Stuart Clotting Defect. II. Genetic Aspects of a `New' Hemorrhagic State

Abstract

The Stuart defect, a newly recognized hemorrhagic disease, was found segregating in a large family in the mountains of North Carolina. Information was obtained on 164 persons in five generations; laboratory studies were performed on 14 members of generations III, IV, and V. The genetic data obtained are consistent with the hypothesis that the Stuart defect is transmitted as a highly penetrant but incompletely recessive autosomal characteristic. It would appear that the mutant gene is present in the population at a frequency not greater than .001, and the heterozygotes are not more frequent than .002. Heterozygotes were found to have Stuart factor levels ranging from 21 to 52% of normal controls. It is emphasized that heterozygotes, especially females, may have mild symptoms under appropriate stress.