Interaction between adenosine deaminase and ABO system polymorphisms: effects on intrauterine survival and reproduction.

Adenosine deaminase (ADA) phenotype and ABO blood groups have been determined in 572 consecutive newborn infants, in 770 schoolchildren, in 139 women delivering a liveborn infant, and in 87 women with habitual abortion. ABO-incompatible newborn infants showed a higher proportion of ADA2 carriers as compared to compatible newborns. The incidence of clinically relevant neonatal jaundice among incompatible infants carrying ADA2 was lower as compared to compatible infants carrying this gene. In newborn infants, schoolchildren, and women with habitual abortion the proportion of A, B, and AB among ADA2 carriers was higher as compared to ADA1/ADA1 individuals. In fertile women, on the contrary, the proportion of A, B, and AB among ADA2 carriers was lower as compared to ADA1/ADA1 women. This suggests that non-O ADA2 carrier genotypes may lose in the reproductive stage the selective advantage accumulated during the early stages of development.