重复顺序多态性及基因剂量分析诊断迪谢内及贝克肌营养不良基因携带者

Carrier detection in families of Duchenne and Becker muscular dystrophy by methods of repeat sequence polymorphism and gene dosage analysis

目的 在 18个缺失型迪谢内及贝克肌营养不良家系中 ,比较有效检测基因携带者的方法。方法 用多重聚合酶链反应方法扩增dystrophin基因 9个外显子 ,检测先证者有无外显子缺失 ;用聚合酶链反应方法扩增dystrophin基因内含子及 5′和 3′端的短串联重复顺序 ,对先证者及家族成员进行扩增片段长度多态性分析 ;用基因剂量分析方法判断女性亲属相关外显子的基因组靶序列的原始拷贝数。结果 在 18个肌营养不良家系中检测到外显子或重复顺序片段缺失 ,在 17个家系中得到女性亲属重复顺序片段 ,通过分析识别了 2组纯合、6组杂合和 11例半合状态的重复顺序片段。对11个缺失型家系的女性亲属进行基因剂量分析 ,确定了 9例女性为缺失基因携带者。结论 重复顺序多态性与基因剂量分析结合可有效地检测缺失型迪谢内和贝克肌营养不良的女性携带者。

Objective To develop and compare the methods for determining the carrier status in the 18 deleted families of Duchenne and Becker muscular dystrophy. Methods Deletion analysis of the probands was performed by multiplex polymerase chain reaction (PCR) to amplify 9 dystrophin exons described by Chamberlain. Polymorphism linkage analysis was made on DNA with PCR amplification using primers of intragenic short tandem repeat sequences (STR44, STR45, STR49 and STR50), primers of 5′ end (5′DYS II) and primers of 3′end (MZ18, MZ19) in the members of the families. Gene dosage analysis was performed and DQ value was calculated. Results Both of deletions of exons and STR allelic fragments adjacent to the deleted exons were determined in the probands. STR allelic fragments of 6 pairs of heterozygotes, 2 pairs of homozygotes and 11 hemizygotes were detected at those loci in all of the female relatives. 13 female relatives in deleted families were assayed with gene dosage analysis. In 9 /13 female relatives DQ value was in the range of single copy and carrier status was ascertained.Conclusion Repeat sequence polymorphism as well as gene dosage analysis can potentially be used in carrier detection in the deleted families of Duchenne and Becker muscular dystrophy.