BLM heterozygous mutant mice developed T cell lymphoma at a much more rapid rate when challenged with murine leukemia virus (Goss et al., 2002) and the frequency of intestinal tumor development is higher when crossed with Adenomatous Polyposis Coli (APC) gene heterozygous mutant mice. The gene discussed is BLM; the disease is T-cell non-Hodgkin lymphoma.