Genetic and immunological factors in human recurrent abortion.

The theoretical causes of recurrent spontaneous abortion may be several. Gill and others have suggested that the human disease may be mimicked by the rodent genetic diseases, as exemplified by the T locus in mice. He would suggest that there may be lethal recessive gene phenomena which may cause repeated abortion, or if the abortion is prevented by immunological means the birth of genetically defective individuals. The evidence presented here shows that prevention of abortion by immunological treatment, that is immunisation of the wife with paternal lymphocytes, is associated with a very high success rate, and the children born do not have more than the normal incidence of birth defects. Thus far, over the 7 years of study, the children also appear to develop normally. Probably the reason for this is that the methods of selection for treatment tend to exclude quite effectively those couples with pure genetic problems. In particular, the the exclusion of women who have had more than one live child removes a group of women who might have lethal recessive problems which would only affect 25-50% of the offspring. The interactive gene products that may produce abortion of all pregnancies, suggested as a theoretical concept by Gill, would be expected to show an incidence no more than the square root of the frequency of the recessive disease, and are probably too few to be seen even in the more than 1,500 couples we have studied.