二联体亲子鉴定罕见案例分析及应对策略

Analysis and solution of a rare case of parentage testing of duos

目的对亲子鉴定中二联体罕见案例进行分析并给出应对策略。方法对罕见案例样本进行DNA提取,使用AGCU EX-22试剂盒进行二联体和三联体检测;使用阅微基因36A试剂盒进行二联体检测。通过遗传测序仪进行电泳分析,GeneMapper ID-X软件进行数据分析得到短串联重复序列(short tandem repeats,STR)图谱和相应的基因座数据,并计算其累积亲权指数。结果采用AGCU EX-22试剂盒进行被检父和孩子二联体鉴定,获得累积亲权指数为7.0516×10^(2),这个值既大于0.0001又小于10000。根据《亲权鉴定技术规范》(GB/T 37223-2018),其结果是既不支持、又不能排除被检父为孩子的生物学父亲,不能出具明确的鉴定意见;增加孩子母亲样本,改为三联体鉴定后,使用相同的试剂盒进行鉴定,获得的累积亲权指数为2.6327×10^(8),大于10000,支持被检父为孩子的生物学父亲。与此同时,增加STR基因座位点,使用阅微基因36A试剂盒进行被检父和孩子的二联体鉴定,获得累积亲权指数为1.0378×10^(9),同样大于10000,亦能出具明确的鉴定意见。结论在二联体亲子鉴定中,通过增加孩子生母做三联体亲子鉴定或者是增加STR位点进行检测,都能提高累积亲权指数,帮助罕见疑难亲子鉴定案例出具明确的鉴定意见。

Objective This study aimed to explore an efficient method in a rare case of parentage testing of duos.Method DNA extraction was performed on rare case samples,and parentage testing of duos and trios was performed using AGCU EX-22 Kit,and par⁃entage testing of duos was also performed using Microreader 36A Kit.The electrophoretic analysis was conducted in the genetic ana⁃lyzer.Then the data were analyzed with GeneMapper ID-X to get STR profiling and corresponding locus data,and the combined parent⁃age index(CPI)was calculated.Results Father-child parentage testing of duos was conducted using AGCU EX-22 Kit.The CPI result was 7.0516×10^(2),greater than 0.0001 yet less than 10000.According to the"Specification of Parentage Testing"(GB/T 37223-2018),the CPI result neither supported the conclusion that the tested father was the biological father of the tested child,nor did it eliminate this possibility.Therefore,it was not possible to express a clear opinion on this parentage testing of duos.In this case,the DNA sample of the tested child's mother was added in the parentage testing of duos which was changed into a parentage testing of trios using the same test⁃ing kits.The CPI of the revised test was 2.6327×10^(8),greater than 10000.This result was positive that the tested father was the biologi⁃cal father of the tested child and a definite opinion of parentage testing could be issued.At the same time,the number of STR loci was increased and the father-child parentage testing of duos was conducted using the Microreader 36A Test Kit.The CPI value was 1.0378×10^(9),greater than 10000.Thus,a definite parentage opinion could be issued.Conclusion In parentage testing of duos,either by add⁃ing the child's biological mother for aparentage testing of trios or by adding the STR loci for testing,could improve the CPI and help to produce a definitive identification opinion in rare and difficult parentage testing.