Chromosomal localization of mouse hair keratin genes

Many genetic defects are known to cause abnormal development of the coat in mice. Hair keratin genes would seem to be particularly promising candidates among the potential targets of these mutations in mice and of inherited hair-related abnormalities in humans as well. We used specific probes from cloned and sequenced mouse hair keratin cDNAs (MHKA-2, MHKB-1, and MHKB-2) to assess linkage of hair keratin genes and mouse mutations. We analyzed DNA from the progeny of interspecies backcrossed mice for segregation of hair mutations, hair ("hard") keratin alleles, and epidermal ("soft") keratin alleles (Krt-1 and Krt-2 loci). The results suggest that most, if not all, hair keratin genes (types Ia and IIa) are part of the Krt-1 locus on chromosome 11 and Krt-2 locus on chromosome 15, respectively. Linkage of the hair keratin genes and the mutations Re, Den, and Bsk on chromosome 11, and Ca, Sha, and Ve on chromosome 15 suggests that these mutations may possibly involve altered hair keratin expression or structure. In addition, the nondispersion of homologous keratin genes in the mammalian genome suggests that a domain organization of the genes has influenced evolution of the keratin gene family and that the organization may play a significant role in tissue-specific and developmental regulation of keratin gene expression as well.