBE).

METHODS

We asked the responders to an earlier nationwide Japanese survey on pBE to provide additional information. pBE was diagnosed based on the criteria used in the nationwide survey. We collected data on serum total bilirubin (TB), direct bilirubin (DB), albumin, and unbound bilirubin (UB) levels during the first 8 weeks of life, and on phototherapy and exchange transfusion treatments.

RESULTS

We obtained clinical data from 75 patients with pBE from 58 hospitals (response rate of 59%), who were born between 2002 and 2016. The average peak TB level was 12.6 mg/dL (215 μmol/L), and the average age at peak attainment was 19.7 days after birth. Albumin level was <2.5 g/dL in 44 patients, and the peak DB level was ≥2 mg/dL (34.2 μmol/L) in 20 patients. The average peak bilirubin/albumin (B/A) (mg/g) ratio was 3.8 (molar ratio of 0.475), and the average age at peak attainment was 18.6 days. The average peak UB level was 0.67 μg/dL (11.5 nmol/L). The median duration of phototherapy was 6 days, and the median day of the last session was 12. The peak TB level occurred after the last day of phototherapy in 30 of the 61 patients available for comparison.

CONCLUSIONS

Most patients with pBE lacked marked elevations in serum TB levels and the B/A ratio, the peaks of which were sometimes delayed to >4 weeks after birth.

A nationwide survey of bilirubin encephalopathy in preterm infants in Japan

OBJECTIVES

To examine the clinical characteristics of bilirubin encephalopathy in preterm infants (pBE) in Japan.

METHODS

We performed a two-step nationwide questionnaire survey. The initial survey determined the number of children with pBE. Using a structured questionnaire, the second survey clarified the clinical manifestations and characteristics of children with pBE, including the perinatal history, neonatal complications, neurological features, verbal communication, diet, and magnetic resonance imaging (MRI) and auditory brainstem response (ABR) findings.

RESULTS

The initial survey included 190 pBE infants, indicating an incidence of approximately 10 per year. Clinical information was available for 142 of them. The median gestational age was 26 weeks and the median birthweight was 883 g. As to neonatal complications, 20% had none, 25% had one complication, 54% had two or more. Head control was observed in 45% and functional gait in 8%. Purposeful hand use was seen in 41% of patients and verbal communication in 40%. MRI showed T2 hyperintensities in the globi pallidi in 111 of 136 patients, especially between 7 and 18 months of corrected age. ABR abnormalities were present in 88 of 117 patients.

CONCLUSIONS

pBE was infrequent but constantly observed during the study period, especially in very preterm infants, even in those with no severe neonatal complications. Severely impaired gross motor function and relatively preserved manual function and verbal communication were characteristic. MRI and ABR abnormalities will facilitate diagnosis.

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.

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.

A severe case of status dystonicus caused by a de novo KMT2B missense mutation

Here, we present the case of a 15-year-old Japanese girl with Dystonia 28, childhood-onset; DYT28 (MIM#606834) showing early-onset generalized progressive dystonia and status dystonicus. The patient was genetically undiagnosed and had not responded to various medications. By trio-based whole exome sequencing and in silico analyses, we identified a de novo heterozygous variant of KMT2B: NM_014727.2: c.7828C > T, p(Arg2610Cys). Globus pallidus internus deep brain stimulation (GPi-DBS) therapy was considered; however, the therapy could not be performed due to the patient's poor nutritional status and repeated infections. GPi-DBS is considered to be an effective treatment for patients with KMT2B mutations, and genetic diagnosis is important before progression to status dystonicus.

Prenatal clinical manifestations in individuals with COL4A1/2 variants

BACKGROUND

Variants in the type IV collagen gene (COL4A1/2) cause early-onset cerebrovascular diseases. Most individuals are diagnosed postnatally, and the prenatal features of individuals with COL4A1/2 variants remain unclear.

METHODS

We examined COL4A1/2 in 218 individuals with suspected COL4A1/2-related brain defects. Among those arising from COL4A1/2 variants, we focused on individuals showing prenatal abnormal ultrasound findings and validated their prenatal and postnatal clinical features in detail.

