Anti-mitochondrial M2 antibody-positive myositis may be an independent subtype of autoimmune myositis.

It is still unknown whether anti-mitochondrial M2 antibody (AM2A)-positive myositis is an independent subtype of autoimmune myositis (AIM). As such, the aim of this study is to better characterize the clinicopathological features in a large cohort of patients. This study utilized the muscle biopsy samples from AM2A-positive patients, which were sent to the National Center of Neurology and Psychiatry for diagnostic purposes from January 2008 to December 2020.

Retrotrans-genomics identifies aberrant THE1B endogenous retrovirus fusion transcripts in the pathogenesis of sarcoidosis.

Transposon-like human element 1B (THE1B) originates from ancient retroviral sequences integrated into the primate genome approximately 50 million years ago, now accounting for at least 27,233 copies in the human genome, suggesting their extensive influence on human genomic architecture. Here we report identification of 19 THE1B fusion transcripts through short- and long-read RNA-seq analysis, 15 of which are previously unmapped, showing elevated expression in 16 individuals with sarcoid myopathy (SM), as compared to 400 controls with various other muscle diseases. Analysis of publicly available RNA-seq data indicated a correlation between the reduced expression of eight THE1B fusion transcripts and clinical improvement in individuals with cutaneous sarcoidosis receiving tofacitinib treatment.

Tumefactive demyelinating lesions: a retrospective cohort study in Thailand.

Tumefactive demyelinating lesions (TDL), characterized by large (≥ 2 cm) demyelinating lesions mimicking tumors, are a rare manifestation of the central nervous system inflammatory demyelinating diseases (CNS-IDD). Distinguishing TDL from other brain lesions can be challenging, often necessitating biopsy or advanced diagnostics. The natural history of TDL varies among races.

Exploiting nanopore sequencing for characterization and grading of IDH-mutant gliomas.

The 2021 WHO Classification of Central Nervous System Tumors recommended evaluation of cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) deletion in addition to codeletion of 1p/19q to characterize IDH-mutant gliomas. Here, we demonstrated the use of a nanopore-based copy-number variation sequencing (nCNV-seq) approach to simultaneously identify deletions of CDKN2A/B and 1p/19q. The nCNV-seq approach was initially evaluated on three distinct glioma cell lines and then applied to 19 IDH-mutant gliomas (8 astrocytomas and 11 oligodendrogliomas) from patients.

Association Between HLA Alleles and Autoantibodies in Dermatomyositis Defined by Sarcoplasmic Expression of Myxovirus Resistance Protein A.

Objective: The diagnosis in the studies analyzing HLA of dermatomyositis (DM) was based on a combined clinical category of polymyositis/DM. This retrospective study investigated the associations of HLA with 5 DM-specific autoantibodies in Japanese patients diagnosed by muscle pathology.

Methods: We diagnosed Japanese patients with DM based on sarcoplasmic expression of myxovirus resistance protein A.

Muscle pathology of antisynthetase syndrome according to antibody subtypes.

Identification of antisynthetase syndrome (ASS) could be challenging due to inaccessibility and technical difficulty of the serology test for the less common non-Jo-1 antibodies. This study aimed to describe ASS antibody-specific myopathology and evaluate the diagnostic utility of myofiber HLA-DR expression. We reviewed 212 ASS muscle biopsies and compared myopathologic features among subtypes.

Update on dermatomyositis.

Purpose Of Review: This review summarizes and comments on current knowledge in dermatomyositis.

Recent Findings: The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis.

Reliability of antinuclear matrix protein 2 antibody assays in idiopathic inflammatory myopathies is dependent on target protein properties.

A line blotting assay (LB) is currently used to detect myositis-specific autoantibodies (MSAs) in patients with idiopathic inflammatory myopathies (IIMs), because of its simplicity; however, the sensitivity and specificity of this assay is low. The aim of this study is to evaluate the accuracy of the commercial LB in detection of antinuclear matrix protein 2 (NXP2) antibody. Seventy-seven serum samples from patients with IIMs, in which anti-NXP2 antibodies were detected through immunoprecipitation and western blotting (IP-WB) using K562 cell lysate, were enrolled.

Dermatomyositis: Muscle Pathology According to Antibody Subtypes.

Background And Objectives: Discoveries of dermatomyositis-specific antibodies (DMSAs) in patients with dermatomyositis raised awareness of various myopathologic features among antibody subtypes. However, only perifascicular atrophy and perifascicular myxovirus resistant protein A (MxA) overexpression were officially included as definitive pathologic criteria for dermatomyositis classification. We aimed to demonstrate myopathologic features in MxA-positive dermatomyositis to determine characteristic myopathologic features in different DMSA subtypes.

Deep convolutional neural network-based algorithm for muscle biopsy diagnosis.

Histopathologic evaluation of muscle biopsy samples is essential for classifying and diagnosing muscle diseases. However, the numbers of experienced specialists and pathologists are limited. Although new technologies such as artificial intelligence are expected to improve medical reach, their use with rare diseases, such as muscle diseases, is challenging because of the limited availability of training datasets.

