THE INHERITANCE AND DEVELOPMENT OF CUP AND DISC DIAMETERS

Abstract

The familial resemblances in disc diameter (d) and cup diameter residual (e) were studied in 845 individuals forming 297 families and 1040 pairs of spouses and 1st-degree relatives. The cup diameter residual was computed as the difference between the observed cup diameter and the cup diameter expected from the disc diameter and the age, according to a multiple regression equation. The results for d and e were similar. Spouses did not resemble each other at all. The resemblance between 1st-degree relatives was quite substantial. There were no major influences of sex-linkage, dominance or common environment, and no obvious maternal effects. The familial resemblance was essentially additively genetic in origin. The heritability was estimated at 2/3. The remaining variance was attributed to errors of development. Other surface dimensions of the optic nerve head are related.