RAG MUTATIONS IN HUMAN B-CELL-NEGATIVE SCID

Patients with human severe combined immunodeficiency (SCID) can be div ided into those with B lymphocytes (B+ SCID) and those without (B- SCI D). Although several genetic causes are known for B+ SCID, the etiolog y of B- SCID has not been defined. Six of 14 B- SCID patients tested w ere found to carry a mutation of the recombinase activating gene 1 (RA G-1), RAG-2, or both. This mutation resulted in a functional inability to form antigen receptors through genetic recombination and links a d efect in one of the site-specific recombination systems to a human dis ease.