RESULTS

Pathogenic COL4A1/2 variants were detected in 56 individuals (n=56/218, 25.7%) showing porencephaly (n=29), schizencephaly (n=12) and others (n=15). Thirty-four variants occurred de novo (n=34/56, 60.7%). Foetal information was available in 47 of 56 individuals, 32 of whom (n=32/47, 68.1%) had one or more foetal abnormalities. The median gestational age at the detection of initial prenatal abnormal features was 31 weeks of gestation. Only 14 individuals had specific prenatal findings that were strongly suggestive of features associated with COL4A1/2 variants. Foetal ventriculomegaly was the most common initial feature (n=20/32, 62.5%). Posterior fossa abnormalities, including Dandy-Walker malformation, were observed prenatally in four individuals. Regarding extrabrain features, foetal growth restriction was present in 16 individuals, including eight individuals with comorbid ventriculomegaly.

CONCLUSIONS

Prenatal observation of ventriculomegaly with comorbid foetal growth restriction should prompt a thorough ultrasound examination and COL4A1/2 gene testing should be considered when pathogenic variants are strongly suspected.

Clinical characteristics of children and adults with anti-N-methyl-D-aspartate receptor encephalitis

OBJECTIVES

To investigate the clinical characteristics of children and adults with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis.

METHODS

Patients who tested positive for the anti-NMDAR antibody (by a cell-based assay) in the cerebrospinal fluid were enrolled. They were divided into two groups based on age (<16 years or older).

RESULTS

Three children (two males and one female) and four adults (one male and three females) were examined. The age at onset was 3.0 ± 1.41 years (range: 2-5 years) for the children and 31.8 ± 6.80 years (range: 20-36 years) for the adults. The follow-up duration was 82.7 ± 23.80 months (range: 52-110 months) for the children and 61.5 ± 12.54 months (range: 43-78 months) for the adults. Prodromal symptoms such as fever and headache were observed in three adults. Two children received influenza vaccination before the onset of encephalitis. Brain magnetic resonance imaging abnormalities were observed in three children and one adult. Basal ganglia lesions were observed in two children and one adult, and the two children showed dystonia. Two children and one adult without neoplasms experienced recurrences. The modified Rankin Scale scores at the final follow-up tended to be worse in children than in adults.

CONCLUSION

Three patients had basal ganglia lesions, and two of them showed dystonia. Dystonia with basal ganglia lesions has been rarely reported in anti-NMDAR encephalitis but should be noted as a significant symptom, which severely affects the activities of daily life.

A questionnaire survey on the efficacy of various treatments for dyskinetic cerebral palsy due to preterm bilirubin encephalopathy

OBJECTIVES

Preterm children with severe dyskinetic cerebral palsy due to bilirubin encephalopathy often suffer from marked generalised hypertonus as they age. We performed a questionnaire survey to investigate patient-reported outcomes of treatments for improving their activities of daily life.

METHODS

A mail questionnaire was administered to the caregivers of 67 children with preterm bilirubin encephalopathy aged >4 years. We asked about the type of treatments they received and their efficacy using a five-point subjective scale for the following five domains: motor function, postural stability, sleep, pain, and care burden. The names of oral drugs and their efficacies were also explored.

RESULTS

The response rate of the questionnaires was 62.7% (42/67), and we analysed the results from 41 validated cases. All children underwent rehabilitation. A total of 30 children received oral drugs, 22 botulinum toxin, 12 orthopaedic surgery, and 3 intrathecal baclofen. Each of these treatments was subjectively reported to be effective in more than half of the recipients for each of the five domains, whereas 23 (56%) required more than two types of treatments other than rehabilitation. Chlordiazepoxide was the most commonly used oral drug, by 28 children (68%), and was discontinued in 7 patients (25%) only. In the sleep domain, the rate of a positive effect was significantly higher for oral drugs (92.7%) than the other treatments (p < 0.01).

CONCLUSION

All treatments were partially effective, but their appropriate combination based on a multidisciplinary approach is essential for muscle tone management in children with preterm bilirubin encephalopathy.

