Multi-allelic Patterns Observed at Y-STR Loci: A Case Report

The forensic relevance of Y-STR analysis is well understood and widely documented. In this report, the authors have described twounusual multi-allelic patterns in Y-STR profiles of individualsobserved during forensic examination.The first is a case of a bi-allelic pattern at the locus DYS391observed in a father/son duo in a paternity dispute. The second case is of a tri-allelic pattern at the locus DYF387S1a/b observed in the Y-STR profile of a suspected perpetrator in a case of sexual assault.In both cases, the individuals belong to theHimalayan stateof Sikkim in Northeast India, and this is the first report of such abnormal Y-STR patterns observed in this population. Probable causes for these multi-allelic patterns and the relevance of these findingsfor forensic DNA analysis have been discussed