Characteristics of spinal and bulbar muscular atrophy in South Korea: a cross-sectional study of 157 patients.

Spinal and bulbar muscular atrophy, namely Kennedy disease, is a rare progressive neurodegenerative disorder caused by the expansion of a CAG repeat in the first exon of the androgen receptor gene on the X chromosome. We assessed the clinical history, laboratory findings, functional scales and electrophysiological data, as well as the levels of luteinizing hormone, follicle-stimulating hormone and testosterone, in 157 Korean patients with genetically confirmed spinal and bulbar muscular atrophy (mean age at data collection = 56.9 years; range = 33-83 years). Hand tremor was the first symptom noticed by patients at a median age of 35 years, followed by gynaecomastia, orofacial fasciculation, cramps and fatigability in ascending order. Clinical symptoms such as paraesthesia and dysphagia appeared during the later stages of the disease. Cane use during ambulation began at a median age of 62 years. There were statistically significant differences between patients and controls in the results of sensory nerve studies, motor conduction velocity, and distal latencies. Furthermore, among the hormone markers analysed, the level of luteinizing hormone exhibited a negative correlation with the spinal and bulbar muscular atrophy functional rating scale, Korean version. However, among the patients with a disease duration of ≤5 years, the levels of luteinizing hormone showed a significant correlation with assessments using the amyotrophic lateral sclerosis functional rating scale-revised, spinal and bulbar muscular atrophy functional rating scale, Korean version and the 6-minute walk test. In conclusion, our findings provide clinical information from a substantial number of patients with spinal and bulbar muscular atrophy in Korea that accorded with that of patients with this disease worldwide but with updated clinical features.

Early rituximab treatment reduces long-term disability in aquaporin-4 antibody-positive neuromyelitis optica spectrum.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) causes relapsing inflammatory attacks in the central nervous system, leading to disability. As rituximab, a B-lymphocyte-depleting monoclonal antibody, is an effective in preventing NMOSD relapses, we hypothesised that earlier initiation of rituximab can also reduce long-term disability of patients with NMOSD. METHODS: This multicentre retrospective study involving 19 South Korean referral centres included patients with NMOSD with aquaporin-4 antibodies receiving rituximab treatment. Factors associated with the long-term Expanded Disability Status Scale (EDSS) were assessed using multivariable regression analysis. RESULTS: In total, 145 patients with rituximab treatment (mean age of onset, 39.5 years; 88.3% female; 98.6% on immunosuppressants/oral steroids before rituximab treatment; mean disease duration of 121 months) were included. Multivariable analysis revealed that the EDSS at the last follow-up was associated with time to rituximab initiation (interval from first symptom onset to initiation of rituximab treatment). EDSS at the last follow-up was also associated with maximum EDSS before rituximab treatment. In subgroup analysis, the time to initiation of rituximab was associated with EDSS at last follow-up in patients aged less than 50 years, female and those with a maximum EDSS score ≥6 before rituximab treatment. CONCLUSIONS: Earlier initiation of rituximab treatment may prevent long-term disability worsening in patients with NMOSD, especially among those with early to middle-age onset, female sex and severe attacks.

Neuropsychological, neuroimaging and autopsy findings of butane encephalopathy.

BACKGROUND: Butane is an aliphatic hydrocarbon used in various commercial products. While numerous reports of sudden cardiac-related deaths from butane inhalation have been described, butane-associated acute encephalopathy has rarely been reported. CASE PRESENTATION: A 38-year-old man presented with cognitive dysfunction after butane gas inhalation. Neuropsychological test results showed impairments in verbal and visual memory, and frontal executive function. Diffusion weighted MRI revealed symmetric high-signal changes in the bilateral hippocampus and globus pallidus. FDG-PET demonstrated decreased glucose metabolism in the bilateral precuneus and occipital areas and the left temporal region. At the 8-month follow-up, he showed still significant deficits in memory and frontal functions. Diffuse cortical atrophy with white matter hyperintensities and extensive glucose hypometabolism were detected on follow-up MRI and FDG-PET, respectively. Brain autopsy demonstrated necrosis and cavitary lesions in the globus pallidus. CONCLUSIONS: Only a few cases of butane encephalopathy have been reported to date. Brain lesions associated with butane encephalopathy include lesions in the bilateral thalamus, insula, putamen, and cerebellum. To the best of our knowledge, this is the first report on bilateral hippocampal and globus pallidal involvement in acute butane encephalopathy. The pathophysiology of central nervous system complications induced by butane intoxication is not yet fully understood. However, the direct toxic effects of butane or anoxic injury secondary to cardiac arrest or respiratory depression have been suggested as possible mechanisms of edematous changes in the brain after butane intoxication.