Assessment and Rating of Motor Cerebellar Ataxias With the Kinect v2 Depth Sensor: Extending Our Appraisal

Current assessment of patients with cerebellar disorders is based on conventional neurological examination that is dependent on subjective judgements. Quantitative measurement of cerebellar ataxias (CAs) is essential for assessment of evidence-based treatments and the monitoring of the progress or recovery of diseases. It may provide us a useful tool to navigate future treatments for ataxia. We developed a Kinect v2. sensor system with a novel algorithm to measure and evaluate movements for two tests of Scale for the Assessment and Rating of Ataxia (SARA): the nose-finger test and gait. For the nose-finger test, we evaluated and compared accuracy, regularities and smoothness in the movements of the index finger and the proximal limbs between cerebellar patients and control subjects. For the task of walking, we evaluated and compared stability between the two groups. The precision of the system for evaluation of movements was smaller than 2 mm. For the nose-finger test, the mildly affected patients tended to show more instability than the control subjects. For a severely affected patient, our system quantified the instability of movements of the index finger using kinematic parameters, such as fluctuations and average speed. The average speed appears to be the most sensitive parameter that contrasts between patients with CAs and control subjects. Furthermore, our system also detected the adventitious movements of more proximal body parts, such as the elbow, shoulder and head. Assessment of walking was possible only in patients with mild CAs. They demonstrated large sways and compensatory wide stances. These parameters appeared to show higher accuracy than SARA. This examiner-independent device measures movements of the points of interest of SARA more accurately than eye and further provides additional information about the ataxic movements (e.g., the adventitious movements of the elbow, shoulder and head in the nose-finger test and the wide-based walking with large oscillation in the gait task), which is out of the scope of SARA. Our new system enables more accurate scoring of SARA and further provides additional information that is not currently evaluated with SARA. Therefore, it provides an easier, more accurate and more systematic description of CAs.

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.

De novo hotspot variants in CYFIP2 cause early-onset epileptic encephalopathy

OBJECTIVE

The cytoplasmic fragile X mental retardation 1 interacting proteins 2 (CYFIP2) is a component of the WASP-family verprolin-homologous protein (WAVE) regulatory complex, which is involved in actin dynamics. An obvious association of CYFIP2 variants with human neurological disorders has never been reported. Here, we identified de novo hotspot CYFIP2 variants in neurodevelopmental disorders and explore the possible involvement of the CYFIP2 mutants in the WAVE signaling pathway.

METHODS

We performed trio-based whole-exome sequencing (WES) in 210 families and case-only WES in 489 individuals with epileptic encephalopathies. The functional effect of CYFIP2 variants on WAVE signaling was evaluated by computational structural analysis and in vitro transfection experiments.

RESULTS

We identified three de novo CYFIP2 variants at the Arg87 residue in 4 unrelated individuals with early-onset epileptic encephalopathy. Structural analysis indicated that the Arg87 residue is buried at an interface between CYFIP2 and WAVE1, and the Arg87 variant may disrupt hydrogen bonding, leading to structural instability and aberrant activation of the WAVE regulatory complex. All mutant CYFIP2 showed comparatively weaker interactions to the VCA domain than wild-type CYFIP2. Immunofluorescence revealed that ectopic speckled accumulation of actin and CYFIP2 was significantly increased in cells transfected with mutant CYFIP2.

INTERPRETATION

Our findings suggest that de novo Arg87 variants in CYFIP2 have gain-of-function effects on the WAVE signaling pathway and are associated with severe neurological disorders. Ann Neurol 2018;83:794-806.

[Ataxia Telangiectasia]

Ocular telangiectasias are pathognomonic of ataxia telangiectasia (AT), and they usually appear after 6 years of age. Skin and visceral telangiectasias may appear with advancing age. They may represent a progeric change. When present, ocular telangiectasias facilitate the clinical diagnosis of AT, but they are minimally present or absent in milder variants.

Genetic landscape of Rett syndrome-like phenotypes revealed by whole exome sequencing

Background

Rett syndrome (RTT) is a characteristic neurological disease presenting with regressive loss of neurodevelopmental milestones. Typical RTT is generally caused by abnormality of methyl-CpG binding protein 2 (MECP2). Our objective to investigate the genetic landscape of MECP2-negative typical/atypical RTT and RTT-like phenotypes using whole exome sequencing (WES).

Methods

We performed WES on 77 MECP2-negative patients either with typical RTT (n=11), atypical RTT (n=22) or RTT-like phenotypes (n=44) incompatible with the RTT criteria.

