Abstract
A genetic analysis has been made of published and new data on the familial occurrence of severe pre-eclampsia in primigravid women. This has shown that the condition may be largely a Mendelian recessive one. Bcause the condition occurs only in pregnancy, and because susceptible women cannot otherwise be identified, it is difficult to decide whether the genotype of the parent or of the offspring carried in utero leads to the condition. Data on the incidence of severe pre-eclampsia in the relatives of women who have suffered eclampsia support the maternal genotype hypothesis, while similar data, in which the index cases were women who had had severe pre-eclampsia, are more compatible with the fetal genotype hypothesis. Data on the incidence of the condition in blood relatives of index cases compared to the incidence in their corresponding in-laws are now required. Such a comparison would allow a choice to be made between the two hypotheses if one or the other were correct, or would assess the contribution of each if a genotype X genotype interaction were involved. Recurrent severe pre-eclampsia seems to have the same genetic basis as the more common primigravid type. However, mild, that is non-proteinuric, pre-eclampsia usually seems to be inherited independently of the severe form.