Both Orai1 and STIM1 are critical for T cell immunity as evident from loss of function mutations of Orai1 or STIM1 which eliminate SOCE and result in impaired cytokine production, abrogated T cell activation, and severe combined immunodeficiency in patients (Feske et al., 2006; Gwack et al., 2008; Oh-Hora et al., 2008; Picard et al., 2009). This evidence concerns the gene ORAI1 and severe combined immunodeficiency.