STIM1Mutation Associated with a Syndrome of Immunodeficiency and Autoimmunity

Abstract
A mutation in ORAI1, the gene encoding the pore-forming subunit of the Ca2+-release–activated Ca2+ (CRAC) channel, abrogates the store-operated entry of Ca2+ into cells and impairs lymphocyte activation. Stromal interaction molecule 1 (STIM1) in the endoplasmic reticulum activates ORAI1–CRAC channels. We report on three siblings from one kindred with a clinical syndrome of immunodeficiency, hepatosplenomegaly, autoimmune hemolytic anemia, thrombocytopenia, muscular hypotonia, and defective enamel dentition. Two of these patients have a homozygous nonsense mutation in STIM1 that abrogates expression of STIM1 and Ca2+ influx.