论文部分内容阅读
目的 探讨短串联重复序列 (short tandem repeats,STRs)遗传变异的方式及机理。方法用银染方法对 3个 STR位点 (FGA、D12 S391、D11S5 5 4 )共 19个发生突变的家系父、母、子的 DNA样本进行 STR基因分型 ,将需测序的等位基因条带从凝胶上切下 ,再进行 PCR扩增 ,产物经纯化作为测序模板 ,采用循环测序法测序。结果 19个家系中有 18个家系子代新产生的等位基因变异表现为一个重复单位的增加或减少 (表现为一个重复单位增加的有 8个家系 ,减少的有 7个家系 ,不确定的有 3个家系 ) ,只有 1个家系表现为 2个重复单位的减少。子代新产生的等位基因来自父亲的有 13个家系 ,来自母亲的有 3个家系 ,不能确定的有 3个家系。来自父与母的比例约为 4∶ 1。 3个 STR位点等位基因突变都出现在长的、连续的四核苷酸重复区 (FGA的“CTTT”区、 D12 S391的“AGAT”区、 D11S5 5 4的“AAAG”区 )。结论FGA、D12 S391和 D11S5 5 4 3个 STR位点的等位基因突变主要表现为一个重复单位的增加或减少占95 % ,其次是两个重复单位的变化 ,没有碱基的插入或缺失。突变主要来自父亲。在这 3个 STR位点中的长的、连续的四核苷酸重复区可能是等位基因突变的敏感点
Objective To explore the ways and mechanism of genetic variation of short tandem repeats (STRs). Methods The genotypes of 19 parental, maternal and pedigree DNA samples from 3 STR loci (FGA, D12 S391, D11S5 5 4) were genotyped by silver staining. The alleles The band was excised from the gel, and PCR amplification was performed. The product was purified as a sequencing template and sequenced by cycle sequencing. RESULTS: Allelic variation in alleles produced by 18 offspring in 19 pedigrees was shown as an increase or decrease in one repeat unit (expressed as an increase in one repeat unit of 8 pedigrees, a decrease of 7 pedigrees, an indefinite There are three families), only one family showed a reduction of two repeat units. The newly generated alleles of the offspring come from the father of 13 families, from the mother of 3 families, not sure of 3 families. The ratio of father to mother is about 4: 1. All three STR loci alleles were found in long, continuous tetranucleotide repeat regions (“CTTT” region of FGA, “AGAT” region of D12 S391, and “AAAG” region of D11S5 5 4). Conclusion The allelic mutations of FGA, D12 S391 and D11S5 543 STR loci are mainly characterized by 95% increase or decrease of one repeat unit, followed by two repeat units, with no insertion or deletion of base. The mutation is mainly from the father. The long, contiguous tetranucleotide repeat region among these three STR sites may be a sensitive point of allelic mutation