我国诺里病家系NDP基因的突变分析

Analysis of gene mutation in a Chinese family with Norrie disease

目的对我国诺里病一家系进行致病基因突变的鉴定，确定其家系中是否存在ⅣDP基因突变。方法基因家系研究。发现一个3代均患有诺里病的家系，共13人，患者3人，现存患者仅先证者1人，为20月龄男孩。根据诺里病家族史、临床体征及眼科B超检查对患者进行临床诊断；采集该家系成员外周血标本，常规提取基因组DNA；设计并合成3对特异性引物，通过PCR扩增NDP基因的外显子及外显子与内含子交界区，PCR产物直接测序；通过PCR产物限制性内切酶分析和基因型分析对家系所有13名成员进行突变鉴定。结果基因测序结果显示先证者及其母亲均具有NDP基因突变C．220C〉T（P．Arg74Cys），且先证者为该突变的半合子，其母为该突变的携带者；NDP基因突变鉴定表明家系中另外4个表型正常的个体（Ⅲ3、Ⅳ4、Ⅲ5和Ⅱ2）均为该突变的携带者。结论我国诺里病一家系中发现存在NDP错义突变C．220C〉T。

Objective To detect the pathogenic mutation in a Chinese family with Norrie disease. Methods Clinical diagnosis was based on familial history, clinical sign and B ultrasonic examination. Peripheral blood samples were obtained from all available members in a Chinese family with Norrie disease. Genomie DNA was extracted from lymphoeytes by the standard SDS-proteinase K-phenol/chloroform method. Two coding exons and all intron-exon boundaries of the NDP gene were PCR amplified using three pairs of primers and subjected to automatic DNA sequence. The causative mutation was confirmed by restriction enzyme analysis and genotyping analysis in all members. Results Sequence analysis of NDP gene revealed a missense mutation c. 220C 〉 T （p. Arg74Cys ） in the proband and his mother. Further mutation identification by restriction enzyme analysis and genotyping analysis showed that the proband was homozygote of this mutation. His mother and other four unaffected members （Ⅲ3、Ⅳ4、Ⅲ5 and Ⅱ2） were carriers of this mutation. The mutant amino acid located in the C-terminal cystine knot-like domain, which was critical motif for the structure and function of NDP. Conclusion A NDP missense mutation was identified in a Chinese family with Norrie disease.