Paternal exclusion: allele sharing in microsatellite testing.

BACKGROUND: A paternity disagreement analyzed with 15 autosomal microsatellite markers indicated allele sharing between the mother, questioned child and the alleged father generating an inconclusive paternity result. DESIGN AND METHODS: In total, 15 autosomal and 17 Y tandem repeat loci were analyzed using AmpF/STR Identifiler, AmpF/STR Y-filer kits followed by six microsatellite markers on X chromosome in DNA extracted from peripheral blood samples of the mother, questioned child and alleged father. RESULTS: Microsatellite analysis examined with 15 autosomal short tandem repeats (STRs) indicated at least one allele sharing at 14 loci between the mother, questioned child and alleged father except for the TPOX locus where a paternal-child allele mismatch was observed. Y chromosome investigations using 17 repeat markers signified the case as non-paternity (exclusion). A complete match of the six X chromosome loci in the questioned child with the mother was observed. CONCLUSIONS: Our investigations on inconclusive paternity due to atypical allele sharing in autosomal microsatellites were resolved with X- and Y-chromosome STR analyses confirming the case as non-paternity.