摘要目的:观察1例小口病患者的致病基因突变。方法:来自日本的1例小口病患者纳入研究，详细收集患者病史、家族史。行BCVA、OCT、眼底彩色照相、视野、全视野闪光ERG检查；采集患者外周静脉血，提取全基因组DNA。应用全外显子测序技术检测基因突变位点，应用分析软件明确该突变位点的保守性及可能引起的蛋白结构改变。结果:患者男，71岁。自幼夜盲；其父母为表兄妹近亲婚配。双眼BCVA均为0.7。眼底色泽呈灰暗、带有金黄色反光。双眼暗适应0.01反应熄灭，暗适应3.0反应a、b波振幅均明显降低，b波几乎消失，呈负波形。DNA测序发现SAG基因的一个纯合移码突变（c.924delA, p.N309Tfs*12 ）。该移码突变导致SAG编码蛋白的翻译提前终止，结构严重受损。蛋白序列同源性分析结果显示，该突变位点在多个物种中均高度保守，为有害性突变。结论:SAG基因突变位点c.924delA, p.N309Tfs*12是该患者的致病基因。

abstractsObjective:To identify the pathogenic mutation in a patient with Oguchi disease.Methods:A Japanese patient with Oguchi disease was enrolled in this study, and underwent a comprehensive medical history assessment and multiple ophthalmic examinations, including BCVA, OCT, color fundus photography and full field electroretinogram. Genomic deoxyribonucleic acid (DNA) was extracted from peripheral blood samples for whole exome sequencing. The gene mutation was detected, and the analysis software was used to determine the conservation of the mutation and the possible structural changes.Results:The patient, 71 years old, with consanguineous parents, complained of night blindness since early childhood. BCVA in both eyes was 0.7 and the golden-yellowish reflex appeared in the grey retina. The scotopic 0.01 ERGs showed a extinguished reaction in both eyes. The scotopic 3.0 ERGs showed a "negative" configuration with a significantly reduced a wave and a nearly absent b wave. A homozygous deletion mutation in the SAG gene (c.924delA, p.N309Tfs*12) in this patient was founded by DNA sequencing, which was predicted to generate prematurely truncated SAG protein and result in severe structural change. Homology analysis of the protein sequence indicated that the mutation resulted in an altered amino acid which was evolutionarily highly conserved among different species, strongly suggesting the potential pathogenicity of this homozygous mutation.Conclusion:The mutation c.924delA(309Tfs*12) in SAG cause Oguchi disease in this patient.