ORAI1 and transient myeloproliferative syndrome: <b>Background:</b> Tubular aggregate myopathy (TAM) is an autosomal dominant myopathy that results from gain-of-function mutations in the <i>STIM1</i> and <i>ORAI1</i> genes, which encode the two key proteins that coordinate store-operated Ca<sup>2+</sup> entry in skeletal muscle and other cell types.