Genotype-phenotype correlations in valosin-containing protein disease: a retrospective muticentre study.

BACKGROUND: Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Paget's disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations. METHODS: Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene. RESULTS: Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8±9.6 years and mean age of onset 45.6±9.3 years. Mean diagnostic delay was 7.7±6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8±7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC <70% and being a full-time wheelchair user were associated with death. CONCLUSION: This study expands the knowledge on the phenotypic presentation, natural history, genotype-phenotype correlations and risk factors for disease progression of VCP disease and is useful to improve the care provided to patient with this complex disease.

Atypical Young-onset Dementia in Cerebral Thromboangiitis Obliterans: A Case Report.

Young-onset dementia (YOD, age at onset below 45 y) has a broad differential diagnosis. We describe a 41-year-old man with atypical manifestations of YOD syndrome in cerebral thromoboangiitis obliterans (CTAO). Extensive antemortem workup including clinical assessment, laboratory investigations, neuroimaging, and genetic testing did not elucidate a diagnosis. Postmortem neuropathologic examination revealed cortical sickle-shaped granular atrophy, resulting from numerous remote infarcts and cortical microinfarcts that mainly affected the bilateral frontal and parietal lobe, confirming CTAO. Although CTAO is a rare cause of vascular dementia, it should be considered as one of the differentials in patients with YOD with a history of heavy smoking and presence of symmetric damages of watershed-territory on neuroimaging.

Clinical, electrophysiological, and genetic characteristics of cerebrotendinous xanthomatosis in South Korea.

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disorder caused by 27-hydroxylase deficiency. We report the clinical characteristics of six Korean CTX patients. The median age of onset was 22.5 years, the median age at diagnosis was 42 years, and the diagnostic delay was 18.1 years. The most common clinical symptoms were tendon xanthoma and spastic paraplegia. Four of five patients exhibited latent central conduction dysfunction. All patients carried the same mutation in CYP27A1 (c.1214 G>A [p.R405Q]). CTX is a treatable neurodegenerative disorder; however, our results revealed that patients with CTX in Korea might receive the diagnosis after a prolonged delay. .

Episodic Vestibular Syndrome with Hyperventilation-Induced Downbeat Nystagmus.

Hyperventilation-induced downbeat nystagmus (HV-DBN) has been reported in cerebellar disorders and explained by a loss of the inhibitory cerebellar output via a metabolic effect on cerebellar Ca2+ channels. The aim of this study was to determine the clinical characteristics and underlying pathogenesis of episodic vestibular syndrome (EVS) with HV-DBN. Of 667 patients with EVS, we recruited 22 with HV-DBN and assessed their clinical characteristics, video-oculographic findings, and the results of molecular genetic analyses. The age at symptom onset was 47.5 ± 13.0 years (mean ± SD), and there was a female preponderance (n = 15, 68%). The duration of vertigo/dizziness attacks ranged from minutes to a few days, and 11 patients (50%) fulfilled the diagnostic criteria for vestibular migraine. HV-induced new-onset DBN in 8 patients, while the remaining 14 showed augmentation of spontaneous DBN by HV. The maximum slow-phase velocity of HV-DBN ranged from 2.2 to 11.9°/s, which showed a statistical difference with that of spontaneous DBN (median = 4.95, IQR = 3.68-6.55 vs. median = 1.25, IQR = 0.20-2.15, p < 0.001). HV-DBN was either purely downbeat (n = 11) or accompanied with small horizontal components (n = 11). Other neuro-otologic findings included perverted head-shaking nystagmus (n = 11), central positional nystagmus (n = 7), saccadic pursuit (n = 3), and horizontal gaze-evoked nystagmus (n = 1). Gene expression profiling with a bioinformatics analysis identified 43 upregulated and 49 downregulated differentially expressed genes (DEGs) in patients with EVS and HV-DBN and revealed that the downregulated DEGs were significantly enriched in terms related to the ribosome pathway. Our results suggest that the underlying cerebellar dysfunction would be responsible for paroxysmal attacks of vertigo in patients with EVS and HV-DBN.