Results

Pathogenic or likely pathogenic single-nucleotide variants in 28 known genes were found in 39 of 77 (50.6%) patients. WES-based CNV analysis revealed pathogenic deletions involving six known genes (including MECP2) in 8 of 77 (10.4%) patients. Overall, diagnostic yield was 47 of 77 (61.0 %). Furthermore, strong candidate variants were found in four novel genes: a de novo variant in each of ATPase H+ transporting V0 subunit A1 (ATP6V0A1), ubiquitin-specific peptidase 8 (USP8) and microtubule-associated serine/threonine kinase 3 (MAST3), as well as biallelic variants in nuclear receptor corepressor 2 (NCOR2).

Conclusions

Our study provides a new landscape including additional genetic variants contributing to RTT-like phenotypes, highlighting the importance of comprehensive genetic analysis.

Genetic analysis of undiagnosed ataxia-telangiectasia-like disorders

OBJECTIVES

Defects in DNA damage responses or repair mechanisms cause numerous rare inherited diseases, referred to as "DNA-repair defects" or "DNA damage deficiency", characterized by neurodegeneration, immunodeficiency, and/or cancer predisposition. Early accurate diagnosis is important for informing appropriate clinical management; however, diagnosis is frequently challenging and can be delayed, due to phenotypic heterogeneity. Comprehensive genomic analysis could overcome this disadvantage. The objectives of this study were to determine the prevalence of ataxia-telangiectasia (A-T) and A-T-like DNA-repair defects in Japan and to determine the utility of comprehensive genetic testing of presumptively diagnosed patients in facilitating early diagnosis.

METHODS

A nationwide survey of diseases presumably caused by DNA-repair defects, including A-T, was performed. Additionally, comprehensive next-generation sequencing (NGS) analysis, targeting known disease-causing genes, was conducted.

RESULTS

Sixty-three patients with A-T or other diseases with characteristics of DNA-repair defects were identified. Thirty-four patients were genetically or clinically definitively diagnosed with A-T (n = 22) or other DNA-repair defects (n = 12). Genetic analysis of 17 presumptively diagnosed patients revealed one case of ataxia with oculomotor apraxia type 1 (AOA1); one ataxia with oculomotor apraxia type 2 (AOA2); two types of autosomal dominant spinocerebellar ataxia (SCA5, SCA29); two CACNA1A-related ataxias; one microcephaly with or without chorioretinopathy, lymphedema, or mental retardation (MCLMR); and one autosomal dominant KIF1A-related disorder with intellectual deficit, cerebellar atrophy, spastic paraparesis, and optic nerve atrophy. The diagnostic yield was 58.8%.

CONCLUSION

Comprehensive genetic analysis of targeted known disease-causing genes by NGS is a powerful diagnostic tool for subjects with indistinguishable neurological phenotypes resembling DNA-repair defects.

De Novo Variants in the F-Box Protein FBXO11 in 20 Individuals with a Variable Neurodevelopmental Disorder

Next-generation sequencing combined with international data sharing has enormously facilitated identification of new disease-associated genes and mutations. This is particularly true for genetically extremely heterogeneous entities such as neurodevelopmental disorders (NDDs). Through exome sequencing and world-wide collaborations, we identified and assembled 20 individuals with de novo variants in FBXO11. They present with mild to severe developmental delay associated with a range of features including short (4/20) or tall (2/20) stature, obesity (5/20), microcephaly (4/19) or macrocephaly (2/19), behavioral problems (17/20), seizures (5/20), cleft lip or palate or bifid uvula (3/20), and minor skeletal anomalies. FBXO11 encodes a member of the F-Box protein family, constituting a subunit of an E3-ubiquitin ligase complex. This complex is involved in ubiquitination and proteasomal degradation and thus in controlling critical biological processes by regulating protein turnover. The identified de novo aberrations comprise two large deletions, ten likely gene disrupting variants, and eight missense variants distributed throughout FBXO11. Structural modeling for missense variants located in the CASH or the Zinc-finger UBR domains suggests destabilization of the protein. This, in combination with the observed spectrum and localization of identified variants and the lack of apparent genotype-phenotype correlations, is compatible with loss of function or haploinsufficiency as an underlying mechanism. We implicate de novo missense and likely gene disrupting variants in FBXO11 in a neurodevelopmental disorder with variable intellectual disability and various other features.

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.

