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Highlights The inaugural Clinical and Scientific Conference on Adenylosuccinate Synthetase 1 (ADSS1) myopathy was held on June 3, 2024, at the National Institutes of Health (NIH) National Center for Advancing Translational Sciences (NCATS) in Rockville, Maryland, USA. ADSS1 myopathy is an ultra-rare, inherited neuromuscular disease. Features of geographical patient clusters in South Korea, Japan, India and the United States of America were characterised and discussed. Pre-clinical animal and cell-based models were discussed, providing unique insight into disease pathogenesis. The biochemical pathogenesis was discussed, and potential therapeutic targets identified. Potential clinical and pre-clinical biomarkers were discussed. An ADSS1 myopathy consortium was established and a roadmap for therapeutic development created.

Hyperammonemia is a rare cause of adult episodic encephalopathy. Citrin deficiency resulting in citrullinemia type 2 (CTLN2) can lead to recurrent delirium in adults. Here we report a case of adult onset episodic encephalopathy due to citrin deficiency. A 40 years old male presented with one-year history of episodic encephalopathy triggered by high protein and fat diet. He also had chronic pancreatitis and subacute intestinal obstruction which is a novel manifestation of CTLN2. Evaluation showed elevated blood liver enzymes, ammonia, and citrulline. MRI brain showed frontal hyperintensities and bulky basal ganglia which have not been reported. Diagnosis was confirmed by next-generation sequencing which showed a novel variant c. 1591G > A in exon15 of SLC25A13. Hyperammonemic syndromes should be considered in differential diagnosis of episodic encephalopathy in adults. This report shows novel features of subacute intestinal obstruction and MRI findings in CTLN2 expanding spectrum of manifestation.

VMA21-related myopathy is one of the rare forms of slowly progressive myopathy observed in males. Till now, there have been only a handful of reports, mainly from Europe and America, and two reports from India. Here, we describe a case of genetically confirmed VMA21-associated myopathy with clinical, histopathological, and imaging features with a list of known VMA21 mutations. A 29-year-old man had the onset of symptoms at 18 years of age with features of proximal lower limb weakness. Muscle magnetic resonance imaging showed the preferential involvement of vasti and adductor magnus. A biopsy of the left quadriceps femoris showed features of autophagic vacuolar myopathy with vacuoles containing granular eosinophilic materials. In targeted next-generation sequencing, hemizygous mutation in the 3’ splice site of intron 2 of the VMA21 gene (c.164–7 T > A) was identified and confirmed the diagnosis of X-linked myopathy with excessive autophagy. This report expands the phenotypic and genotypic profile of VMA21-related myopathy, with a yet unreported mutation in India.

Glutaric aciduria type-1 (GA-1) is a rare metabolic disorder due to mutation in GCDH gene resulting in varied clinical manifestations. Here we report a case of late-onset GA-1 with acute myelo-neuropathy and chronic renal failure. Institutional ethics committee approval was obtained and genetic analysis was done by clinical exome sequencing. Here we present 19 year-old-adolescent male with chronic renal disease for 2 years presented with 5 months history of sudden onset weakness of proximal and distal lower limbs and bladder retention. This was preceded by recurrent episodes of vomiting. On clinical examination he had features of myeloneuropathy. Laboratory evaluation showed significant elevation of blood glutaryl carnitine with very low free carnitine, while extensive white matter signal changes with diffusion restriction, subependymal nodules and involvement of internal capsule were evidenced on brain magnetic resonance imaging. Diagnosis was confirmed by clinical exome sequencing which showed a pathogenic homozygous missense mutation in exon 11 of GCDH gene (c .120 C>T, p.His403Tyr). This report expands phenotypic spectrum of GA-1 to include late onset acute myelo-neuropathy with chronic renal failure. A high index of suspicion is required since early treatment might decelerate further disease progression.

Introduction ORAI-1 is a plasma membrane calcium release-activated calcium channel that plays a crucial role in the excitation–contraction of skeletal muscles. Loss-of-function mutations of ORAI-1 cause severe combined immunodeficiency, nonprogressive muscle hypotonia, and anhidrotic ectodermal dysplasia. Autosomal dominant gain-of-function mutation causes Stormorken's syndrome, which includes tubular aggregate myopathy along with bleeding diathesis. Methods This is a description of a genetically confirmed case of ORAI-1-associated myopathy with clinical, histopathological, and imaging characteristics and a detailed literature review. Results We report an 18-year-old woman who presented with 2-and-a-half year history of slowly progressive proximal lower limb weakness and ophthalmoparesis. Her serum creatine kinase levels were normal. Magnetic resonance imaging of the muscle showed predominant fatty infiltration of the glutei and quadriceps femoris. Histopathological analysis of muscle biopsy was suggestive of congenital fiber-type disproportion (CFTD). Clinical exome sequencing showed novel homozygous nonsense pathogenic variant NC_000012.12 (NM_032790.3): c.205G > T (p.Glu69Ter) in ORAI-1 gene. Conclusion This report expands the phenotypic spectrum of ORAI-1-related myopathy to include congenital myopathy—CFTD with ophthalmoparesis, a novel manifestation.

Neuromuscular features are common in mitochondrial DNA (mtDNA) disorders. The genetic architecture of mtDNA disorders in diverse populations is poorly understood. We analysed mtDNA variants from whole‐exome sequencing data in neuromuscular patients from South Africa, Brazil, India, Turkey and Zambia. In 998 individuals, there were two definite diagnoses, two possible diagnoses and eight secondary findings. Surprisingly, common pathogenic mtDNA variants found in people of European ancestry were very rare. Whole‐exome or ‐genome sequencing from undiagnosed patients with neuromuscular symptoms should be re‐analysed for mtDNA variants, but the landscape of pathogenic mtDNA variants differs around the world.