[Two unusual cases of half-sibling test with DNA polymorphism].

In usual paternity cases, the putative man and the mother-child couple are alive. However, there are some cases in which putative man and mother were deceased and only children were available for analyses. It is difficult to determine the presence or absence of half-sibling relationship from analyses of conventional blood group markers (CBGM). In this study, five kinds of single locus DNA probes were applied to 2 half-sibling cases. To decide usefulness of single locus DNA probes, we defined likelihood ratio of half-sibling (LRHS) based on the likelihood ratio of paternity (LRP) and also investigated the distribution curves of log10 LRHS in cases of unrelated combinations and half-sibling combinations. Distribution curves of log10 LRHS from DNA analyses in the cases of unrelated combinations and half-sibling combinations is more clearly separated than from CBGM. Single locus DNA probes are considered to be more informative for half-sibling cases.