Autophagic defects observed in fibroblasts from a patient with ß-propeller protein-associated neurodegeneration.

Beta-propeller protein-associated neurodegeneration (BPAN) is associated with mutations in the autophagy gene WDR45. The aim of this study was to demonstrate autophagic defects in a patient with BPAN. We assayed autophagic markers using western blot analysis and immunocytochemistry and applied transmission electron microscopy (TEM) to visualize the autophagic structures in fibroblasts from a 7-year-old Korean female with WDR45 splice-site mutation (c.977-1G>A; NM_007075.3). The protein and mRNA expression levels of WDR45 gene were decreased in the patient-derived fibroblasts. The amount of increase in LC3-II upon treatment with an autophagy inducer and inhibitor was reduced in mutant cells compared to control cells, suggesting decreased autophagic flux. TEM showed the accumulation of large vacuoles in mutant cells with a decrease of autophagosomes. Our study demonstrated that the WDR45 mutation in this patient impaired autophagy and provided additional insight into ultrastructural changes of autophagic structures.

A case of CSF1R-related leukoencephalopathy: serial neuroimaging and neuropsychological tests.

Colony-stimulating factor 1 receptor (CSF1R)-related leukoencephalopathy is one of the most common causes of adult-onset leukodystrophy and is caused by mutation of the CSF1R gene. Brain magnetic resonance imaging (MRI) findings in asymptomatic patients have not been well recognized. We report on the case of a patient with CSF1R-related leukoencephalopathy who had a novel missense variant of the CSF1R gene with a family history of early onset dementia. This is a representative case of CSF1R-related leukoencephalopathy, which shows the progression of brain MRI and cognitive decline from an asymptomatic state.

Comparison of Amyloid in Cerebrospinal Fluid, Brain Imaging, and Autopsy in a Case of Progressive Supranuclear Palsy.

Cerebrospinal fluid (CSF) amyloid-beta 1-42 (Aß1-42) and amyloid positron emission tomography (PET) are the 2 main Alzheimer disease amyloid biomarkers that have been validated in neuropathologically confirmed Alzheimer disease cases. Although many studies have shown concordance of amyloid positivity or negativity between CSF Aß1-42 and amyloid PET, several studies also reported discrepancies between these 2 Aß biomarkers. We conducted a comparison of CSF Aß1-42 level, amyloid PET, and autopsy findings in a case with progressive supranuclear palsy in which biomarker acquisition and postmortem pathologic examination were conducted almost at the same time. Our case with antemortem CSF Aß1-42 (+)/amyloid PET (-) who was pathologically confirmed with Aß pathology in the cerebral cortex may indicate CSF Aß1-42 is more sensitive for assessing in vivo Aß than amyloid PET.

Atypical clinical manifestations of Miller Fisher syndrome.

