GRB2 and type 2 diabetes mellitus: In this scenario, a genome-wide association study (GWAS) conducted by Burdon et al. [10] identified novel risk loci for sight-threatening DR (defined as severe NPDR, PDR, or macular edema) in white Australians with type 2 DM (T2DM), including a genetic variant located 17 kb upstream of the growth factor receptor-bound protein 2 (GRB2) gene on chromosome 17q25.1 (rs9896052; A>C).