Heterozygous loss-of-function variants in SPTAN1 cause an early childhood onset distal myopathy.

Purpose: Heterozygous pathogenic variants in SPTAN1 cause a diverse spectrum of neurogenetic disorders ranging from peripheral and central nervous system involvement to complex syndromic presentations. We set out to investigate the role of SPTAN1 in genetically unsolved hereditary myopathies.

Methods: Through international collaboration we identified 14 families with distal weakness and heterozygous SPTAN1 loss-of-function variants.

Distinct whole-body muscle MRI imaging patterns in PAX7-congenital myopathy: A case report.

PAX7 is a myogenesis transcription factor important for satellite cell specification and function and thus involved in muscle growth, maintenance, repair and regeneration. Recently, a new autosomal recessive congenital myopathy was described that is caused by biallelic variants in . Our aim is to describe phenotype and whole-body muscle MRI with follow-up imaging findings in a patient with a novel homozygous missense variant in We also compare our patients' imaging features with a patient reported in the initial study, to identify a possible emerging pattern for PAX7-congenital myopathy.

Taking on the Titin: Muscle imaging as a diagnostic marker of biallelic related myopathy.

Background: The accurate diagnosis of titin-related myopathies (-RM) is challenging due to the "gigantism" of the coding gene with an incompletely understood landscape of normal genetic variation, an increasing number of pathogenic variants, and wide phenotypic variability of both cardiac and muscle involvement. Particularly in situations of potentially incomplete genotypes, clinicians need more phenotyping tools to help confidently determine the pathogenicity of variants in and accurately diagnose titinopathies.

Objective: To illustrate the pattern of muscle involvement found by muscle imaging in patients with RM.

Neurogenic arthrogryposis, hypotonia, dysmorphic features plus malformation of cortical development further expands the ARL6IP1 loss-of-function phenotype.

Biallelic variants in ARL6IP1 are associated with a rare, complicated form of progressive hereditary spastic paraplegia. Among the few cases reported thus far, two distinct phenotypic clusters with upper and lower motor neuron pathology and varying severities have emerged. Here, we describe a proband who presented with decreased fetal movements, intrauterine growth retardation, arthrogryposis multiplex congenita (AMC), dysmorphic features, weakness and hypotonia.

Clinical characterization of Collagen XII-related disease caused by biallelic COL12A1 variants.

Objective: While there have been several reports of patients with dominantly acting COL12A1 variants, few cases of the more severe recessive Collagen XII-related disorders have previously been documented.

Methods: We present detailed clinical, immunocytochemical, and imaging data on eight additional patients from seven families with biallelic pathogenic variants in COL12A1.

Results: All patients presented with a consistent constellation of congenital onset clinical features: hypotonia, dysmorphic features, most notably gingival hypertrophy, prominent distal joint hyperlaxity, with co-occurring contractures of large joints, and variable muscle involvement, evident both clinically and on muscle imaging.

Effects of HMG CoA reductase (HMGCR) deficiency on skeletal muscle development.

Pathogenic variants in HMGCR were recently linked to a limb-girdle muscular dystrophy (LGMD) phenotype. The protein product HMG CoA reductase (HMGCR) catalyzes a key component of the cholesterol synthesis pathway. The two other muscle diseases associated with HMGCR, statin-associated myopathy (SAM) and autoimmune anti-HMGCR myopathy, are not inherited in a Mendelian pattern.

Structural variation in nebulin and its implications on phenotype and inheritance: establishing a dominant distal phenotype caused by large deletions.

Introduction: Structural variants (SVs) of the nebulin gene (), including intragenic duplications, deletions, and copy number variation of the triplicate region, are an established cause of recessively inherited nemaline myopathies and related neuromuscular disorders. Large deletions have been shown to cause dominantly inherited distal myopathies. Here we provide an overview of 35 families with muscle disorders caused by such SVs in .

Mitochondrial DNA variant detection in over 6,500 rare disease families by the systematic analysis of exome and genome sequencing data resolves undiagnosed cases.

Background: Variants in the mitochondrial genome (mtDNA) cause a diverse collection of mitochondrial diseases and have extensive phenotypic overlap with Mendelian diseases encoded on the nuclear genome. The mtDNA is often not specifically evaluated in patients with suspected Mendelian disease, resulting in overlooked diagnostic variants.

Methods: Using dedicated pipelines to address the technical challenges posed by the mtDNA - circular genome, variant heteroplasmy, and nuclear misalignment - single nucleotide variants, small indels, and large mtDNA deletions were called from exome and genome sequencing data, in addition to RNA-sequencing when available.

Diagnosing missed cases of spinal muscular atrophy in genome, exome, and panel sequencing data sets.

Purpose: We set out to develop a publicly available tool that could accurately diagnose spinal muscular atrophy (SMA) in exome, genome, or panel sequencing data sets aligned to a GRCh37, GRCh38, or T2T reference genome.

