The Diagnostic Journey from Rhabdomyolysis to Myopathy with Tubular Aggregates: A Family-Based Case Report and Review of the Literature

Introduction/Aims: Myopathies with Tubular Aggregates (TAM) are rare, chronic neuromuscular disorders that may be inherited or acquired. The aim of this report is to present the diagnostic pathway and the challenges encountered in a family with three members affected by TAM caused by a rare ORAI1 variant. Case report: Two siblings (15 and 11 years old) developed severe rhabdomyolysis triggered by a viral respiratory infection. Histopathological analysis demonstrated numerous tubular aggregates with mild focal secondary inflammatory changes and no immunophenotypic evidence of autoimmune inflammatory myopathy. Whole-exome sequencing identified a likely pathogenic heterozygous missense variant, NM_032790.3(ORAI1):c.319G>A (p.Val107Met), in the ORAI1 gene, in both children and their asymptomatic mother. Conclusions: The identification of a rare ORAI1 variant in this family supports the association with TAM, broadens the spectrum of phenotypic presentation, and illustrates the phenotypic variability that may exist even among affected members of the same family. Careful interpretation of inflammatory changes in muscle biopsy, together with immunohistochemical and genetic findings, is essential to avoid misclassification of hereditary tubular aggregate myopathy as autoimmune inflammatory myopathy.