Paternity testing with an absent mother. The probability of exclusion of red cell surface antigen, Gm, Hp, and HLA systems in North American whites and blacks.

Blood tests in cases of disputed paternity can be extremely useful even when the mother's blood sample is not available. The mean probability of exclusion (A) of red cell surface antigen, Gm, Hp, and HLA systems was determined in this situation for North American whites and blacks by creating pairs of a man and an unrelated child. In whites, the most valuable of the systems investigated to indicate nonpaternity for false fathers were HLA, Rh, Fy, and MNSs, in that order. HLA, MNSs, and Gm were the most valuable systems in blacks. With all of the genetic systems used in this study, the combined probability of exclusion (CPE) of men falsely accused of paternity, in cases where the mother is absent, is approximately 95 percent for whites and 92 percent for blacks. Since only indirect exclusions are possible without the mother, the common test panel of HLA and red cell antigens may not always allow an adequate study. Extended testing is recommended to include additional genetic systems in order to achieve an average combined probability of exclusion of at least 95 percent.