进行性肌营养不良基因中一个新的P20/MspI多态性位点

A NEW Msp I POLYMORPHISM FOR THE DYSTROPHIN INTRAGENIC PROBE P20 (DXS269)

应用进行性肌营养不良(DMD)基因内一个融合片段P20(DXS269)为探针对MspI位点进行限制性片段长度多态性(RFLP)分析,除检出文献报道的一组多态性片段外,发现了一个新的MspI多态性位点。该位点主要等位片段长度长1.9kb,频率0.736,次要等位片段长2.2 kb。由这两个多态性位点构成4种单元型,能提供的多态性信息量(polymorphic-mformation contents,PIC)为0.621。该新位点在日本人中也存在,可能为东方人所特有。此发现再次提示DNA序列存在种族差异。

P20 (DXS269) is a 2.65 kb Pst Ⅰ insert in pKUN_1. The insert consists of 2 genomic Pst Ⅰ fragments originally separated by 32.5 kb of genomic sequences. When this probe was applied to RFLP linkage analysis in Chinese, a new Msp Ⅰ polymorphic site was found in addition to the one reported previously in Caucasinas. The frequencies for the new alleles (2.2 kb and 1.9 kb) were 0.763 and 0.237, respectively. This polymorphism was observed in Japanese too, and might be specific in Oriental populations.