The Effects of Isolates on the Frequency of a Rare Human Gene

Abstract

Considerations concerning inbreeding "isolates" in human populations are applied to the data on the recessive trait, juvenile amaurotic idiocy, in Sweden. Only by postulating a frequency of cousin marriages in the isolates exceeding the rate for the general population can the observed frequency of the trait be explained. Likewise, under the assumption that all cases occur in isolates, the size of the isolates is estimated to be approx. 200 and the proportion of the population contained in them is estimated to be 40%.