Krebs von den Lungen 6 decreased in the serum and muscle of GNE myopathy patients

UDP‐N‐acetylglucosamine 2‐epimerase/N‐acetylmannosamine kinase (GNE) is necessary for sialic acid biosynthesis. GNE myopathy is caused by a defect in GNE, and hyposialylation is a key factor in the pathomechanism of GNE myopathy. Although candidates for evaluating hyposialylation have been reported, it is difficult to measure them in routine clinical practice. Sialylation is necessary for synthesis of various glycoproteins, including Krebs von den Lungen‐6 (KL‐6)/mucin 1 (MUC1). Here we report that KL‐6/MUC1 is decreased in GNE myopathy. We observed that KL‐6 levels were decreased in the serum of patients with GNE myopathy, and that KL‐6 and MUC1‐C were also decreased in muscle biopsy specimens from these patients. An immunofluorescent study revealed that KL‐6 and MUC1‐C were not present in the sarcolemma but were, instead, localized in rimmed vacuoles in specimens from patients with GNE myopathy. KL‐6 is already used to detect lung diseases in clinical practice, and this glycoprotein may be a novel candidate for evaluating hyposialylation in GNE myopathy.

Anti-HMGCR Antibody-Positive Myopathy Shows Bcl-2-Positive Inflammation and Lymphocytic Accumulations

Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) and antisignal recognition particle (SRP) antibodies are frequently associated with immune-mediated necrotizing myopathy (IMNM). However, the difference in clinical manifestations between anti-HMGCR and anti-SRP antibodies is unclear. HMGCR is an essential enzyme for cholesterol biosynthesis and is inhibited by statins that regulate apoptosis of Bcl-2-positive and beta chemokine receptor 4 (CCR4)-positive lymphoma cells. In this study, we aimed to clarify Bcl-2 and CCR4 expressions of lymphocytes in anti-HMGCR antibody-positive IMNM and explore the difference between anti-HMGCR antibody-positive myopathy and other inflammatory myopathies. We retrospectively examined Bcl-2- and CCR4-positive lymphocyte infiltrations in muscle and skin biopsy specimens from 19 anti-HMGCR antibody-positive patients and 75 other idiopathic inflammatory myopathies (IIMs) patients. A higher incidence of Bcl-2- and CCR4-positive lymphocytes was detected in the muscle and skin of anti-HMGCR antibody-positive IMNM patients (p < 0.001). In 5 patients with anti-HMGCR antibodies, Bcl-2-positive lymphocytes formed lymphocytic accumulations, which were not observed in other IIMs. Low-density lipoprotein cholesterol levels were not increased except for patients with Bcl-2-positive lymphocytic accumulations (p = 0.010). Bcl-2 and CCR4 lymphocyte infiltrations could be a pathological characteristic of anti-HMGCR antibody-positive IMNM.

Chronic kidney disease caused by maternally inherited diabetes and deafness: a case report

Maternally inherited diabetes and deafness (MIDD) is a mitochondrial genetic disorder with variable clinical presentations, which can delay its diagnosis. Herein, we report the case of a 57-year-old Japanese man with MIDD who developed chronic kidney disease. He developed proteinuria long before his diabetes and deafness; at the age of 36 years, a renal biopsy showed minor glomerular abnormality and electron microscopy showed mild mitochondrial degeneration in the distal tubular epithelial cells. Twenty years later, a second renal biopsy showed nephrosclerosis with interstitial fibrosis and arteriolar hyaline thickening, despite the absence of hypertension and relatively good glycemic control. Granular swollen epithelial cells were found in the medullary collecting duct epithelium. Electron microscopy showed accumulating mitochondria in podocytes and tubular cells, leading to the diagnosis of MIDD. A muscle biopsy also showed ragged-red fibers, despite the absence of muscle weakness. Mitochondrial DNA analysis revealed an m.3243A > G mutation, and taurine supplementation was initiated. Our findings suggest that mitochondrial dysfunction is mainly associated with progressive renal damage.

