一个视网膜色素变性家系的视紫红质基因突变分析

A recurrent rhodopsin gene missense mutation in a Chinese family with autosomal dominant retinitis pigmentosa

目的 确定常染色体显性遗传视网膜色素变性家系的致病基因及其突变位点,并研究其临床表型。方法 对一个常染色体显性遗传视网膜色素变性(autosomal dominat retinitis pigmentosa,ADRP)家系成员进行了视力、视野及眼底镜检查,并对该家系中先证者进行了视网膜电流图分析。应用聚合酶链反应和直接测序技术,对该家系的所有现存人员的视紫红质基因的外显子进行测序分析。结果 该家系的2 5名成员中12例患者有视紫红质基因(rhodopsin,RH O)的5 12 C>T(P171L)突变,均呈杂合子,该错义突变使密码子171由CCA变成CTA。而未受累者的视紫红质基因表现为野生型。该家系患者的临床表现为5～6岁时出现夜盲,在2 0～30岁逐渐出现视力和视野损害,并先后在4 0～5 0岁前后失明,其中2例患者并发青光眼,先证者的闪烁视网膜电图呈熄灭型。结论 视紫红质基因RH O的一种已知突变5 12 C>T(P171L)是该家系的病因。与国外相同的基因突变类型相比较,该家系发病早、病情进展快、视功能损害较重。

Objective To detect mutation in the rhodopsin gene ( RHO ) in a Chinese family with autosomal dominant retinitis pigmentosa (ADRP). Methods A total of 25 family members from a Chinese family were investigated. All the subjects were examined clinically by direct funduscopy, perimetry and vision test. Evaluation of the proband included electroretinography (ERG). Genomic DNA was extracted using standard method. The complete coding regions of RHO were amplified by polymerase chain reaction (PCR) and the PCR products were subjected to automatic DNA sequencing. Results 512 C>T (P171L), a recurrent missense mutation was detected in the proband. All 12 affected subjects in the family were heterozygous for the mutation. The affected individuals had night blindness at the age of 5-6 years. They had relatively severe impairment of visual acuity and suffered a gradual loss of peripheral visual field at the age of 20-30 years. And they went blind at the age of 40-50 years. Rod and cone ERG were not detectable in the proband. Conclusion A recurrent missense mutation, 512C>T (P171L), was detected in a Chinese family with ADRP.