常染色体STR遗传标记在同胞鉴定中的应用

目的 探讨常染色体STR遗传标记用于鉴定两个体同胞关系的可行性。方法 用Power Plex~(TM)16体系15个STR基因座检测150对同胞个体和150对无关个体,ITO法计算同胞关系指数(PI_(FS))与同胞关系概率(W_(FS)),并比较两组W_(FS)值及两个体间等位基因匹配情况的差异,对前者进行组间差异的x~2检验。结果 100对(66.67％)同胞个体的W_(FS)大于0.9995;无关个体W_(FS)均小于0.8,其中100对(66.67％)W_(FS)小于0.27。同胞个体两个体间等位基因全相同的基因座个数为1～10个不等,平均5.49个,无关个体0～5个不等,平均1.33个;等位基因全不同的基因座个数,同胞个体0～6个不等,平均1.66个,无关个体2～11个不等,平均6.57个;等位基因半相同的基因座个数,同胞个体3～13个不等,平均7.85个,而无关个体1～13个不等,平均7.11个。经x~2检验,同胞个体和无关个体间全相同和全不同的基因座数差异均有极显著意义(P<0.001),半相同的基因座数差异无显著意义(P>0.05)。结论 PowerPlex~(TM)16体系可用于鉴定同胞关系。当两个体全不同基因座个数大于或等于6个,或全相同基因座数为0时,提示为无关个体;当两个体全不同基因座个数小于或等于1个,或全相同基因座数大于或等于6个时,提示为同胞。

Application of autosomal STR genetic markers in siblings identification

Objective To discuss the probability of siblings identification by autosomal short tandem repeat (STR). Methods 150 pairs of full siblings and 150 pairs of unrelated individuals were genotyped by the 15 STR loci of Power Plex?6 system. Paternity index of full siblings (Pips) and paternity probability of full siblings (WFS) were calculated with the method of ITO. WFS and allelic matching of the two groups were compared, and three sorts of allelic matching in each pair were tested by chi-square test. Results Wps of 100 pairs of siblings (66.67%) were more than 0.9995; WFS of unrelated individuals were less than 0.8, and that of 100 pairs (66.67%) were less than 0.27. The locus number of the entire-same ranged from 1 to 10, averaged 5.49 in siblings, while in unrelated individuals ranged from 0 to 5 and averaged 1.33; that of the entire-different ranged from 0 to 6, averaged 1.66 in siblings but ranged from 2 to 11 and averaged 6.57 in unrelated individuals; that of the half-same ranged from 3 to 13, averaged 7.85 in siblings, and ranged from 1 to 13, averaged 7.11 in unrelated individuals. By chi-square test, there was significant difference (P<0.001) in the entire-same and the entire-different and unsignificant difference (P >0.05) in the half-same between the two groups. Conclusion It is effective to identify siblings by Power-Plex?6 system. Testing of 15 STR loci of PowerPlex?6 system, it suggested that the pair were unrelated individuals when the locus number of the entirely-different is not less than 6 or that of the entirely-same is zero, and that the pair were siblings when the locus number of entirely-different is not more than 1 or that of the entirely-same is not less than 6.