Department of Forensic Medicine, College of Basic Medicine, Central South University, Changsha 410013, China.
Fa Yi Xue Za Zhi. 2023 Jun 25;39(3):288-295. doi: 10.12116/j.issn.1004-5619.2023.530101.
To investigate the efficacy of different numbers of microhaplotype (MH) loci and the introduction of different reference samples on the identification of full sibling, half sibling and differentiation between full sibling and half sibling kinships, and to explore the effect of changing mutation rate on sibling testing.
First, a family map involving three generations was established, and four full sibling identification models, five half sibling identification models and five models distinguishing full and half siblings were constructed for different reference samples introduced. Based on the results of the previous study, two sets of nonbinary SNP-MH containing 34 and 54 loci were selected. Based on the above MH loci, 100 000 pairs of full sibling . unrelated individuals, 100 000 pairs of half sibling . unrelated individuals and 100 000 pairs of full sibling . half sibling were simulated based on the corresponding sibling kinship testing models, and the efficacy of each sibling kinship testing model was analyzed by the likelihood ratio algorithm under different thresholds. The mutant rate of 54 MH loci was changed to analyze the effect of mutation rate on sibling identification.
In the same relationship testing model, the systematic efficacy of sibling testing was positively correlated with the number of MH loci detected. With the same number of MH loci, the efficacy of full sibling testing was better than that of uncle or grandfather when the reference sample introduced was a full sibling of A, but there was no significant difference in the identification efficacy of the four reference samples introduced for full sibling and half sibling differentiation testing. In addition, the mutation rate had a slight effect on the efficacy of sibling kinship testing.
Increasing the number of MH loci and introducing reference samples of known relatives can increase the efficacy of full sibling testing, half sibling testing, and differentiation between full and half sibling kinships. The level of mutation rate in sibling testing by likelihood ratio method has a slight but insignificant effect on the efficacy.
研究不同数量的微单倍型（MH）位点和引入不同参考样本对全同胞、半同胞鉴定以及全同胞和半同胞亲缘关系区分的影响，并探讨突变率变化对同胞关系检测的影响。
首先建立一个包含三代人的家系图谱，并为引入的不同参考样本构建了四个全同胞鉴定模型、五个半同胞鉴定模型和五个全同胞和半同胞区分模型。基于之前的研究结果，选择了两组包含 34 个和 54 个位点的非二进制 SNP-MH。基于上述 MH 位点，根据相应的同胞关系检测模型模拟了 100000 对全同胞、无关个体，100000 对半同胞、无关个体和 100000 对全同胞、半同胞。在不同阈值下，通过似然比算法分析每种同胞关系检测模型的效果。改变 54 个 MH 位点的突变率，分析突变率对同胞鉴定的影响。
在相同的关系检测模型中，同胞检测的系统效能与检测到的 MH 位点数量呈正相关。在相同数量的 MH 位点下，当引入的参考样本是 A 的全同胞时，全同胞检测的效能优于叔伯或祖父，但引入的四种参考样本在全同胞和半同胞区分检测中的鉴定效能无显著差异。此外，突变率对同胞关系检测的效能有轻微影响。
增加 MH 位点数量和引入已知亲属的参考样本可以提高全同胞检测、半同胞检测以及全同胞和半同胞亲缘关系区分的效能。似然比法检测同胞关系时，突变率水平对效能有轻微但无显著影响。
