A homozygous mutation in the murine Dna‐pkcs leading to a C‐terminal truncation of the protein results in severe combined immunodeficiency, SCID 17, and a kinase‐dead DNA‐PKcs‐mutated protein leads to Ku70/Ku80‐ and p53‐dependent embryonic lethality in mice 18. The gene discussed is PRKDC; the disease is severe combined immunodeficiency.