The murine dominant gene Cat-2 was located on chromosome 1 between the loci of fuzzy and leaden. Subsequent linkage analysis revealed one recombinant between Cat-2t and isocitrate dehydrogenase-1, and one between Cat-2t and gamma E-crystallin among 338 offspring in three-point backcrosses. The resulting genetic distance between the loci is 0.3 +/- 0.3 cM. The very close linkage between the Cat-2 and the gamma-crystallin gene cluster together with the finding of reduced gamma-crystallin transcripts in mutant lenses suggest strongly that the gamma-crystallin genes may be candidate genes for the Cat-2 mutations.