OBSERVATION OF NULL ALLELES APPARENTLY DUE TO DELETIONS

After examining 2 paternity cases in 17 classical, 4 RFLP and 5 PCR-VN TR systems, isolated pseudo-exclusions were observed in the polymorphi sm D2S44 (YNH24). In both cases the ''exclusions'' were due to apparen t opposite homozygosity. The application of different restriction enzy mes, PCR amplification and varying electrophoretic conditions each led to an equivalent result of a 1-band-pattern with a mismatch between b oth father/child pairs. From these results the authors conclude that a complete or almost complete loss of the alleles is the most probable explanation.