先天性粉尘状白内障一家系基因突变定位

Gene mapping in a Chinese family with autosomal dominant centralpuiverulent cataract

目的探讨先天性粉尘状白内障一家系的基因突变定位。方法回顾性研究。对一先天性白内障家系成员（共32人，其中患者15人）散瞳后采用裂隙灯显微镜观察晶状体，并取外周血提取DNA样品。选取常染色体上微卫星标记物，通过聚合酶链反应（PCR）进行扩增后，进行基因扫描。利用GeneMapper软件进行PCR扩增产物片段大小和单体型分析。分别通过Linkage5．1和GeneHunter软件进行两点法和多点法对数优势记分（LOD）值计算。对候选基因通过测序进行基因序列分析。结果家系成员中的白内障患者晶状体环胎儿核可见散在的类似于蚁卵的短棒状混浊。在不同患者间以及同一患者的不同眼别存在晶状体混浊程度和形态的差异。两点法计算LOD值，在重组率（0）为0时，微卫星位点D20S186、D230S163、D20S915、D20S152、D20S98、D20S904、D20S875、D20S112、D20S1140、D20S432均获得正值，其中在D20S904获得最大LOD值6．02。通过单体型构建，发现微卫星位点D20S163在Ⅳ7患者发生交换，而D20S912在Ⅱ3患者发生交换。基因序列分析未发现BFSP1、PLCB4基因突变。结论该家系突变基因位于常染色体20p12．1-p11．23上微卫星位点D20S186和D20S912间5．47厘摩范围内。

Objective Mapping the mutation gene for a Chinese family with autosomal dominant cataract. Methods It was a retrospective study. Thirty-two individuals in this family, including fifteen patients, eight normal siblings and nine spouses, were investigated and 8 ml blood was collected from each member under informed consent. Genomic DNA of all 29 members was isolated by standard protocol. A genome wide scan was performed after PCR amplification for microsatellite makers on autosomal chromosomes. LOD score was calculated by Linkage 5. 1 and GeneHunter software. Results Positive Lod score were obtained in 10 microsatellite makers （D20S186, D20S163, D20S915, D20S152, D20S98, D20S904, D20S875, D20Sl12, D20Sl140, D20S432） on chromosome 20q, and the maximum LOD score with D20S904 was 6. 02. Conclusions Haplotype construction and multipoint analysis mapped the mutation gene in this inherited cataract family to the chromosome 20p12. 1-20p11.23 region between D20S186 and D20S912, which is an approximately 5.47 centimorgan length. This is the second congenital cataract locus linked to chromosome 20q .