The first Japanese case of primary familial brain calcification caused by an MYORG variant

Primary familial brain calcification (PFBC) is a hereditary neurological disorder characterized by idiopathic calcification of the bilateral basal ganglia and other areas of the brain. MYORG has been identified as the first causative gene of autosomal recessive PFBC in Chinese families. There have been several reports of PFBC associated with MYORG (MYORG-PFBC) in individuals of Middle Eastern, European, and Latin American ancestry but to date, there have been no reported Japanese cases. We report the first Japanese case of MYORG-PFBC. The patient was a 43-year-old Japanese woman who experienced mild headaches and cerebellar ataxia including dysarthria. Computed tomography showed calcification in the cerebral white matter, basal ganglia, cerebellum, and brainstem. Using exome sequencing, we identified a homozygous variant in the MYORG gene (NM_020702.4: c.794C>T,p.Thr265Met). Our patient presented dysarthria and extensive calcification affecting the pons, which are specific features of MYORG-PFBC. We report clinical symptoms and imaging findings of a case with p.Thr265Met variant.

Middle-age-onset cerebellar ataxia caused by a homozygous TWNK variant: a case report

Background

The TWNK gene encodes the twinkle protein, which is a mitochondrial helicase for DNA replication. The dominant TWNK variants cause progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3, while the recessive variants cause mitochondrial DNA depletion syndrome 7 and Perrault syndrome 5. Perrault syndrome is characterized by sensorineural hearing loss in both males and females and gonadal dysfunction in females. Patients with Perrault syndrome may present early-onset cerebellar ataxia, whereas middle-age-onset cerebellar ataxia caused by TWNK variants is rare.

Case presentation

A Japanese female born to consanguineous parents presented hearing loss at age 48, a staggering gait at age 53, and numbness in her distal extremities at age 57. Neurological examination revealed sensorineural hearing loss, cerebellar ataxia, decreased deep tendon reflexes, and sensory disturbance in the distal extremities. Laboratory tests showed no abnormal findings other than a moderate elevation of pyruvate concentration levels. Brain magnetic resonance imaging revealed mild cerebellar atrophy. Using exome sequencing, we identified a homozygous TWNK variant (NM_021830: c.1358G>A, p.R453Q).

Conclusions

TWNK variants could cause middle-age-onset cerebellar ataxia. Screening for TWNK variants should be considered in cases of cerebellar ataxia associated with deafness and/or peripheral neuropathy, even if the onset is not early.

Biallelic mutation of HSD17B4 induces middle age-onset spinocerebellar ataxia

Objective

To determine the genetic underpinnings of slowly progressive spinocerebellar ataxia, autosomal recessive (SCAR), we performed exome analysis and examined the relationship between clinical severity and functional change induced by the mutation.

Methods

Homozygosity fingerprinting and exome sequencing were performed to identify causative mutations in 2 consanguineous families. We assessed the expression of D-bifunctional protein (DBP) and the amount of dimerized DBP in fibroblasts by immunoblot and quantitative reverse transcription PCR. The pathogenicity of the mutation was evaluated using the Combined Annotation-Dependent Depletion (CADD) scores; these results were compared with the scores of previously reported mutations.

Results

We identified a homozygous mutation as causative of middle age–onset SCAR: p.Ala175Thr, which is located in HSD17B4 that encodes peroxisomal DBP. The patients developed cerebellar ataxia, and the subsequent progression was slow. The symptoms presented were milder than those in previously reported cases. The messenger RNA expression levels were normal, but protein levels were diminished. Dimerization of DBP was also reduced. The CADD score of the identified mutation was lower than those of previously reported mutations.

Conclusions

This is the report of middle age–onset DBP deficiency. Residual functional DBP caused relatively mild symptoms in the affected patients, i.e., slowly progressive ataxia and hearing loss. This study broadens the scope of DBP deficiency phenotypes and indicates that CADD scores may be used to estimate the severity of DBP deficiencies.