Miller Fisher syndrome (MFS) is characterized by a clinical triad of ophthalmoplegia, ataxia, and areflexia, and is closely associated with serum anti-GQ1b antibody. Although the clinical triad is the cardinal diagnostic clue, a variety of other symptoms and signs beyond the triad have been reported. To elucidate the frequency and characteristics of atypical clinical manifestations of MFS, we recruited 38 patients with MFS and evaluated the symptoms or signs beyond the classic triad. Eleven (29%) of 38 patients had atypical clinical manifestations of MFS such as headache (n = 6), delayed facial palsy (n = 3), divergence insufficiency (n = 2), and taste impairment (n = 2). Headache was localized to the periorbital (n = 3), temporal (n = 2), or whole (n = 1) area. Only one of them showed bilateral papilledema and an elevated opening pressure in cerebrospinal fluid analysis. Delayed facial palsy developed after the other signs have reached nadir (n = 1) or started to improve (n = 2), and did not follow a pattern of descending paralysis with other cranial neuropathies. Two patients showed divergence insufficiency without external ophthalmoplegia, and another two had taste impairment over the entire tongue without the other signs of facial and glossopharyngeal nerve involvements. Our study shows that approximately 30% of MFS patients can have atypical clinical manifestations beyond the classic triad. These results reflect the broad clinical spectrum of MFS, and might be associated with the presence of additional antiganglioside antibodies besides anti-GQ1b in patients with MFS.

Genomic removal of a therapeutic mini-dystrophin gene from adult mice elicits a Duchenne muscular dystrophy-like phenotype.

Duchenne muscular dystrophy (DMD) is caused by dystrophin deficiency. A fundamental question in DMD pathogenesis and dystrophin gene therapy is whether muscle health depends on continuous dystrophin expression throughout the life. Published data suggest that transient dystrophin expression in early life might offer permanent protection. To study the consequences of adulthood dystrophin loss, we generated two strains of floxed mini-dystrophin transgenic mice on the dystrophin-null background. Muscle diseases were prevented in skeletal muscle of the YL238 strain and the heart of the SJ13 strain by selective expression of a therapeutic mini-dystrophin gene in skeletal muscle and heart, respectively. The mini-dystrophin gene was removed from the tibialis anterior (TA) muscle of 8-month-old YL238 mice and the heart of 7-month-old SJ13 mice using an adeno-associated virus serotype-9 Cre recombinase vector (AAV.CBA.Cre). At 12 and 15 months after AAV.CBA.Cre injection, mini-dystrophin expression was reduced by ∼87% in the TA muscle of YL238 mice and ∼64% in the heart of SJ13 mice. Mini-dystrophin reduction caused muscle atrophy, degeneration and force loss in the TA muscle of YL238 mice and significantly compromised left ventricular hemodynamics in SJ13 mice. Our results suggest that persistent dystrophin expression is essential for continuous muscle and heart protection.

Characterization of congenital myopathies at a Korean neuromuscular center.

INTRODUCTION: Congenital myopathies are muscle diseases characterized by specific histopathologic features, generalized hypotonia from birth, and perinatal complications, although some cases develop during childhood or, rarely, in adulthood. We undertook this study to characterize congenital myopathies among patients registered at our institution. METHODS: Clinical, histopathologic, and genetic features were evaluated in 34 patients recruited for this study. RESULTS: The majority of patients experienced a childhood onset, and no disease-related mortality was recorded during follow-up. Functional outcomes were no better for those with late-onset disease, indicating later disease progression can be significant. Nemaline myopathy was the most frequent pathology, followed by central core disease and centronuclear myopathy. Among the 18 (54.5%) genetically confirmed patients, NEB and RYR1 mutations were the most common, followed by DNM2 mutations. DISCUSSION: This study shows features not previously reported and suggests that congenital myopathy should be considered an important issue among adult patients. Muscle Nerve 58: 235-244, 2018.

Early stage memory impairment, visual hallucinations, and myoclonus combined with temporal lobe atrophy predict Alzheimer's disease pathology in corticobasal syndrome.

Corticobasal syndrome (CBS) is a typical phenotype of corticobasal degeneration (CBD). However, autopsy series have shown that many CBS cases emerge from various types of non-CBD pathology. We report a 73-year-old Korean man who was clinically diagnosed with CBS whose underlying pathology was Alzheimer's disease (AD) at autopsy (CBS-AD). This case suggests that early developing memory impairment and myoclonus, severe temporoparietal atrophy, and visual hallucinations may support a more specific prediction of CBS-AD.