Anti-nuclear matrix protein 2 antibody-positive inflammatory myopathies represent extensive myositis without dermatomyositis-specific rash.

Objectives: Myositis-specific autoantibodies (MSAs) define distinct clinical subsets of idiopathic inflammatory myopathies (IIMs). The anti-nuclear matrix protein 2 (NXP2) antibody, a MSA detected in juvenile/adult IIMs, has been reported to be associated with a high risk of subcutaneous calcinosis, subcutaneous oedema and internal malignancies. The study aimed to clarify the clinical features of anti-NXP2 antibody-positive IIMs in detail.

Inflammatory features in sporadic late-onset nemaline myopathy are independent from monoclonal gammopathy.

Sporadic late-onset nemaline myopathy (SLONM) is a rare adult-onset non-hereditary disease with subacute proximal muscle and often axial muscle weakness, characterized by the presence of nemaline bodies in skeletal muscle biopsies. Considering its association with concurrent monoclonal gammopathy of undetermined significance (MGUS), the disease is classified into two major subtypes (1) SLONM without MGUS (SLONM-noMGUS) and (2) with MGUS (SLONM-MGUS) association. SLONM associated with HIV infection (SLONM-HIV) is also reported.

Simplified approach for pathological diagnosis of diffuse gliomas in adult patients.

The most recent WHO classification (2016) for gliomas introduced integrated diagnoses requiring both phenotypic and genotypic data. This approach presents difficulties for countries with limited resources for laboratory testing. The present study describes a series of 118 adult Thai patients with diffuse gliomas, classified by the WHO 2016 classification.

Biallelic variants in LIG3 cause a novel mitochondrial neurogastrointestinal encephalomyopathy.

Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy.

Pathologic Features of Anti-Mi-2 Dermatomyositis.

Objective: To identify the characteristic pathologic features of dermatomyositis (DM) associated with anti-Mi-2 autoantibodies (anti-Mi-2 DM).

Methods: We reviewed 188 muscle biopsies from patients (1) pathologically diagnosed with DM through the sarcoplasmic expression for the myxovirus-resistant protein A and (2) serologically positive for 1 of 5 DM-specific autoantibodies (DMSAs) (anti-Mi-2, n = 30; other DMSAs, n = 152) or negative for all 5 DMSAs (n = 6). We then compared the histopathologic and immunohistochemical features of patients with anti-Mi-2 DM to those with non-Mi-2 DM and patients with anti-synthetase syndrome (ASS) (n = 212) using the test, Fisher exact test, and a logistic regression model.

Pathogenic Variants in the Myosin Chaperone UNC-45B Cause Progressive Myopathy with Eccentric Cores.

The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness.

A Cavernous Venous Malformation of the Orbit Mimicking an Idiopathic Orbital Inflammation.

Orbital cavernous venous malformations (CVMs) are usually slow progressing. Multiple CVMs, bilateral orbital CVMs, and acute presentations are rare. We present a rare, bilateral, orbital CVM with acute painful visual loss in the left eye.

Where are we moving in the classification of idiopathic inflammatory myopathies?

Purpose Of Review: Discoveries of myositis-specific antibodies, transcriptomic signatures, and clinicoseropathological correlation support classification of idiopathic inflammatory myopathies (IIM) into four major subgroups: dermatomyositis, immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM) whereas leaving polymyositis as a historical nonspecific diagnosis of exclusion. This review summarizes and comments on recent knowledge regarding the major subgroup of IIM.

Recent Findings: Type 1 interferon (IFN1) pathway activation is the most prominent in dermatomyositis whereas type 2 interferon (IFN2) pathway activation is high in IBM and ASS; neither pathway is distinct in IMNM.

HLA-DRB1 allele and autoantibody profiles in Japanese patients with inclusion body myositis.

Introduction: Inclusion body myositis (IBM) is an idiopathic inflammatory myopathy, characterized by unique clinical features including finger flexor and quadriceps muscle weakness and a lack of any reliable treatment. The human leukocyte antigen (HLA)-DRB1 allele and autoantibody profiles in Japanese IBM patients have not been fully elucidated.

Methods: We studied 83 Japanese IBM patients with a mean age of 69 years (49 males and 34 females) who participated in the 'Integrated Diagnosis Project for Inflammatory Myopathies' from January 2011 to September 2016.

Association of Dermatomyositis Sine Dermatitis With Anti-Nuclear Matrix Protein 2 Autoantibodies.

Importance: Reports on dermatomyositis (DM) sine dermatitis (DMSD) are scarce, and the concept of the disease has not been widely accepted.

Objective: To confirm the existence of DMSD, determine its prevalence, and characterize its serologic features.

Design, Setting, And Participants: This is a cohort study that reviewed clinical information, laboratory data, and muscle pathology slides from January 2009 to August 2019.