DNA cross-link repair 1C (Dclre1c) encodes a member of the SNM1 family of nucleases and is involved in V(D)J recombination and DNA repair. This protein has single-strand-specific 5'-3' exonuclease activity; it also exhibits endonuclease activity on 5' and 3' overhangs and hairpins. The protein also functions in the regulation of the cell cycle in response to DNA damage. Homozygous knockout mice for this gene exhibit severe combined immunodeficiency with sensitivity to ionizing radiation. Mutations in this gene in humans can cause Athabascan-type severe combined immunodeficiency (SCIDA) and Omenn syndrome. Alternative splicing results in multiple transcript variants encoding different isoforms.