短串联重复序列基因座等位基因丢失现象的研究  

Analysis of allelic drop-out at short tandem repeat loci

作　　者：陈文静[1] 李越[2] 吴小洁 张胤鸣[1] 刘素娟[1] 陈勇[1] 陈维红[1] 孙宏钰[1] 

机构地区：[1]中山大学中山医学院法医物证学教研室,广州510080 [2]广州市刑事科学技术研究所 [3]清远市公安局

出　　处：《中华医学遗传学杂志》2012年第3期360-363,共4页Chinese Journal of Medical Genetics

基　　金：基金项目：高校基本科研业务费中山大学青年教师培育项目（09YKPY78）;清远市科技计划项目（2010A002）

摘　　要：目的探讨用PowerPlex16体系短串联重复（shorttandemrepeat，STR）基因座分型时等位基因丢失的现象及原因。方法分析10642宗肯定亲权的亲子鉴定案件（涉及18314次减数分裂），对PowerPlex16体系疑似发生等位基因丢失的样本采用Identifiler^TM体系和单基因座引物体系进行验证，分离丢失的等位基因，并进行DNA序列测定和比对。结果在D18S51、D21S11、FGA和TPOX等4个基因座上，共确认了8宗等位基因丢失案例。通过测序均在PowerPlex16体系引物结合区检见单碱基变异，包括D18S51发生4例，其中2例重复序列上游第79位碱基G—A转换，1例下游162位G—T颠换和1例上游74位G—C颠换；D21S11发生2例，分别为重复序列上游第17位C—A颠换和12位A—G转换；FGA和TPOX各发生1例，分别为重复序列下游142位G—A转换和下游第198位G—A转换。等位基因丢失的总发生率为0．437×10^-3。结论引物结合区的碱基变异可能导致扩增失败，产生等位基因丢失。在怀疑发生等位基因丢失时，应采用不同的引物体系进行验证以获得准确分型。在亲子鉴定结果判别和个体识别数据交换中需对此加以重视。Objective To explore the cause for allelic drop-out at short tandem repeat （STR） loci upon paternity testing with a PowerPlex 16 kit. Methods A total of 10 642 DNA-confirmed paternity testing cases （18 314 parent/child allelic transfers） were analyzed with the PowerPlex 16 kit. Samples suspected for having allelic drop-out were verified with an IdentifilerTM kit and/or locus-specific singleplex amplification systems. PCR products of null alleles were separated and directly sequenced. Results Eight cases of allelic drop-out were found. The overall rate of null allele in the PowerPlex 16 system was 0. 437 × 10-3. DNA sequencing has confirmed single base variations within the binding region of published primers, in which 4 cases involved the D18S51 locus （2 cases with G〉A transitions at 79 bp upstream of the repeats, 1 case with G〉T transversion at 162 bp downstream of the repeats and 1 case with G〉C transversion at 74 bp upstream of the repeats）, 2 cases involved the D21Sll locus （1 case with C〉A transversion at 17 bp upstream of the repeats and 1 case with A〉C- transition at 12 bp upstream of the repeats）. One case involved the FGA locus （1 case with G〉A transition at 142 bp downstream of the repeats） and 1 case involved TPOX locus （1 case with G〉A transition at 198 bp downstream of the repeats）. Conclusion Base variation in the primer binding region may cause failed PCR and result in null allele reports. Alternative primer sets should be used to verify the suspected allelic drop-out. Attention should be paid to this during paternity testing and data exchange for personal identification.

关 键 词：短串联重复 等位基因丢失 碱基变异 亲子鉴定 个体识别 

分 类 号：R394[医药卫生—医学遗传学]