我国常染色体显性遗传视网膜色素变性家系中PRPF31基因新的剪切位点突变

目的　研究我国一个4代常染色体显性遗传视网膜色素变性(RP)家系患者的致病基因突变位点及临床表型特征。方法　对RP家系中的所有患者进行眼部及视觉电生理检查;对全部家系成员进行全基因组扫描及连锁分析, 对候选基因直接测序并通过限制性内切酶反应证实突变位点。结果　RP家系患者致病基因定位于染色体带19q13 4,微卫星标记物D19S589和D19S254之间不到4Mb区域。在所有患者的PRPF31基因内含子8的第一个碱基处发现一新的杂合突变(G>C),使内含子8的剪切供体由GT变为CT。RP家系患者的临床表型符合早期发病且弥漫型的RP患者类型。结论　我国该4代RP家系中的患者由PRPF31基因中一新的剪切位点的杂合突变致病(IVS8+1G>C)。

Novel splice-site mutation in the pre-mRNA splicing gene PRPF31 in a Chinese family with autosomal dominant retinitis pigmentosa

Objective To identify mutations in a four-generation Chinese family with retinitis pigmentosa and to investigate its clinical phenotype. Methods Ophthalmic and electrophysiological examinations of patients with RP were performed. A genome-wide scan and linkage analysis were conducted in this family. Direct genomic sequencing was used to evaluate the candidate gene. A restriction assay was used to confirm the mutation status in this family, and to exclude it as a polymorphism in a reference population. Results The mutation gene was mapped close to RP11 in chromosomal region 19q13.4 by linkage analysis. A novel single heterozygous base substitution (G>C) was detected at the beginning of intron 8 in the PRPF31 gene whereby the consensus GT dinucleotide of the intron 8 splice donor site was changed to CT. The mutation was co-segregated completely with the disease phenotype, but was absent in the unaffected relatives and in 100 reference subjects, thus supporting its pathogenic nature in this family. The clinical findings of RP patients were consistent with a relatively severe and diffuse type of RP. Conclusion A novel splice site mutation (IVS8+1G>C) in the PRPF31 gene caused retinitis pigmentosa in the four-generation Chinese RP family studied.