先天性无虹膜症一家系PAX6基因Q310X突变的致病研究

Analysis of PAX6 gene in a Chinese family with congenital aniridia

目的探讨先天性无虹膜症一家系的致病基因突变情况与发病机制。方法采用病例对照研究方法。对该家系所有成员21人进行全面的眼科检查，同时进行家系调查并采集外周血样本，分离单个核细胞；用基因组DNA纯化试剂盒提取基因组DNA，以先证者DNA为模板聚合酶链反应法扩增转录因子PAX6基因全部14个外显子，用双脱氧末端终止法进行测序分析。结果测序结果发现先证者1112的PAX6基因在第11外显子上有Q310X（c．1378C〉T）无义突变。它导致了第301位氨基酸密码子由CAA改变为TAA（Q301X），编码的谷氨酰胺突变为强终止密码子。对该家系中所有21名成员PAX6基因测序，结果发现所有10例患者都携带这一突变，而11名正常人则未检测到这一改变。结论PAX6基因Q310X的无义突变所致PAX6蛋白翻译提前终止是此先天性无虹膜症家系的致病原因。

Objective To explore the pathogenic mutation in a Chinese family with congenital aniridia. Methods It is a case-control study. All 21 members of the family underwent a comprehensive ophthalmic examination and family line investigation. Mononuclear cell was isolated from peripheral blood and genomic DNA was prepared by genomic DNA purification kit. All fourteen exons of the PAX6 gene were amplified by polymerase chain reaction （PCR）from proband＇s genomie DNA. PCR products of each exon were analyzed by direct sequencing. Results A nonsense mutation （Q310X） in exon 11 of PAX6 gene was detected by sequencing analysis in the proband JR2. This mutation cause the 301st amino acids codon swtch from CAA to TAA and the codogenic amino acids alterd from glutamine glutaminic acid to strong terminal codon. This mutation is also detected in all 11 patients of this family, but not present in the unaffected members in this family. Conclusion The premature translation termination of PAX6 gene caused by a nonsense mutation of Q310x should be responsible for congenital aniridia in this Chinese family.