Revisiting the Trans-Ancestry Genetic Correlation of Refractive Error.

Purpose: The prevalence of myopia varies significantly across the globe. This may be a consequence of differences in exposure to lifestyle risk factors or differences in genetic susceptibility across ancestry groups. "Trans-ancestry genetic correlation" quantifies the similarity in genetic predisposition to a trait or disease between different populations. We estimated the trans-ancestry genetic correlation of refractive error across Europeans, South Asians, East Asians, and Africans using recently developed approaches.

Methods: Two methods were applied: (1) trans-ancestry genetic correlation with unbalanced data resources (TAGC-UDR) and (2) trans-ancestry bivariate genomic-relatedness-based restricted maximum-likelihood (TAB-GREML). TAGC-UDR analyses were carried out for UK Biobank participants of European (n = 3500), East Asian (n = 972), South Asian (n = 4303), and African (n = 3877) ancestry. TAB-GREML analyses were carried out for participants of European (n = 10,000), South Asian (n = 4303), and African (n = 3877) ancestry.

Results: TAGC-UDR analyses suggested the trans-ancestry genetic correlation of refractive error was in the range 0.7-1.0 for the European versus African, European versus East Asian, and European versus South Asian ancestry pairs. The TAB-GREML estimates were consistent with the TAGC-UDR findings. Precision of the estimates was limited, reflecting the modest sample sizes of the non-European samples.

Conclusions: These results support and extend previous work suggesting that genetic susceptibility to refractive error is largely shared across Europeans, Africans, and South Asians. This suggests geographical differences in myopia prevalence are mostly driven by lifestyle factors or rare genetic variants not considered in the current work.