<p>ADSS1 myopathy is an ultra-rare autosomal recessive neuromuscular disorder caused by biallelic pathogenic variants in <i>ADSS1</i> encoding the striated muscle isozyme of adenylosuccinate synthase involved in purine metabolism. Despite advances in clinical, genetic and mechanistic understanding, the condition remains inconsistently represented across clinical, genomic and registry systems. It is variably labelled as ADSSL1-related distal myopathy, nemaline myopathy, or more recently, a metabolic myopathy reflecting an inborn error of metabolism. These inconsistencies have practical consequences. Gene nomenclature and annotation drift introduces avoidable errors in variant interpretation, panel design and data integration, while imprecise disease classification based on early observations reduces clinical ascertainment of new cases, degrades longitudinal natural history studies, and delays clinical trial readiness. At the level of international coding systems, ADSS1 myopathy is misclassified under legacy terminology in SNOMED CT and Orphanet and is not independently represented in ICD-11. This position statement argues for harmonization of both gene and variant nomenclature and disease classification. We promote adoption of <i>ADSS1</i> (HGNC:20093) as the canonical gene symbol, adenylosuccinate synthase 1 (ADSS1) as the canonical protein name, with ADSSL1 retained as a historical synonym, and PURA1 recognized as a protein alias. We further propose classification of ADSS1 myopathy as a metabolic myopathy caused by an inborn error of purine metabolism (more concisely, a metabolic myopathy), with distal and nemaline descriptors retained as histopathological modifiers. Standardization is a low-cost, high-impact intervention that will improve diagnostic accuracy, enable integration of multi-omics datasets, strengthen registries and accelerate therapeutic development for this globally dispersed ultra-rare disease.</p><p><b>Clinical trial number:</b> Not applicable.</p>