[Application of 17 Y-chromosome specific STR loci in paternity testing].

The purpose of this study was to expore the ability of discrimination of the AmpFlSTR YfilerTM PCR amplification kit containing 17 Y-STR loci and the allelic mutation in the practice of paternity testing in Chinese population. 36 non-paternity father/son pairs and 84 confirmed father/son pairs, which had been previously genotyped by using Reliagene Y-PLEXTM 6 commercial kit and the "9 Y-STR multiplex with reduced-size amplicons" developed by our laboratory, were subjected to Y-STR genotyping at 17 loci using the AmpFlSTR YfilerTM PCR amplification kit. 17 Y-STR loci were amplified in single multiplex and the PCR products were detected by using ABI PrismTM 3100 DNA Sequencer. The number of Y-STR exclusion for each non-paternity father/son pair and the mutation events for each confirmed father/son pair were calculated and the observed results were compared with our previous reported data determined by Reliagene Y-PLEXTM 6 kit and the "9 Y-STR multiplex with reduced-size amplicons" . The results showed that out of 36 non-paternity father/son pairs subjected to Y-STR genotyping by using the AmpFlSTR YfilerTM kit, one case with no Y-STR exclusion of paternity and 35 cases with more than 3 Y-STR exclusions for each father/son pair were observed. The percentage of cases with more than 3 Y-STR exclusions in all the tested non-paternity cases for YfilerTM kit was 97.22% (35/36), which was more than that of Reliagene Y-PLEXTM 6 kit (92.11%, 35/38) and our "9 Y-STR multiplex with reduced-size amplicons" (91.67%, 33/36). Except for single father/son pair with no Y-STR exclusion, an average of 11.3 Y-STR exclusions was observed in other 35 non-paternity father/son pairs. In the 84 confirmed father/son pairs, 5 mutation events with a single unit repeat change at DYS437, DYS439, DYS635, DYS389Ⅱ and DYS19, respectively, were identified using the YfilerTM kit. The average mutation rate was estimated at 3.50×10-3 per locus per generation. The cases with Y-STR mutation events in all tested confirmed father/son pairs for YfilerTM system were 5.95% (5/84), which was significantly higher than that of Y-PLEXTM 6 (2.15%, 2/93) and "9 Y-STR multiplex with reduced-size amplicons" (no mutation events in the same 84 confirmed father/son pairs). It is concluded that the YfilerTM kit which allowing simultaneous analysis of 17 Y-STR loci offers a high ability of discrimination for paternity testing, however, the Y-STR allelic mutation of the YfilerTM system can not be neglected.