Analysis on the allele mutations of STR loci in paternity testing

Objective To analyze the characteristic of allele mutations of 15 short tandem repeats in paternity testing.Methods 676 paternity testing cases were detected by using IdentifilerTM system.When one or two-locus exclusions had been observed,further examination was performed by using HLA system or Y-STRs typing.Results 1304 meiosis were investigated among the 676 cases of confirmed paternity,19 mutations were identified at D18S51(n=4),D2S1338(n=3),D8S1179(n=2),D16S539(n=2),vWA(n=2),D7S820(n=2),D13S317(n=2),D5S818(n=1) and TH01(n=1) loci.No mutation was observed at D21S11,FGA,D3S1358,D19S433,TPOX and CSF1P0 loci.In all of these 19 mutations,a single-step mutation Loas observed in 17 cases.A double-step mutation and a four-step mutation were observed in 1 case respectively.In addition,a single-locus mutation was observed in 18 cases,and a double-locus mutation was observed in 1 case.The ratio of paternal versus maternal mutations was 13:2,and four indistinguishable mutations were observed.Conclusion In paternity testing,when one or two STR mutations were observed using the IdentifilerTM system,other more genetic markers should be added to avoid the false conclusion.