CASQ1 mutations impair calsequestrin polymerization and cause tubular aggregate myopathy
Tubular aggregate myopathy (TAM) is a rare muscle disorder associated with progressive muscle weakness, cramps, myalgia, and exercise intolerance. Muscle biopsies from TAM patients typically show regular arrays of membranes tubules appearing as honeycomb-like structures. To date, two causative TAM gene are known: STIM1 and ORAI1. Both encode key factors in the regulation of Ca2+ homeostasis, and mutations in either gene result in excessive Ca2+ entry. Despite the discovery of two TAM genes, many TAM patients still await molecular diagnosis.