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目的鉴定一个先天性白内障家系的致病基因。方法根据已知与先天性白内障有关的12个致病基因的染色体上的定位,分别选取3～4个的微卫星标记位点,对该家系进行连锁分析。通过测序鉴定致病基因。结果在1q21.1GJA8位点显示最大Lod值2.44。致病基因定位于1q21.1区的GJA8基因,构成缝隙连接的缝隙连接蛋白Connexin50。DNA序列分析鉴定显示其第2外显子的第191个碱基杂合突变T>G导致其蛋白产物第64位缬氨酸转变为甘氨酸。结论Connexin50的V64G新生突变是导致该家系的致病原因。
Objective To identify the causative genes of a congenital cataract pedigree. Methods According to the chromosomal location of 12 pathogenic genes, which are known to be associated with congenital cataract, three to four microsatellite loci were selected, respectively. The linkage analysis was carried out on this pedigree. Identification of pathogenic genes by sequencing. The result showed a maximum Lod value of 2.44 at the 1q21.1 GJA8 locus. The causative gene is located in the 1q21.1 region of the GJA8 gene, forming a gap junctional connexin connexin50. DNA sequence analysis revealed that the 191st base heterozygous mutation T> G of its second exon resulted in the conversion of the 64th valine in its protein product to glycine. Conclusions Connexin50 V64G neoplasia is the causative agent of this pedigree.