X染色体Amelogenin等位基因缺失的研究

目的 探讨采用Amelogenin基因常规Sullivan106/112 bp体系进行性别鉴定时X染色体Amelogenin等位基因片段(Amel-X)缺失的原因以及缺失后对法医物证性别鉴定和临床疾病诊断的影响.方法 采用Sullivan212/218 bp和Haas-Rochholz80/83 bp引物体系对Amel-X缺失的样本进行验证,并对缺失的Amel-X进行序列分析.结果 采用Sullivan212/218 bp和Haas-Rochholz80/83 bp引物体系分型时均可重获缺失的等位基因.测序分析在Sullivan106/112 bp体系的正向引物结合区检出3种点突变,包括分别位于3'端第2位、第13位的单点突变以及第2位和第13位同时发生的杂合多点突变.结论 引物结合区点突变导致的无效扩增是Amel-X等位基因缺失的原因,这在实践中会干扰性别鉴定,需引起重视.

Allelic dropout of amelogenin gene on X chromosome

Objective To investigate the mechanism that cause allelic dropout of amelogenin gene on X chromosome(Amel-X)when using routine Sullivan106/112 bp primer set in sex identification and discuss its influence on the forensic sex identification and the clinical diagnosis.Methods Amel-X dropout was validated with Sullivan212/218 bp and Haas-Rochholz80/83 bp primer sets.Amplification of amelogenin gene was used to analyze dropout of the Amex-X followed by sequencin.Results Sullivan212/218 bp and Hgas-Rochholz80/83 bp primer sets could be used to identify gender correctly.Three types of point mntation were observed in the forward primer binding region of the Sullivan106/112 bp primer set by sequencing in the lost Amel-X,including single point mutation at 2nd and 13th sites,respectively,and heterozygous multiple point mutations at 2nd and 13th sites.Conclusions Point mutation in the primer binding region may result in a failure to amplify amelogenin allele and thus lead to a null allele.This finding should be mid attention to because it may interfere with the sex identification.