Objective: To investigate the genetic polymorphisms of 3 short tandem repeat (STR) loci D21S11,D21S1440 and Penta D on chromosome 21 in Tianjin Han population and to provide basic data for the use of 3 STR loci in gene diagnosis and prenatal gene diagnosis of Down syndrome (DS). Methods: Blood samples were collected from 332 unrelated individuals of Tianjin Han population. QF-PCR and ABI PRISM 377 DNA sequencer were used. The frequencies of the genotypes were tested with Hardy-Weinberg equilibrium. Genetic analysis was performed to conclude some data of population genetics such as the frequency of the alleles,the heterozygosity of observation(Ho),the polymorphism information content (PIC),the probability of discrimination power(DP) and the probability of exclusion(PE). Results: Six,four and eight alleles of D21S11,D21S1440 and Penta D were observed respectively. The frequencies of the genotypes were in good agreement with Hardy-Weinberg equilibrium. The Ho of 3 STR loci were 0.617,0.705 and 0.867. The PIC were 0.755,0.596 and 0.795. The DP were 0.916,0.794 and 0.931. The PE were 0.312,0.436 and 0.730. Conclusion: D21S11,D21S1440 and Penta D STR loci had high heterozygosity in Tianjin Han population,which were good genetic markers of chromosome 21 and can be used in gene diagnosis and prenatal gene diagnosis of DS.%目的:研究天津汉族群体21号染色体上D21S11、D21S1440和Penta D 3个短串联重复序列(STR)基因座遗传多态性,为唐氏综合征(DS)基因诊断和产前基因诊断提供实验依据.方法:收集天津无亲缘关系的汉族个体332例,定量荧光PCR(QF-PCR)扩增STR基因座,ABI PRISM 377测序仪检测PCR扩增产物.根据3个STR基因座的基因型分布进行Hardy-Weinberg平衡检验.计算3个STR基因座的基因型频率、观察杂合度(Ho)、多态信息量(PIC)、个体识别率(DP)、非父排除率(PE)等群体遗传学数据.结果:D21S11、D21S1440和Penta D 3个STR基因座分别检出6、4、8个等位基因,基因型分布均符合Hardy-Weinberg平衡定律.3个基因座的Ho分别为0.617、0.705、0.867,PIC分别为0.755、0.596、0.795,DP分别为0.916、0.794、0.931,PE分别为0.312、0.436、0.730.结论:D21S11、D21S1440和Penta D STR基因座在天津汉族群体杂合度高,是21号染色体良好的遗传标记,对DS的基因诊断有指导意义.
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