无毛囊发干遗传分析新标记的应用

Application of new markers in genetic analysis for hair stem without follicles

目的解决法医检验工作中自然脱落的毛发、严重降解的骨骼及牙齿这类检材检验难度大且检出完整DNA分型的成功率低的问题。方法应用一类特殊的DNA序列——逆转座子(retrotransponson,RE)进行检验鉴定,用作遗传分析的RE DNA片段长度多在60~125 bp,利用21个基因座组合的RE个体识别系统计算似然比(likelihood,LR),并计算亲缘关系鉴定中的累计非父排除率(combined paternity index,CPI)。结果本系统对无毛囊的发干、严重降解的生物检材有较高的检出成功率,LR值多在10~8~10^(12),完全能够达到同一认定的水平。计算CPI值后发现难以得出支持假设的结论,多个案例计算的CPI数值小于10 000。结论 21个基因座的RE系统可以用于个体识别鉴定,亲缘关系的鉴定仍需增加基因座。

Objective To solve the problems of low success rate in detecting complete DNA typing of biological samples, such as naturally fallen hair, severely degraded bones and teeth which is difficult in forensic identification. Methods We applyed a specific retrotransposon （RE） DNA sequences in identification,with DNA fragment length of 60 - 125 bp. A RE combined with 21 loci were used in individual discrimination to compute the likelihood （LR） values and combined paternity index （CPI） values in phylogenetic identification. Results This research obtained high success rate in detection of hair stem without follicles and severely degraded biological samples. We found that most of the LR values were 10^8 - 10^12 ,which met the requirement of identity establishing. Through the CPI values,it was difficult to support the assumptions,with most of the CPI values less than 10 000. Conclusions The RE with 21 loci can be used for individual discrimination, but more loci are need for applying in phylogenetic identification.