依据共有STR基因座数判别全同胞关系

Full Sibling Identification Based on the Number of Matched STR Locus

目的建立并探讨基于共有STR基因座数的全同胞关系判别方法。方法根据280对全同胞(fullsibling,FS)及2 003对无关个体(unrelated individual,UI)Identifiler系统15个STR基因座的分型结果,采用计数法计算全不同基因座数(A0)、半相同基因座数(A1)和全相同基因座数(A2),依据ITO法计算每对受试者的全同胞指数(FSI),应用判别分析得出基于共有基因座数或FSI进行全同胞及无关个体关系判别的Fisher判别函数,并比较其判别效能。结果全同胞对中的A1、A2和无关个体对中的A0、A1均呈正态分布,全同胞对中的A0和无关个体对中的A2均呈偏态分布。A1在两组人群中的分布差异无统计学意义(P>0.01)。同时采用A0和A2建立的全同胞及无关个体关系的判别函数分别为ZFS=0.99817A0+4.24442A2-12.77970和ZUI=2.014 56 A0+1.546 58 A2-7.280 76。采用上述判别函数进行全同胞及无关个体关系判别的平均错判率为0.049 0。上述判别函数的判别效能与基于FSI的判别函数的判别效能差异无统计学意义。结论可以采用Identifiler系统的共有基因座数进行全同胞及无关个体关系的判别,所建立的判别公式的判别效能与经典ITO法相近。

Objective To establish and evaluate the method of matched locus numbers in full sibling identification. Methods Two hundred and eighty full sibling（FS） pairs and 2003 unrelated individual（UI） pairs were genotyped with Identifiler system. The number of locus matched with 0 identical allele（A0）, matched with 1 allele（A1） or matched with 2 alleles（A2） were counted and full sibling index（FSI） were calculated based on ITO method. Fisher discriminant functions were established based on the numbers of matched STR locus or FSI. Power of different Fisher discriminant functions was statistically analyzed. Results The distribution of A1 and A2 in FS group and that of Ao and A1 in UI group were in accord with normal distribution. Contrarily, Ao in FS group and A2 in UI group fitted to skew distribution, respectively. Difference of A1 distribution was not statistically significant in the two groups（P〉0.01 ）. The established Fisher discriminant functions based on A0 and A2 for each group were ZFS=0.998 17 A0＋4.24442 A2-12.77970 and ZUI=2.014 56 A0＋1.546 58 A2-7.280 76, respectively, the average error probability of which was as low as 0.049 0. The power of discrimination for full sibling showed no statistically significant difference between ITO method and the established Fisher discriminant functions. Conclusion The number of matched STR locus in Identifiler system is a valuable method in full sibling identification. The discriminating power of the estab- lished Fisher discriminant functions based on the matched STR locus number is similar with that of classic ITO method in full sibling identification.