ORAI1 and combined immunodeficiency: For instance, mutations disrupting Mg2+ (MAGT1) or Ca2+ (STIM1, ORAI1) transport in lymphoid cells (Vaeth and Feske, 2018) cause combined immunodeficiencies (CID) predominantly due to defects in functions of T cells and NK cells, rather than B cells (Vaeth and Feske, 2018).