ANTIBODY TO HEREDITARY HUMAN GAMMA-GLOBULIN (GM) FACTOR RESULTING FROM MATERNAL-FETAL INCOMPATIBILITY.

Multiple samples of serum from a Gm(a-) female mated to a Gm(a+) male were obtained before, during, and after each of four normal uncomplicated pregnancies and tested for antibody to human gamma globulins of differing genetic types. An agglutinator for the Gm(a) factor first appeared in the mother's serum during the third trimester of the fourth pregnancy. The newborn (male) was genotypically Gm(a+), since his serum contained, in addition to maternal Gm(a-) gamma globulin, small amounts of Gm(a+) gamma globulin.