Abstract:

Objective To evaluate the risk of false identification of sibling relationship. Methods In a case， the samples were analyzed by typing autosomal STR loci and X-chromosomal STR（X-STR） loci. The full sibling index was calculated with the ITO method， as well as the number of identical allele， and the matched STR loci with identical alleles. Results Both the autosomal STR and X-STR genotyping results suggest that the tested persons be not the claimed full siblings. With the non-full-sibling individual ruled out， the full sibling relationship between the dubious individual and the tested full siblings were excluded based on the deduced genotypes of the biological parents. Conclusion Regarding to the sibling identification case， if the sample of biological father or mother is not available， different genotyping technologies （autosomal STR， X-STR，Y-STR， mtDNA etc.） should be used to verify the claimed “full sibling relationship”. The case could also be analyzed by calculating the full sibling index according to the ITO method or counting the number of identical alleles and matched STR loci with identical alleles in order to confirm the identification results mutually and reduce the risk of false conclusion.

Key words: forensic genetics, short tandem repeat, sibling relation

摘要：

目的 考察同胞认亲案件鉴定中的风险。方法 在一例同胞关系鉴定中，采用常染色体STR检测系统及X染色体STR检测系统进行基因型分型，并用ITO法计算全同胞指数及统计共有等位基因数和全相同基因座数进行判定。结果 在该案例中，常染色体STR分型结果与X染色体STR分型结果均提示被检验同胞之间并非其声称的全同胞关系，在排除其中非全同胞个体后，对剩余全同胞进行基因型分析从而反推出其生父母基因型，并与被认个体进行基因型比对后得出排除结论，即被认个体与被检验同胞之间不存在生物学全同胞关系。结论 对于同胞认亲的案件，若无父亲和（或）母亲参与，鉴定人应尽可能地通过多种检测系统（常染色体STR、X-STR、Y-STR、mtDNA等）综合分析，从而对被检验同胞所声称的“全同胞”关系进行验证；也可用ITO法计算全同胞指数及统计共有等位基因数和全相同基因座数进行判定，这样可以互相印证鉴定结果，降低误判风险。

关键词: 法医遗传学, 短串联重复序列, 同胞关系