Genetic screening for potassium channel mutations in Japanese autosomal dominant spinocerebellar ataxia

Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease characterized by cerebellar ataxia. Many causative genes have been identified to date, the most common etiology being the abnormal expansion of repeat sequences, and the mutation of ion channel genes also play an important role in the development of SCA. Some of them encode calcium and potassium channels. However, due to limited reports about potassium genes in SCA, we screened 192 Japanese individuals with dominantly inherited SCA who had no abnormal repeat expansions of causative genes for potassium channel mutations (KCNC3 for SCA13 and KCND3 for SCA19/SCA22) by target sequencing. As a result, two variants were identified from two patients: c.1973G>A, p.R658Q and c.1018G>A, p.V340M for KCNC3, and no pathogenic variant was identified for KCND3. The newly identified p.V340M exists in the extracellular domain, and p.R658Q exists in the intracellular domain on the C-terminal side, although most of the reported KCNC3 mutations are present at the transmembrane site. Adult-onset and slowly progressive cerebellar ataxia are the main clinical features of SCA13 and SCA19 caused by potassium channel mutations, which was similar in our cases. SCA13 caused by KCNC3 mutations may present with deep sensory loss and cognitive impairment in addition to cerebellar ataxia. In this study, mild deep sensory loss was observed in one case. SCA caused by potassium channel gene mutations is extremely rare, and more cases should be accumulated in the future to elucidate its pathogenesis due to channel dysfunction.

Synphilin-1 has neuroprotective effects on MPP+-induced Parkinson's disease model cells by inhibiting ROS production and apoptosis

Synphilin-1, a cytoplasmic protein, interacts with α-synuclein which is one of the main constituents of Lewy bodies and plays an important role in the pathology of Parkinson's disease (PD), in neurons. This interaction indicates that synphilin-1 may also play a central role in PD. However, the biological functions of synphilin-1 are not fully understood, and whether synphilin-1 is neurotoxic or neuroprotective remains controversial. This study examined the function of synphilin-1 in a PD model in vitro. We used an inhibitor of mitochondrial complex I, 1-methyl-4-phenylpyridinium (MPP⁺). We established human neuroblastoma SH-SY5Y cell lines that stably expressed human synphilin-1. We found that overexpression of synphilin-1 increased SH-SY5Y cell viability after MPP⁺ treatment. We further found that synphilin-1 significantly suppressed apoptotic changes in nuclei, including nuclear condensation and fragmentation, after MPP⁺ treatment. We showed that synphilin-1 significantly decreased MPP⁺-induced cleaved caspase-3 and cleaved poly-ADP-ribose polymerase levels by using western blotting. Production of reactive oxygen species (ROS) induced by MPP⁺ was significantly reduced in cells expressing synphilin-1 compared to those expressing empty vector. Synphilin-1 inhibited MPP⁺-induced cytochrome c release from mitochondria into the cytosol. These data suggested that synphilin-1 may function to protect against dopaminergic cell death by preserving mitochondrial function and inhibiting early steps in the intrinsic apoptotic pathway. Taken together, our results indicated that synphilin-1 may play neuroprotective roles in PD pathogenesis by inhibiting ROS production and apoptosis.

Muscle-dominant wild-type TDP-43 expression induces myopathological changes featuring tubular aggregates and TDP-43-positive inclusions

