Of the enrolled patients, 26 (2 females) had the SD phenotype, including the Btk gene in six, IL2RG in four, WASP in three, CD40L in three, gp91 in three, gp47 in one, RAG2 in one, and four with CVID and one with SCID without identified genetic defects. The gene discussed is BTK; the disease is severe combined immunodeficiency.