The severity of the clinical phenotype correlates with residual RAG1/2 catalytic activity and may range from severe combined immunodeficiency (SCID) in null RAG 1/2 variants with absent T or B lymphocyte to a less severe phenotype with milder infections, autoimmunity, and granulomas (CID-G/AI) typically with a later onset in life (27). The gene discussed is RAG1; the disease is severe combined immunodeficiency.