Genetic study on the congenital dislocation of the hip.

A clinical and epidemiological study on congenital dislocation of the hip (CDH) was attempted with a genetic analysis of this condition, and the following results were obtained. The frequency of CDH in the general population is 0.08% in males and 0.59% in females, the latter being clearly higher. In examining the changes in the frequency of CDH over the years using the data reported in the literature, a statistically significant tendency for the frequency to decrease in more recent years was noted. It was confirmed by the recurrence rate of the subsequent sibling and twin data that CDH is a multifactorial disease, and, in estimating its heritability, in males h2 = 0.94-1.01 and in females h2 = 1.38, which are markedly high estimates exceeding the limit of 1. This is perhaps attributable to the small number of patients in this series and to the differences in the characteristics between the data on the frequency of CDH in the general population and those of the present pedigree study. When the corrected value of the frequency in the general population was used in estimating the heritability, in males h2 = 0.54 approximately 0.74 and in females h2 = 0.68, which are almost identical to the American data.