ITO法和判别函数法在同胞关系鉴定中的应用

目的探讨ITO法和判别函数法在全同胞、半同胞关系鉴定中的应用价值。方法根据500对全同胞、50对半同胞及500对无关个体的15个STR基因座（PowerPlex^TM 16体系）的分型结果，采用ITO法分别计算全同胞关系指数（FSI）、半同胞关系指数（HSI）及其比值（FSI：HSI）。比较三组配对个体的等位基因匹配情况，计算分型结果全不同的基因座数（x0）、半相同的基因座数（x1）和完全相同的基因座数（x2），利用SPSS 13．0分析软件建立全同胞、半同胞和无关个体的判别函数。结果（1）以FSI≥19、FSI〈1作为全同胞与无关个体的判别标准，交互准确率为96.4％；以HSI≥19、HSI〈I作为半同胞与无关个体的判别标准，交互准确率为85.3％；以FSI：HSI≥1、FSI：HSI〈1作为全同胞与半同胞的判别标准，交互准确率为87．5％。（2）分别建立了全同胞-半同胞-无关个体、全同胞-无关个体、半同胞-无关个体、全同胞-半同胞4组判别函数．判别函数交互准确率为84．4％～97．7％，其中同胞-无关个体判别准确率最高。结论ITO法与判别函数法在全同胞、半同胞鉴定中均具有较高的应用价值。

Application of ITO Method and Discriminant Functions in Full Sibling and Half Sibling Identification

Objective To investigate the application of ITO method and discriminant functions method in full sibling and half sibling identification. Methods Five hundred pairs of full siblings（FS）, 50 pairs of half siblings（HS） and 500 pairs of unrelated individuals（UR） were genotyped by PowerPlex^TM 16 system. Full sibling index（FSI）, half sibling index（HSI） and the FSI：HSI ratio were calculated with ITO method. Allelic matching of each pair of the three groups was compared. The locus numbers of no-allele sharing （x0）, half-allele sharing（x1） and two-alleles sharing（x2） were calculated, respectively. The discriminant functions about full-siblings, half-siblings and unrelated individuals（UR） were established by SPSS 13.0 statistical software. Results （1） Regard FSI≥ 19 or FSI〈1 as the standard of distinguishing full sibling from unrelated individual, the alternate correct percentage was 96.4%. Regard HSI≥19 or HSI〈1 as the standard of distinguishing half sibling from unrelated individual, the alternate correct percentage was 85.3%. Regard FSI：HSI≥1 or FSI：HSI〈1 as the standard of distinguishing full sibling from half sibling, the alternate correct percentage was 87.5%. （2） Four groups of discriminant functions were established. The alternate correct percentage of these discriminant functions were 84.4%-97.7%, with the highest one in full sibshipunrelated individual group. Conclusion Both ITO method and discriminant functions method are efficient in identification of full sibling or half sibling.