Muscle histology of sporadic inclusion body myositis (sIBM) demonstrates inflammatory findings and degenerative features including accumulation of TAR DNA-binding protein of 43 kDa (TDP-43). However, whether sarcoplasmic accumulation of TDP-43 is a primary trigger of muscle degeneration or a secondary event resulting from muscle degeneration in the pathophysiology of sIBM remained unclear. Our study aimed to discover whether muscle-dominant expression of TDP-43 is a primary cause of muscle degeneration. We generated several lines of wild-type TDP-43 transgenic mice driven by a creatine kinase 8 promoter, and analyzed the phenotypes via biochemical, histological, and proteomic techniques. The mice showed increased serum levels of myogenic enzymes. Muscle histology demonstrated myopathic changes including fiber size variation, abundant tubular aggregates, and TDP-43 aggregation with upregulation of endoplasmic reticulum (ER) stress. Proteomic analysis with aggregated materials in degenerative myofibers identified increased sarcoplasmic reticulum (SR)/ER-resident proteins that regulated calcium homeostasis, as well as cytosolic 5'-nucleotidase 1A. Muscle-dominant wild-type TDP-43 expression indeed caused myotoxicity featuring tubular aggregates and TDP-43-positive inclusions. Our observation suggested that TDP-43 aggregates might not be sufficient to trigger the pathogenesis of sIBM although myofiber sarcoplasmic aggregation of TDP-43 led to myofiber degeneration via ER stress and possibly calcium dysregulation, independently of inflammatory process.

Muscle weakness as a presenting symptom in ANCA-associated vasculitis

Muscle weakness is rarely a presenting symptom of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), although the disease frequently involves the lungs, skin, neurons, and kidneys. Here we describe a case of AAV presenting with muscle weakness in which only muscle biopsy could confirm the diagnosis. The literature review, including three similar cases, suggested that patients with ANCA-associated muscle vasculitis likely had myalgia, normal levels of creatine kinase, pulmonary fibrosis, rheumatoid factor, and muscle edema on MRI.

[Adult-Onset Neuronal Intranuclear Inclusion Disease in Two Female Siblings]

Neuronal intranuclear inclusion disease (NIID) in two adult siblings (both women, aged 76 and 68 years) is reported on here. The elder sister had a resting tremor and bradykinesia at age 66 years, and treatment with L-DOPA was initiated(L-3, 4-dihydroxyphenylalanine). Three years later, she showed a frozen gait that was associated with the medication wearing off. The clinical manifestations did not improve with the administration of antiparkinson drugs. Six years later, she showed impaired cognitive functions, which had occured gradually, and she began to take donepezil. At age 76, she was diagnosed with NIID based on a skin biopsy. The younger sister exhibited peculiar behaviors at age 62 years, and showed impaired cognitive function 4 years later. At age 68 years, she died because of an accident in the bath tub. In both cases, diffusion-weighted magnetic resonance imaging (DWI) showed high-intensity signals in the U fiber area of the corticomedullary junction. These signals began in the frontal lobe at the initial stages of the disease, and extended to the parietal and temporal lobes at later stages. High-intensity signal areas were detected in the deep white matter in T2-weighted and fluid-attenuated inversion recovery (FLAIR) images in the elder sister. The histological examination via a skin biopsy was useful in diagnosing NIID. (Received August 18, 2016; Accepted December 8, 2016; Published March 1, 2017).

