Genes in mice that affect susceptibility to cortisone-induced cleft palate are closely linked to Ir genes on chromosomes 2 and 17.

Inbred and congeneic strains of mice have been examined for susceptibility to cortisone-induced cleft palate, and the role of genes linked to H-2 on chromosome 17 has been confirmed. Increasing degrees of susceptibility were associated with the H-2d, H-2b, H-2k, and H-2a haplotypes, respectively, with H-2q and H-2s also being associated with fairly high levels of susceptibility. Evidence was obtained that suggests that one gene maps within the B region of H-2, and that a second H-2 linked gene which acts by complementation maps to the right of E. Another gene affecting this trait is closely linked to the H-3 and Ir-2 loci on the second chromosome.