Development Of Multiplex Assay And Analysis Of Haplotype Diversity And Mutation Rates For 13 RM Y-STRs In Chinese Han Population Of Hubei Province

Background Y chromosomal STR typing has been widely used in forensic case work especially in sexual assault cases, paternity testing of male offspring and group source inference of biological samples. However, in some isolated and inbred populations, the differentiation power of conventional Y-STRs is limited because of Y-STRs’ paternal inheritance characteristics. Furthermore, currently used Y-STRs lack the ability to differentiate male individuals from the same paternal lineage, unless a mutation occurred, they have the same haplotype. Later on, the proposal of rapidly mutating Y-STRs(RM Y-STRs) made it possible to improve the discrimination capacity of Y-STRs as well as differentiating male relatives from the same paternal lineage.Objective To investigate the allelic distribution and haplotype diversity of 13 RM Y-STRs in Chinese Han population of Hubei province; to construct a multiplex assay consist of the 13 Y-STRs and investigate their mutation rates in Chinese Han population in order to assess their application value in Chinese population.Methods 1. Collect 252 unrelated male blood samples and test their genotype of 13 RM Y-STRs, confirm the repeat structure and nomenclature of each locus by fragment sequencing and analyze the gene diversity and haplotype frequency; 2. Redesign the primers of each locus according to their fragment length and primer designation principles for multiplex assay, construct a multiplex amplification assay consist of the 13 RM Y-STRs; 3. Collect father-son pair samples for the mutation investigation using the former multiplex assay and assess the application value of rapidly mutating Y-STRs in Chinese population.Results 1. Repeat structure and nomenclature of 13 RM Y-STRs is confirmed by this study. All 13 loci showed great polymorphism in Chinese population, gene/haplotype diversity index ranges from 0.7862 to 0.9953. 2. The multiplex assay for 13 RM Y-STR markers showed satisfying amplification result with stable genotype and good repeatability. 3. 19.0% father-son pairs were differentiated by the 13 RM Y-STRs. 9 of the 13 markers have mutation rates above 10-2 which correspond to the former reports. Mutation rates of loci DYF403S1 b, DYS526 b, DYS570 and DYS626 are relatively low which range from 5×10-3 to 7×10-3.Conclusion All of the 13 RM Y-STR markers showed excellent gene/haplotype diversity in Chinese Han population of Hubei province, and 9 of them had the mutation rates above 10-2 which indicates great potential of the application of rapidly mutating Y-STR markers in Chinese population. Though enriching the frequency and mutation data of other groups and readjusting Y-STR loci combination according to Chinese specificity, the advantages of rapidly mutating Y-STRs would be fully taken of. The multiplex assay developed in this study with accurate genotype, strong stability and high sensitivity will provide an effective reference for the application of RM Y-STRs in forensic practice.