J:73835

Linkage analysis was performed on a population of (A/J x SKC)F1 x SKC backcross animals to map the locus responsible for heriditary keratoconus. Inbred strain SKC is a spontaneous mutant exhibiting a phenotype similar to the hereditary human corneal disease keratoconus. Adult male SKC animals develop keratoconus while adult male A/J animals do not. Interestingly, castrated SKC males exhibit a diminished phenotype and SKC females injected with testosterone develop keratoconus, indicating androgen-dependence of the phenotype. Krcn1, a locus at 18.7 cM on mouse Chromosome 17 was identified in linkage to keratoconus with a maximum LOD=9.77 at D17Mit32 and D17Mit34. Homozygosity for SKC-derived alleles at Krcn1 confers increased incidence of keratoconus. Krcn1 is linked to the H2 locus, and genes mapping near Krcn1 include C4, Tnxb, Cyp21a1, C4a, and Rds. Cyp21a1 and C4a are considered possible candidate genes for Krcn1.