Chromosome heteromorphism analysis in cases of disputed paternity.

Blood test results, using standard procedures, failed to exclude the alleged father as the biological father of a child in a case of disputed paternity. Using 21 different systems, the probability of exclusion for the man was 98.19%, and the probability of paternity was only 93.90% with a paternity index of 15.48. Chromosome heteromorphisms of all three individuals were studied. By comparison of fluorescent markers of chromosomes 13, 14, 15, 21, and 22, the child was shown to inherit one homologue of each of these chromosomes from the mother, but none were like the heteromorphisms of the alleged father. This excluded him as the biological father.