Nonobese diabetic/severe combined immunodeficiency (NOD/SCID, or genetic nomenclature NOD.Cg-Prkdcscid/J) mice,), and their derivatives NOD.Cg-PrkdcscidIl2rgtm1Sug/JicTac (NOG) and NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice are among the most-commonly used immunodeficient mouse strains today (21–23). The gene discussed is CTSG; the disease is severe combined immunodeficiency.