温州地区人群21个STR基因座的突变情况分析

Mutation analysis of 21 STR loci in Wenzhou population

目的:观察和分析温州地区人群21个常染色体STR基因座的突变情况及其特征。方法:收集9418例支持亲权关系的亲权鉴定案件共21200个样本,采用AGCU EX22人类荧光标记STR复合扩增检测试剂进行扩增,比较各基因座的突变率和突变等位基因的亲代来源、片段大小、突变步数及重复单位的增减比例、方向的频次,分析突变各相关因素之间的相互关系。结果:9418例亲子鉴定中共发现314例突变,观察到319个突变事件;21个基因座中,观察到20个基因座发生突变,突变率为0.08‰~3.48‰,各基因座突变率间差异无统计学意义(χ^(2)=29.77,P>0.05);父源突变与母源突变的比例为4.78:1,父源等位基因发生突变的概率总体上大于母源等位基因发生突变的概率,差异有统计学意义(t=4.55,P<0.05);父源突变和母源突变出现重复单位增加、减少与不确定3种频次的差异无统计学意义(χ^(2)=0.28,P>0.05);一步突变与二步及以上突变中出现的重复单位增加、减少与不确定3种频次的差异具有统计学意义(χ^(2)=7.22,P<0.05);短、中、长片段等位基因突变出现的重复单位增加、减少与不确定3种频次的差异具有统计学意义(χ^(2)=26.81,P<0.05)。结论:常染色体STR基因座等位基因突变现象较为常见,在法医学亲权鉴定和DNA寻亲数据库建设中应引起注意。

Objective:To analyze the mutation situation and characteristics of 21 STR loci in Wenzhou population.Methods:A total of 21200 samples from 9418 paternity testing cases supporting parental relationship were collected and amplified with AGCU EX22 human fluorescent labeled STR multiplex amplification kit.The mutation rate of each locus and the source,fragment size,mutation steps and the increase or decrease of repeat units of mutant alleles were counted,and the correlation between mutation factors was analyzed.Results:In 9418 paternity tests,314 mutations cases and 319 mutation events were observed.Mutation was observed in 20 loci out of 21,with the mutation rate ranging between 0.08‰and 3.48‰,and there was no significant difference in the mutation rate among each locus(χ^(2)=29.77,P>0.05).The ratio of paternal mutation to maternal mutation was 4.78:1,and the mutation probability of paternal allele was generally greater than that of maternal allele,showing statistical difference(t=4.55,P<0.05).There was no significant difference in the increase,decrease and uncertainty of repeat units between paternal mutation and maternal mutation(χ^(2)=0.28,P>0.05).There was significant difference in the increase,decrease and uncertainty of repeat units between one-step mutation and two-step or more mutations(χ^(2)=7.22,P<0.05).There was statistical difference in the increase,decrease and uncertainty of repeat units in short,medium and long segment allele mutations(χ^(2)=26.81,P<0.05).Conclusion:The allele mutation of STR locus is common,which should be paid attention to in the paternity test and the construction of DNA family search database.