Safe and bodywide muscle transduction in young adult Duchenne muscular dystrophy dogs with adeno-associated virus.

The ultimate goal of muscular dystrophy gene therapy is to treat all muscles in the body. Global gene delivery was demonstrated in dystrophic mice more than a decade ago using adeno-associated virus (AAV). However, translation to affected large mammals has been challenging. The only reported attempt was performed in newborn Duchenne muscular dystrophy (DMD) dogs. Unfortunately, AAV injection resulted in growth delay, muscle atrophy and contracture. Here we report safe and bodywide AAV delivery in juvenile DMD dogs. Three ∼2-m-old affected dogs received intravenous injection of a tyrosine-engineered AAV-9 reporter or micro-dystrophin (µDys) vector at the doses of 1.92-6.24 × 10(14) viral genome particles/kg under transient or sustained immune suppression. DMD dogs tolerated injection well and their growth was not altered. Hematology and blood biochemistry were unremarkable. No adverse reactions were observed. Widespread muscle transduction was seen in skeletal muscle, the diaphragm and heart for at least 4 months (the end of the study). Nominal expression was detected in internal organs. Improvement in muscle histology was observed in µDys-treated dogs. In summary, systemic AAV gene transfer is safe and efficient in young adult dystrophic large mammals. This may translate to bodywide gene therapy in pediatric patients in the future.

Late-onset episodic ataxia associated with SLC1A3 mutation.

Episodic ataxia type 6 (EA6) is caused by mutations in SLC1A3 that encodes excitatory amino acid transporter 1 (EAAT1), a glial glutamate transporter. EAAT1 regulates the extent and durations of glutamate-mediated signal by the clearance of glutamate after synaptic release. In addition, EAAT1 also has an anion channel activity that prevents additional glutamate release. We identified a missense mutation in SLC1A3 in a family with EA. The proband exhibited typical EA2-like symptoms such as recurrent ataxia, slurred speech with a duration of several hours, interictal nystagmus and response to acetazolamide, but had late-onset age of sixth decade. Whole-exome sequencing detected a heterozygous c.1177G>A mutation in SLC1A3. This mutation predicted a substitution of isoleucine for a highly conserved valine residue in the seventh transmembrane domain of EAAT1. The mutation was not present in 100 controls, a large panel of in-house genome data and various mutation databases. Most functional prediction scores revealed to be deleterious. Same heterozygous mutation was identified in one clinically affected family member and two asymptomatic members. Our data expand the mutation spectrum of SLC1A3 and the clinical phenotype of EA6.

Electrophysiological characteristics of R47W and A298T mutations in CLC-1 of myotonia congenita patients and evaluation of clinical features.

Myotonia congenita (MC) is a genetic disease that displays impaired relaxation of skeletal muscle and muscle hypertrophy. This disease is mainly caused by mutations of CLCN1 that encodes human skeletal muscle chloride channel (CLC-1). CLC-1 is a voltage gated chloride channel that activates upon depolarizing potentials and play a major role in stabilization of resting membrane potentials in skeletal muscle. In this study, we report 4 unrelated Korean patients diagnosed with myotonia congenita and their clinical features. Sequence analysis of all coding regions of the patients was performed and mutation, R47W and A298T, was commonly identified. The patients commonly displayed transient muscle weakness and only one patient was diagnosed with autosomal dominant type of myotonia congenita. To investigate the pathological role of the mutation, electrophysiological analysis was also performed in HEK 293 cells transiently expressing homo- or heterodimeric mutant channels. The mutant channels displayed reduced chloride current density and altered channel gating. However, the effect of A298T on channel gating was reduced with the presence of R47W in the same allele. This analysis suggests that impaired CLC-1 channel function can cause myotonia congenita and that R47W has a protective effect on A298T in relation to channel gating. Our results provide clinical features of Korean myotonia congenita patients who have the heterozygous mutation and reveal underlying pathophyological consequences of the mutants by taking electrophysiological approach.

