Nine loci for ocular axial length identified through genome-wide association studies, including shared loci with refractive error

Refractive errors are common eye disorders of public health importance worldwide. Ocular axial length (AL) is the major determinant of refraction and thus of myopia and hyperopia. We conducted a meta-analysis of genome-wide association studies for AL, combining 12,531 Europeans and 8,216 Asians. We identified eight genome-wide significant loci for AL (<i>RSPO1</i>, <i>C3orf26</i>, <i>LAMA2</i>, <i>GJD2</i>, <i>ZNRF3</i>, <i>CD55</i>, <i>MIP</i>, and <i>ALPPL2</i>) and confirmed one previously reported AL locus (<i>ZC3H11B</i>). Of the nine loci, five (<i>LAMA2</i>, <i>GJD2</i>, <i>CD55</i>, <i>ALPPL2</i>, and <i>ZC3H11B</i>) were associated with refraction in 18 independent cohorts (n = 23,591). Differential gene expression was observed for these loci in minus-lens-induced myopia mouse experiments and human ocular tissues. Two of the AL genes, <i>RSPO1</i> and <i>ZNRF3</i>, are involved in Wnt signaling, a pathway playing a major role in the regulation of eyeball size. This study provides evidence of shared genes between AL and refraction, but importantly also suggests that these traits may have unique pathways.