Resting-State Pallidal-Cortical Oscillatory Couplings in Patients With Predominant Phasic and Tonic Dystonia

Pallidal deep brain stimulation (DBS) improves the symptoms of dystonia. The improvement processes of dystonic movements (phasic symptoms) and tonic symptoms differ. Phasic symptoms improve rapidly after starting DBS treatment, but tonic symptoms improve gradually. This difference implies distinct neuronal mechanisms for phasic and tonic symptoms in the underlying cortico-basal ganglia neuronal network. Phasic symptoms are related to the pallido-thalamo-cortical pathway. The pathway related to tonic symptoms has been assumed to be different from that for phasic symptoms. In the present study, local field potentials of the globus pallidus internus (GPi) and globus pallidus externus (GPe) and electroencephalograms from the motor cortex (MCx) were recorded in 19 dystonia patients to analyze the differences between the two types of symptoms. The 19 patients were divided into two groups, 10 with predominant phasic symptoms (phasic patients) and 9 with predominant tonic symptoms (tonic patients). To investigate the distinct features of oscillations and functional couplings across the GPi, GPe, and MCx by clinical phenotype, power and coherence were calculated over the delta (2-4 Hz), theta (5-7 Hz), alpha (8-13 Hz), and beta (14-35 Hz) frequencies. In phasic patients, the alpha spectral peaks emerged in the GPi oscillatory activities, and alpha GPi coherence with the GPe and MCx was higher than in tonic patients. On the other hand, delta GPi oscillatory activities were prominent, and delta GPi-GPe coherence was significantly higher in tonic than in phasic patients. However, there was no significant delta coherence between the GPi/GPe and MCx in tonic patients. These results suggest that different pathophysiological cortico-pallidal oscillations are related to tonic and phasic symptoms.

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.

Clinical and mutational spectrum of Japanese patients with Charcot-Marie-Tooth disease caused by GDAP1 variants

BACKGROUND

Mutations in GDAP1 are responsible for heterogeneous clinical and electrophysiological phenotypes of Charcot-Marie-Tooth disease (CMT), with autosomal dominant or recessive inheritance pattern. The aim of this study is to identify the clinical and mutational spectrum of CMT patients with GDAP1 variants in Japan.

MATERIALS AND METHODS

From April 2007 to October 2014, using three state-of-art technologies, we conducted gene panel sequencing in a cohort of 1,030 patients with inherited peripheral neuropathies (IPNs), and 398 mutation-negative cases were further analyzed with whole-exome sequencing.

RESULTS

We identified GDAP1 variants from 10 patients clinically diagnosed with CMT. The most frequent recessive variant in our cohort (5/10), c.740C>T (p.A247V), was verified to be associated with a founder event. We also detected three novel likely pathogenic variants: c.928C>T (p.R310W) and c.546delA (p.E183Kfs*23) in Case 2 and c.376G>A (p.E126K) in Case 8. Nerve conduction study or sural nerve biopsy of all 10 patients indicated axonal type peripheral neuropathy.

CONCLUSION

We identified GDAP1 variants in approximately 1% of our cohort with IPNs, and established a founder mutation in half of these patients. Our study originally described the mutational spectrum and clinical features of GDAP1-related CMT patients in Japan.

Different X-linked KDM5C mutations in affected male siblings: is maternal reversion error involved?

Genetic reversion is the phenomenon of spontaneous gene correction by which gene function is partially or completely rescued. However, it is unknown whether this mechanism always correctly repairs mutations, or is prone to error. We investigated a family of three boys with intellectual disability, and among them we identified two different mutations in KDM5C, located at Xp11.22, using whole-exome sequencing. Two affected boys have c.633delG and the other has c.631delC. We also confirmed de novo germline (c.631delC) and low-prevalence somatic (c.633delG) mutations in their mother. The two mutations are present on the same maternal haplotype, suggesting that a postzygotic somatic mutation or a reversion error occurred at an early embryonic stage in the mother, leading to switched KDM5C mutations in the affected siblings. This event is extremely unlikely to arise spontaneously (with an estimated probability of 0.39-7.5 × 10(-28) ), thus a possible reversion error is proposed here to explain this event. This study provides evidence for reversion error as a novel mechanism for the generation of somatic mutations in human diseases.

