遗传性先天性白内障与αA-晶体蛋白基因相关性研究

目的 分析遗传性先天性核性和绕核性白内障与定位于21q22．3的αA-晶体蛋白（CRYAA）基因之间的关系。同时对比单链构象多态性（SSCP）和变性高效液相色谱法（DHPLC）两种方法检测单核苷酸多态性（SNP）。方法 用PCR方法扩增CRYAA基因的3个外显子，分别用SSCP和DHPLC两种方法分析扩增产物，对异常者进行DNA测序，寻找基因变异情况。结果用SSCP分析15个样本，未见异常条带；同时用DHPLC检测15个样本，其中1个样本出现双峰，将该样本扩增产物测序鉴定，发现在5’端第6个核苷酸为G／A杂合，二者是同一氨基酸的2个密码子，该核苷酸为CRYAA基因的多态性位点。未发现该基因突变。结论 实验中未发现15例先天性白内障患者与CRYAA基因之间有关联。应用SSCP与DHPLC同时分析，DHPLC检测出1个多态性位点。DHPLC对杂合子检出的敏感性要高于SSCP。

Screening the gene CRYAA with congenital cataract

Objective To screen possible disease-causing gene CRYAA with 15 cases of congenital cataract.At the same time,applg the method of DHPLC to find the novel SNP sites.Methods Amplified the 3 exons of the gene CRYAA by PCR.And applied the SSCP and DHPLC methods to analyse the gene CRYAA in 15 congenital cataract patients and sequenced the aberrant cases.Results No disease-causing mutation was found in the CRYAA gene of the 15 patients.No abnormal case was found by SSCP,but one in the first exon by DHPLC.Then,a nucleotide transform G-A was found at the 6th nucleotide of this exon by sequencing.The amino acid they coded was the same.It was an SNP site.Conclusion We do not find the mutation in the CRYAA gene of the 15 congenital cataract patients,but we find a single nucleotide polymorphism(SNP) in the 6th nucleotide of the first exon of this gene by DHPLC.And DHPLC is the more efficient method in screening genes.