Identification of ANXA2 as a Potential Susceptibility Gene for Diabetic Retinopathy in a Genome-Wide Association Analysis in Chinese Patients With Type 2 Diabetes Mellitus
Authors: Cheung Chloe Y Y , Lee Chi Ho , Fong Carol H Y , Chow Wing-Sun , Woo Yu Cho , Yuen Michele , Tan Kathryn C B , Xu Aimin , Sham Pak C , Lam Karen S L 
Published: May 2021

Abstract
Background: Diabetic retinopathy (DR) is the most frequent microvascular complication of type 2 diabetes mellitus (T2DM). Variation in allele frequencies between different ethnic groups may influence the detectability of the risk variants in different populations. It is therefore important to conduct ethnic-specific association analysis to discover novel loci. The major objective of this study was to conduct a 2-stage genome-wide association study (GWAS) to identify novel susceptibility single nucleotide polymorphisms (SNPs) for sight-threatening DR in Chinese patients with T2DM.
Methods and Materials: The discovery stage consisted of 681 STDR cases and 758 non-STDR controls of Southern Chinese ancestry. The Illumina Infinium Asian Screening Array (ASA) was used for genotyping of the subjects. Imputation was performed using the TOPMed Imputation Server. SNPs with minor allele frequency (MAF) &lt;0.01 and INFO score &lt;0.3 were excluded. Single variant association analysis was performed in SNPTEST using the multiple logistic regression model with adjustment for age, gender, duration of diabetes, hypertension, hemoglobin A1c (HbA1c), and the first five principal components. The replication cohort was comprised of an independent sample set of 278 STDR cases and 834 non-STDR controls. Meta-analysis of the association results of the discovery and replication stages was conducted using the “GWAMA” software. The inverse variance fixed-effect method was used to meta-analyze the summary statistics of the two stages.
Results: In the discovery stage, the strongest association was detected at an intronic variant of ANXA2 (P=1.87x10-7; OR[95%CI]:1.59[1.31–1.96]). Ninety-three SNPs showing suggestive associations (P&lt;5x10-5) with STDR in the discovery stage were selected for replication. In the meta-analysis of the two stages, the ANXA2 SNP again showed the strongest association with STDR (P=2.18x10-6; OR[95%CI]: 1.45[1.24–1.70]). ANXA2 encodes the annexin A2 which has been shown to play an important role in promoting angiogenesis. An intronic SNP of DOC2B, a tumor suppressor gene that exhibits functions in cell proliferation and migration, also demonstrated a marginal association with STDR (P=5.17x10-6; OR[95%CI]: 1.41[1.22–1.63]). Two intergenic variants located at the RPL31P11-FCRLA (P=7.25x10-6; OR[95%CI]: 1.54[1.27–1.85]) and COL6A1-COL6A2 (P=9.60x10-6; OR[95%CI]: 0.73[0.63–0.84]) loci also showed suggestive associations with STDR.
Conclusion: Several novel STDR-associated genetic variants were identified in this genome-wide association study. Our findings have shed new lights on the genetic basis of STDR in Chinese patients with T2DM. Further validation in independent cohorts to validate our findings are warranted.
Acknowledgements: This study was supported by the Research Grant Council – General Research Fund of Hong Kong (Ref no.: 17118119).