FZD4基因与家族性渗出性玻璃体视网膜病变关系的研究

Novel frizzled-4 gene mutations in Chinese patients with familial exudative vitreoretinopathy

目的研究家族性渗出性玻璃体视网膜病变(familial exudative vitreoretinopathy,FEVR)患者卷曲蛋白4基因(Frizzled 4,FZD4)突变类型和频率,探讨其基因型-表型之间的关系。设计实验研究。研究对象2004年11月至2012年3月北京大学人民医院及北京同仁医院FEVR患者51例,其中家系病例39例,散发病例12例;同期北京大学人民医院体检100例正常对照个体。方法应用聚合酶链反应(PCR)扩增全基因组DNA,用直接测序法检测FZD4所有外显子及邻近的非编码区序列。FZD4基因突变用生物信息法分析突变可能引起的蛋白结构和功能性改变。主要指标基因序列。结果在FZD4基因所有2个外显子及邻近的非编码区共检出12个致病性突变,其中9个为新发现的突变:1个缺失突变(P14fsX57)、1个无义突变(S491X)、7个错义突变(G22E、E180K、T237R、R253C、F328S、A339T、D470N)。3个已报道的致病突变:H69Y、M105V和W496X。在2个家系中同时发现携带2个不同的FZD4基因突变(分别为:H69Y和E180K;H69Y和W496X),且这些患者临床表型严重于携带1个突变的患者。FZD4基因在FEVR患者中的突变率为29.4%(15/51);且均为常染色体显性遗传。结论 FZD4基因突变与中国人FEVR发病有关,其突变率约30%。突变率和其他人种相似,但突变谱具有明显的特异性。

Objective To investigate the genotype and phenotypic features of FZD4 mutations in Chinese familial exudative vit- roretinopathy （FEVR） patients. Design Experimental study. Participants Fifty-one Chinese patients with FEVR and 100 unrelated con- trol subjects were recruited and complete ophthalmic examinations performed. Method The coding regions of FZD4 gene was screened for mutations by polymerase chain reaction and direct sequencing. Multiple sequence alignment was conducted to evaluate the conser- vancy of residues among different FZD4 homologs and human frizzled family. Genotype-phenotype correlations were also analyzed. Main Outcome Measures Gene sequences. Results Totally twelve putative disease-causing mutations were identified, nine of them novel： one deletion （P14fsX57）, one nonsense mutations （S491X） and seven missense mutations （G22E, E180K, T237R, R253C, F328S, A339T and D470N）. Three reported FZD4 mutations were also detected： H69Y, M105V and W496X. Remarkably, two patients, who harbored compound heterozygous mutations （H69Y with E180K or W496X）, had a more severe ocular phenotype than carriers of single H69Y mutation. Conclusion FZD4 mutations were responsible for 29.4% （15/51） of Chinese FEVR patients in this study, similar to other eth- nic groups. This study supported the highly polymorphic nature of FZD4 with a differential mutation profile in the Chinese population. The profile of the mutations obtained in FZD4 gene further illustrated the complexity of FEVR and provided a better understanding on the genotype phenotype correlations. （Ophtholmol CHN, 2013, 22： 224-229）