Fourth, genetic mutations of non-X linked agammaglobulinemia encoding for pre-BCR and/or BCR complex (such as IGHM, CD79a, CD79b, and IGLL1 genes) and for activating mTOR signaling (such as PI3KD and PIK3R1 genes). The gene discussed is BCR; the disease is Bruton-type agammaglobulinemia.