Abstract:

Objective Strategies for special duos paternity testing were explored through combination detection of autosomal STR with X-chromosomal STR loci. Methods Genomic DNA was extracted from six blood stain samples from three duos cases numbered 1，2 and 3 respectively. Thirty nine autosomal STR loci were genotyped by Goldeneye 20A kit and AGCU21+1 kits， and sixteen X-chromosomal STR loci were simultaneously genotyped by in-house amplification system. Results One contradictory locus in each case appeared through genotyping by Goldeneye 20A kit. When the total number of detected STR loci were increased to thirty nine， three contradictory loci were found in case No.1， so it was excluded that the father was the biological father. There was no new contradictory locus in case No.2 and case No.3. X-STR genotyping results showed that there were 8 contradictory loci in case No.1， and no contradictory locus in case No.2 and No.3. So the X-STR typing results were consistent with the autosomal STRs results. Conclusions To special duos cases with only one locus mismatch， combination typing of new autosomal STRs and X-chromosomal STRs can be an effective way to make the identification conclusion reliable.

Key words: forensic genetic, paternity testing, STR, X chromosome

摘要：

目的 通过对常染色体和X染色体遗传标记的检测，探讨单亲疑难案例的鉴定策略。方法 提取3个单亲鉴定案例的6份血样，采用Goldeneye ２０Ａ试剂盒和AGCU21+1试剂盒检测常染色体上39个STR基因座，采用自主研制的16重X-STR扩增系统检测X染色体上16个STR基因座。结果 用Goldeneye ２０Ａ试剂盒检测后发现每个单亲案例均有一个基因座不符合遗传规律，当常染色体STR基因座增加到39个时，案例1累计出现3个矛盾基因座；案例2和案例3均没有出现新的矛盾基因座。X染色体STR分型结果显示案例1有8个矛盾基因座，案例2和案例3无矛盾基因座，与常染色体分型结论相符。结论 对于出现单基因座不符合遗传规律的母女、母子、父女单亲案例鉴定，不仅可以增加新的常染色体STR检测，也可以增加X染色体STR的检测，这样在相互验证的同时也能获得更加可靠的鉴定意见。

关键词: 法医生物学, 亲子鉴定, STR, X染色体