Moreover, 2 SNPs in the COL4A4 gene identified by candidate gene studies were strongly associated with keratoconus in Whites, namely rs2229813 (P = 1.3 × 10−12, odds ratio (OR) = 2.38; I2 = 0) and rs2228557 (P = 4.5 × 10−7, OR = 0.54; I2 = 0) (Supplementary Table 2 and Fig. 2). Here, COL4A4 is linked to keratoconus.