Methods: The SMA Finder algorithm detects the most common genetic causes of SMA by evaluating reads that overlap the c.840 position of the SMN1 and SMN2 paralogs.

Differential inclusion of NEB exons 143 and 144 provides insight into NEB-related myopathy variant interpretation and disease manifestation.

Biallelic pathogenic variants in the gene encoding nebulin (NEB) are a known cause of congenital myopathy. We present two brothers with congenital myopathy and compound heterozygous variants (NC_000002.12:g.

Restrictive Strategy vs Usual Care for Cholecystectomy in Patients With Abdominal Pain and Gallstones: 5-Year Follow-Up of the SECURE Randomized Clinical Trial.

Importance: The 1-year results of the SECURE trial, a randomized trial comparing a restrictive strategy vs usual care for select patients with symptomatic cholelithiasis for cholecystectomy, resulted in a significantly lower operation rate after restrictive strategy. However, a restrictive strategy did not result in more pain-free patients at 1 year.

Objective: To gauge pain level and determine the proportion of pain-free patients, operation rate, and biliary and surgical complications at the 5-year follow-up.

CIAO1 loss of function causes a neuromuscular disorder with compromise of nucleocytoplasmic Fe-S enzymes.

Cytoplasmic and nuclear iron-sulfur (Fe-S) enzymes that are essential for genome maintenance and replication depend on the cytoplasmic Fe-S assembly (CIA) machinery for cluster acquisition. The core of the CIA machinery consists of a complex of CIAO1, MMS19 and FAM96B. The physiological consequences of loss of function in the components of the CIA pathway have thus far remained uncharacterized.

Phase 1 Open-Label Study of Omigapil in Patients With LAMA2- or COL6-Related Dystrophy.

Background And Objectives: Omigapil is a small molecule which inhibits the GAPDH-Siah1-mediated apoptosis pathway. Apoptosis is a pathomechanism underlying the congenital muscular dystrophy subtypes LAMA2-related dystrophy (LAMA2-RD) and COL6-related dystrophy (COL6-RD). Studies of omigapil in the (dy/dy) LAMA2-RD mouse model demonstrated improved survival, and studies in the (dy/dy) LAMA2-RD mouse model and the (Col6a1) COL6-RD mouse model demonstrated decreased apoptosis.

Effects of HMGCR deficiency on skeletal muscle development.

Pathogenic variants in were recently linked to a limb-girdle muscular dystrophy (LGMD) phenotype. The protein product HMG CoA reductase (HMGCR) catalyzes a key component of the cholesterol synthesis pathway. The two other muscle diseases associated with HMGCR, statin-associated myopathy (SAM) and autoimmune anti-HMGCR myopathy, are not inherited in a Mendelian pattern.

The expanding clinical and genetic spectrum of DYNC1H1-related disorders.

Intracellular trafficking involves an intricate machinery of motor complexes, including the dynein complex, to shuttle cargo for autophagolysosomal degradation. Deficiency in dynein axonemal chains, as well as cytoplasmic light and intermediate chains, have been linked with ciliary dyskinesia and skeletal dysplasia. The cytoplasmic dynein 1 heavy chain protein (DYNC1H1) serves as a core complex for retrograde trafficking in neuronal axons.

Differential inclusion of exons 143 and 144 provides insight into -related myopathy variant interpretation and disease manifestation.

Biallelic pathogenic variants in the gene encoding nebulin () are a known cause of congenital myopathy. We present two individuals with congenital myopathy and compound heterozygous variants (NM_001271208.2: c.

Pathogenic variants disrupt sarcomere contractility resulting in hypo- and hypercontractile muscle disease.

Troponin I (TnI) regulates thin filament activation and muscle contraction. Two isoforms, TnI-fast () and TnI-slow (), are predominantly expressed in fast- and slow-twitch myofibers, respectively. variants are a rare cause of arthrogryposis, whereas variants have not been conclusively established to cause skeletal myopathy.

Exome copy number variant detection, analysis, and classification in a large cohort of families with undiagnosed rare genetic disease.

Copy number variants (CNVs) are significant contributors to the pathogenicity of rare genetic diseases and, with new innovative methods, can now reliably be identified from exome sequencing. Challenges still remain in accurate classification of CNV pathogenicity. CNV calling using GATK-gCNV was performed on exomes from a cohort of 6,633 families (15,759 individuals) with heterogeneous phenotypes and variable prior genetic testing collected at the Broad Institute Center for Mendelian Genomics of the Genomics Research to Elucidate the Genetics of Rare Diseases consortium and analyzed using the seqr platform.

Digenic inheritance involving a muscle-specific protein kinase and the giant titin protein causes a skeletal muscle myopathy.

In digenic inheritance, pathogenic variants in two genes must be inherited together to cause disease. Only very few examples of digenic inheritance have been described in the neuromuscular disease field. Here we show that predicted deleterious variants in SRPK3, encoding the X-linked serine/argenine protein kinase 3, lead to a progressive early onset skeletal muscle myopathy only when in combination with heterozygous variants in the TTN gene.