中国人群糖尿病视网膜病变易感基因TBC1D4、COMMD6和UCHL3的精细作图研究

Diabetic retinopathy (DR) is one of the leading causes of blindness in Chinese working-age adults. Identified by the previous DR genome-wide association study (GWAS) in Chinese, TBC1D4, COMMD6 and UCHL3 genes might affect the occurrence and development of DR by influencing apoptosis, inflammation, etc. However, it is still unknown regarding to their causal variations for DR. There is a lack of large scale screening for genetic variations and their functions in the three genes. Therefore, based on the existing results of GWAS, we plan to fine-map the exons of three genes (TBC1D4, COMMD6 and UCHL3) in 200 extreme DR cases and 200 controls through target capture and sequencing, then verify the causal variations in a large population, and finally investigate the potential functions of these variations through molecular biology methods. The study results may be used to screen high-risk population and provide a new tool for early prevention, diagnosis and treatment of DR.

糖尿病视网膜病变（diabetic retinopathy，DR）是我国工作人群致盲的主要原因之一。TBC1D4、COMMD6和UCHL3基因是中国人群全基因组关联研究（GWAS）发现的DR易感基因，可能通过影响细胞凋亡、炎症反应等通路从而影响DR的发生和发展。然而，目前这三个基因真正的致病位点仍不清楚，国内尚缺乏针对该易感区域突变位点及其功能的大规模筛选研究。因此，本课题拟在已有GWAS研究成果基础上，针对TBC1D4、COMMD6和UCHL3三个基因的外显子区，运用目标区域捕获测序技术在200对极端DR病例-对照中进行精细作图，进而在大样本人群中验证致病位点，最后通过分子生物学手段解析遗传变异对DR发生的作用机制。研究成果有望用于DR高危人群筛查，为实施个体化预防和早诊早治提供理论和技术支持。

全基因组关联研究（genome-wide association study，GWAS）已发现了多个中国人群糖尿病视网膜病变（diabetic retinopathy，DR）易感区域。然而，这些易感区域内的致病基因和真正致病位点尚不清楚。本研究旨在通过对中国人群DR易感基因进行精细作图来鉴定DR相关变异。本研究在101例DR患者和103例对照中对中国人群DR易感基因TBC1D4、COMMD6、UCHL3、LRP2、BBS5、ARL4C和SH3BP4外显子区进行捕获测序。通过Logistic回归和计数法评估常见、罕见变异与DR发生之间的关联。对于鉴定的DR相关变异，采用功能注释来评估其潜在的生物学功能。研究发现LRP2基因上4个常见变异与DR风险相关（P<0.05）。此外，鉴定了12个DR相关功能性罕见变异，其CADD评分均大于20：LRP2 rs764804647、LRP2 rs538396567、LRP2 Chr2:170010984、LRP2 Chr2:170050282、LRP2 Chr2:170129538、LRP2 Chr2:170129539、LRP2 rs754796717、LRP2 rs529409328、UCHL3 Chr13:76135016、TBC1D4 Chr13:75876471、TBC1D4 rs201459702、SH3BP4 Chr2:235950303。对12个DR相关功能性罕见变异在1000对DR病例-对照中进行大样本独立人群验证，通过Logistic回归分析鉴定了3个DR相关遗传变异，进一步功能学实验证实LRP2 Chr2:170129538 T>C影响LRP2蛋白表达。研究成果可为中国人群DR遗传模型的构建提供依据，将来有望用于临床上DR高危人群的筛查及个体化预防和早诊早治的实施。