Objectives: To study the detection efficiency of trio full sibling with another known full sibling reference added under different number of autosomal STR typing systems.
Methods: Based on 43 detection systems consisting of 13 to 55 representative autosomal STR loci, 10 000 true families (full sibling group) and 10 000 false families (unrelated individual group) were randomly simulated. The full sibling index (FSI) was calculated based on the method of family reconstruction. The cumulative sibling relationship index (CFSI) of 0.000 1 and 10 000 were used as the evaluation thresholds, and the detection efficiency parameters were calculated and compared with the identification of the duo full sibling testing.
Results: With the increasing number of STR loci, the error rate and inability of judgement rate gradually decreased; the sensitivity, specificity, correct rate of judgment and other parameters gradually increased, and the system efficiency gradually improved. Under the same detection system, trio full sibling testing showed higher sensitivity, specificity, system efficiency and lower inability of judgement rate compared with duo full sibling testing. When the system efficiency was higher than 0.85 and inability of judgement rate was less than 0.01%, at least 20 STRs should be detected for trio full sibling testing, which was less than 29 STRs required by duo full sibling testing.
Conclusions: The detection efficiency of trio full sibling testing is superior to that of duo full sibling testing with the same detection system, which is an effective identification scheme for laboratories with inadequate detection systems or for materials with limited conditions.
目的: 研究不同数目常染色体STR分型体系下增加另一已知全同胞个体的三个体组合全同胞关系鉴定的检测效能。方法: 基于13~55个代表性STR基因座构成的43种检测体系，随机模拟产生10 000个真家系（全同胞组）和10 000个假家系（无关个体组），基于家系重建法计算全同胞关系指数，以累积全同胞关系指数为0.000 1和10 000作为评判阈值，计算各检测效能参数，并与两个体组合全同胞关系鉴定比较。结果: 随着STR基因座数目递增，判断错误率、无法判断率逐渐减小，灵敏度、特异度、判断正确率等参数逐渐增大，系统效能逐渐提升。同一检测体系下，与两个体组合相比，三个体组合的灵敏度、特异度较高且无法判断率较低，系统效能较高。要求系统效能高于0.85且判断错误率低于0.01%时，三个体组合至少需检测20个STR，少于两个体组合（29个STR）。结论: 同一检测体系下三个体组合全同胞关系鉴定的检测效能优于两个体组合，对检测体系储备不足的实验室或者条件受限的检材是有效的鉴定方案。.
Keywords: autosome; detection efficiency; forensic genetics; short tandem repeats; trio full sibling testing.