NEB-related core-rod myopathy with distinct clinical and pathological features.

INTRODUCTION: Mutations in the gene encoding nebulin (NEB) are known to cause several types of congenital myopathy including recessive nemaline myopathy and distal nebulin myopathy. Core-rod myopathy has recently been reported to be another type of NEB-related myopathy, and is pathologically characterized by the coexistence of cores and nemaline rods within muscle fibers. METHODS: We describe 2 patients with core-rod myopathy who were analyzed genetically by whole exome sequencing and evaluated clinically and pathologically. Findings were compared with those of patients with the disease of other genetic causes. RESULTS: Three NEB mutations were identified, 2 of which were novel. Mild clinical features, unusual patterns of muscle involvement, and atypical pathological findings were observed. CONCLUSIONS: We propose that the clinical and pathological spectrum of core-rod myopathy should be widened. A significant amount of residual nebulin expression is believed to contribute to the much milder phenotype exhibited by the patients we describe here.

Effect of enzyme replacement therapy in late onset Pompe disease: open pilot study of 48 weeks follow-up.

Late-onset Pompe disease (LOPD) is an autosomal recessive disorder caused by deficiency of the enzyme acid glucosidase alfa (GAA). Recently, enzyme replacement therapy (ERT) using recombinant human GAA (rhGAA) became clinically available, and is expected to modify the clinical course in LOPD of various stages. In this study, we evaluated the efficacy and adverse events of ERT for 48 weeks in Korean LOPD patients. Five Korean LOPD patients were included in the study. At baseline, clinical and laboratory features, including muscular and pulmonary function, were assessed, and rhGAA was infused every 2 weeks. Then, patients were examined at every 12-week interval for evaluation of changes in motor and pulmonary function for 48 weeks along with adverse reactions to ERT. The muscular and pulmonary function of the patients varied depending on the baseline condition of the patient after 48 weeks of ERT. However, the overall function of the patients showed stabilization of the disease rather than the improvement seen in infantile-onset Pompe disease. This is the first clinical study on ERT of Korean LOPD patients. Results of our study showed stabilization of muscular and pulmonary function in LOPD patients for 48 weeks with a favorable prognosis for patients who received early diagnosis and ambulatory patients. One of our patients developed a serious anaphylactic reaction, which necessitated the cessation of further ERT. Therefore, our study shows that early diagnosis and ERT are important in preventing further deterioration of the disease.

Exercise-induced downbeat nystagmus in a Korean family with a nonsense mutation in CACNA1A.

Episodic ataxia type 2 (EA2) is characterized by recurrent attacks of vertigo and ataxia lasting hours triggered by emotional stress or exercise. Although interictal horizontal gaze-evoked nystagmus and rebound nystagmus are commonly observed in patients with EA2, the nystagmus has been rarely reported during the vertigo attack. To better describe exercise-induced nystagmus in EA2, four affected members from three generations of a Korean family with EA2 received full neurological and neuro-otological evaluations. Vertigo was provoked in the proband with running for 10 min to record eye movements during the vertigo attack. We performed a polymerase chain reaction-based direct sequence analysis of all coding regions of CACNA1A in all participants. The four affected members had a history of exertional vertigo, imbalance, childhood epilepsy, headache, and paresthesia. The provocation induced severe vertigo and imbalance lasting several hours, and oculography documented pure downbeat nystagmus during the attack. Genetic analyses identified a nonsense mutation in exon 23 which has been registered in dbSNP as a pathogenic allele (c.3832C>T, p.R1278X) in all the affected members. Ictal downbeat nystagmus in the studied family indicates cerebellar dysfunction during the vertigo attack in EA2. In patients with episodic vertigo and ataxia, the observation of exercise-induced nystagmus would provide a clue for EA2.