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目的研究Y-STR的异常基因分型结果,获得更多的Y-STR遗传信息,为法医学鉴定提供依据。方法根据常染色体STR基因座的分型结果,将标本分为2组:“排除父子关系”的为1组,共49个案例,98个标本;“支持父子关系”的为1组,共252个案例,509个标本。采用Chelex方法提取血样DNA,使用Amp Fl STRYfilerTM试剂盒扩增16个Y-STR基因座并通过ABI 3130xl测序仪电泳、分析Y-STR基因型。结果在“支持父子关系”的509个标本中,除了单个基因的一步突变以外,9个标本出现了异常基因型。有3对父子(6个标本)的异常基因型出现在DYS385基因座,表现为三带型(13,14,18,峰高比例约为1∶1∶2)、四带型(13,17,18,20,峰高比例约为2∶1∶1∶1)、四带型(13,18,19,21,峰高比例约为2∶1∶1∶1);有1对父子在DYS439基因座出现双基因(12,13,其峰高比例约为1∶1);另外1对父子,儿子在DYS389II基因座为双基因(28,29,其峰高比例约为1∶1),但其父为正常单基因(28)。在“排除父子关系”的98个标本中有两个标本均在DYS448基因座发生了基因缺失。经统计,单基因座出现多个基因的发生率为1.4%,基因缺失的发生率为0.57%。结论 Y-STR分型中异常基因型的发生率虽然不高,但仍然存在一定的比例,在法医工作中需慎重对待,增加更多的STR基因座有助于正确地判断分析。
Objective To study the abnormal genotyping results of Y-STR and to obtain more Y-STR genetic information, so as to provide basis for forensic identification. Methods According to the autosomal STR loci typing results, the specimens were divided into two groups: “exclude father-son relationship,” a group of 49 cases, 98 specimens; Group, a total of 252 cases, 509 specimens. Blood samples were extracted using the Chelex method and 16 Y-STR loci were amplified using the Amp Fl STR® Yfiler ™ kit and analyzed by ABI 3130xl sequencer electrophoresis to analyze the Y-STR genotype. Results In 509 samples of “supportive parent-child relationship”, except for one-step mutation of a single gene, nine samples showed abnormal genotypes. The abnormal genotypes of 3 pairs of father and son (6 specimens) appeared in the DYS385 locus, which showed three bands (13,14,18, peak height ratio of about 1: 1: 2) , 18,20, the peak height ratio of about 2: 1: 1: 1), four band type (13,18,19,21, peak height ratio of about 2: 1: 1: 1) DYS439 locus showed a double gene (12,13, the peak height ratio of about 1: 1); another pair of father and son, the son of the DYS389II locus as a double gene (28,29, the peak height ratio of about 1: 1) , But its father is a normal single gene (28). Two of the 98 specimens of “excluding father-child relationship” were genetically deleted at the DYS448 locus. According to statistics, the incidence of multiple genes in single locus was 1.4%, and the incidence of gene deletion was 0.57%. Conclusion Although the incidence of abnormal genotypes in Y-STR typing is not high, there is still a certain proportion. Therefore, careful treatment should be taken in forensic work. Adding more STR loci is helpful for the correct judgment and analysis.