However, mapping of these sequences did not show linkage to any LG V markers until genetic analysis of a UV-inducible Xiphophorus melanoma model (described in the next sections) revealed significant linkage of the heavily melanized pigmentation phenotype and melanoma susceptibility to a CDKN2-related sequence that mapped to LG V (Nairn et al., 1996b). The gene discussed is CDKN2A; the disease is melanoma.