THE GENETICS OF CORNEA PLANA CONGENITA

Cornea plana congenita is believed to occur in a mild autosomal domina nt (CNA1) and a more severe autosomal recessive (CNA2) form. We recent ly assigned a CNA2 locus to a region on chromosome 12 by linkage analy sis. In this study we compared these traits clinically and genetically . Using the horizontal corneal refraction value in diopters (D) as a p arameter, a control population (n=473) had a mean value of 43.4 (SD 1. 5 D) for men and 43.7 (SD 1.6 D) for women, whereas in 51 subjects aff ected with CNA2 the mean value was 29.9 (SD 5.2 D) and in five subject s affected with CNA1 the mean value was 37.8 (SD 1.6 D). By Linkage an alysis in two CNA1 families the CNA2 locus could be conclusively exclu ded. These data suggest that at least two forms of hereditary cornea p lana exist which are both clinically and genetically distinct.