Myoclonic axial jerks for diagnosing atypical evolution of ataxia telangiectasia

BACKGROUND

Ataxia telangiectasia (A-T) is a common inherited cause of early childhood-onset ataxia, distinguished by progressive cerebellum malfunction, capillary vessel extension, and immunodeficiency. The diagnosis of A-T is sometimes difficult to establish in patients with atypical clinical evolution.

CASE REPORT

We experienced a pediatric 12-years-old female patient, who was finally diagnosed with classic A-T, demonstrating progressive dystonic-myoclonic axial jerks with ataxia as a predominant clinical feature. Oculocutaneous telangiectasias and immune status were unremarkable. Her myoclonic jerks were spontaneous or stimulus-sensitive, and partially ameliorated by levodopa treatment, but the ataxia was slowly progressive. A laboratory examination showed moderate atrophy of the vermis and cerebellum on brain magnetic resonance imaging, elevated serum alpha fetoprotein (AFP) levels, and total absence of A-T mutated (ATM) protein activity. We subsequently confirmed compound heterozygous truncating mutations of the ATM gene in this patient.

CONCLUSION

Our findings highlight the importance of recognizing dystonic-myoclonic jerks as one of the extrapyramidal signs of classic A-T. Measurement of AFP levels should be considered in patients with unexplained myoclonic jerk movements with ataxia in whom definitive diagnoses are not identified. Physicians should be aware that there are cases where typical findings of A-T may not be fulfilled.

Rituximab ameliorates anti-N-methyl-D-aspartate receptor encephalitis by removal of short-lived plasmablasts

We measured anti-N-methyl-D-aspartate receptor (NMDAR) autoantibody levels and assessed B cell subsets using multicolor flow cytometry of peripheral blood mononuclear cells (PBMCs) from a recurrent anti-NMDAR encephalitis case to evaluate the effectiveness of rituximab treatment. Rituximab depleted CD20(+) fractions of naïve and memory B cell subsets and reduced the number of CD20(-) plasmablasts. This study suggests that short-lived plasmablasts are removed by rituximab-induced depletion of the CD20(+) B cell population. Increased numbers of plasmablasts in PBMCs may be a candidate predictive factor for unfavorable prognosis of anti-NMDAR encephalitis and an indication of when to commence second-line immunotherapy.

De novo mutations in the autophagy gene WDR45 cause static encephalopathy of childhood with neurodegeneration in adulthood

Static encephalopathy of childhood with neurodegeneration in adulthood (SENDA) is a recently established subtype of neurodegeneration with brain iron accumulation (NBIA). By exome sequencing, we found de novo heterozygous mutations in WDR45 at Xp11.23 in two individuals with SENDA, and three additional WDR45 mutations were identified in three other subjects by Sanger sequencing. Using lymphoblastoid cell lines (LCLs) derived from the subjects, aberrant splicing was confirmed in two, and protein expression was observed to be severely impaired in all five. WDR45 encodes WD-repeat domain 45 (WDR45). WDR45 (also known as WIPI4) is one of the four mammalian homologs of yeast Atg18, which has an important role in autophagy. Lower autophagic activity and accumulation of aberrant early autophagic structures were demonstrated in the LCLs of the affected subjects. These findings provide direct evidence that an autophagy defect is indeed associated with a neurodegenerative disorder in humans.

Importance of CAG repeat length in childhood-onset dentatorubral-pallidoluysian atrophy

To elucidate a relationship between CAG repeat expansion length and disease progression history in patients with childhood-onset dentatorubral-pallidoluysian atrophy (DRPLA). We retrospectively evaluated information from nine Japanese patients with disease onset reported as between 6 months and 12 years of age. CAG repeat length in these patients ranged from 62 to 93. A strong correlation was confirmed for the age of disease onset, with the onset of epilepsy and involuntary movements, emergence of regression, and autonomic symptoms. The age at becoming wheelchair-bound and initiation of tube feeding also showed a significant correlation with CAG repeat length. This is the first report detailing this aspect of DRPLA focusing on the childhood-onset population. Earlier disease milestones were revealed compared to the expected age based upon a previous report that contained data from the entire patient population, including adult-onset cases (Hasegawa et al. in Mov Disord 25:1694-1700, 2010). These results provide a basis for predicting the outcome of patients in this particular age group, as well as for assessing the results of future clinical therapeutic trials.