Clinicopathological features of adult-onset neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease (NIID) is a slowly progressive neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in the central and peripheral nervous system, and also in the visceral organs. NIID has been considered to be a heterogeneous disease because of the highly variable clinical manifestations, and ante-mortem diagnosis has been difficult. However, since we reported the usefulness of skin biopsy for the diagnosis of NIID, the number of NIID diagnoses has increased, in particular adult-onset NIID. In this study, we studied 57 cases of adult-onset NIID and described their clinical and pathological features. We analysed both NIID cases diagnosed by post-mortem dissection and by ante-mortem skin biopsy based on the presence of characteristic eosinophilic, hyaline and ubiquitin-positive intanuclear inclusion: 38 sporadic cases and 19 familial cases, from six families. In the sporadic NIID cases with onset age from 51 to 76, dementia was the most prominent initial symptom (94.7%) as designated 'dementia dominant group', followed by miosis, ataxia and unconsciousness. Muscle weakness and sensory disturbance were also observed. It was observed that, in familial NIID cases with onset age less than 40 years, muscle weakness was seen most frequently (100%), as designated 'limb weakness group', followed by sensory disturbance, miosis, bladder dysfunction, and dementia. In familial cases with more than 40 years of onset age, dementia was most prominent (100%). Elevated cerebrospinal fluid protein and abnormal nerve conduction were frequently observed in both sporadic and familial NIID cases. Head magnetic resonance imaging showed high intensity signal in corticomedullary junction in diffusion-weighted image in both sporadic and familial NIID cases, a strong clue to the diagnosis. All of the dementia dominant cases presented with this type of leukoencephalopathy on head magnetic resonance imaging. Both sporadic and familial NIID cases presented with a decline in Mini-Mental State Examination and Frontal Assessment Battery scores. Based on these clinicopathological features, we proposed a diagnosis flow chart of adult-onset NIID. Our study suggested that the prevalence rate of adult-onset NIID may be higher than previously thought, and that NIID may be underdiagnosed. We should take NIID into account for differential diagnosis of leukoencephalopathy and neuropathy.

Deviation in the recovery of the lower limb and respiratory muscles of patients with polymyositis: a preliminary clinical study

[Purpose] The purposes of this study were to quantify the serial changes in lower limb and respiratory muscle strengths and to evaluate the acute effects of physiotherapy in polymyositis patients. [Subjects and Methods] Five patients (57.6 ± 9.0 years, 50 to 72; four females) received physiotherapy five days a week for four weeks. The lower limb and respiratory muscle strength, the % vital capacity, and the Barthel index were evaluated at baseline and after the intervention. [Results] The patient’s symptoms and creatine kinase values did not change, and after four weeks, all of the patients exhibited significantly increased outcomes compared with the baseline. However, the inspiratory muscle strength of the patients presented smaller improvements than the expiratory muscle strength. [Conclusion] Differential changes in inspiratory and expiratory muscle strength were observed following physiotherapy, and an unbalanced muscle distribution may explain the pathological and therapeutic effects.

Prevalences of Peripheral Arterial Disease Diagnosed by Computed Tomography Angiography in Patients with Acute Ischemic Stroke

BACKGROUND

Few studies have examined the prevalence of peripheral arterial disease (PAD) with the use of computed tomography angiography (CTA) in patients with acute ischemic stroke (AIS), although several reports have examined its prevalence using an ankle brachial index (ABI). We aimed to determine the prevalence of PAD indicated by CTA in patients with AIS and to clarify the prevalence of PAD in each clinical ischemic stroke subtype.

METHODS

We included 199 consecutive patients with AIS admitted to our hospital and divided them into PAD and non-PAD groups according to the CTA findings.

RESULTS

Of the 199 patients, 40 (20.1%) had PAD; 27 (67.5%) of the PAD patients were asymptomatic. The prevalence of abnormal ABI (≤.9) was 12.2%. Patients with PAD were older (78.3 ± 10.2 versus 71.5 ± 10.9, P <.001) and had a significantly lower ABI value (.89 ± .24 versus 1.15 ± .09, P <.001) and higher prevalence of diabetes mellitus (50.0% versus 31.4%, P = .028), atrial fibrillation (40.0% versus 16.4%, P = .001), coronary artery disease (32.5% versus 8.2%, P <.001), and intracranial arterial stenosis (47.5% versus 28.9%, P = .025) than patients without PAD. The prevalence of cerebral microbleeds was not different between patients with PAD and those without PAD (25.6% versus 25.4%, P = .985). The prevalence of PAD among ischemic stroke subtypes was highest in patients with cardioembolic infarction (40.5%).

CONCLUSIONS

Almost one fourth of the AIS patients examined had PAD on CTA. Cardioembolic infarction patients showed the highest prevalence of PAD among the clinical ischemic subtypes, suggesting the coexistence of atheromatous diseases and atrial fibrillation.