For the first time we found an SNP in the cytotoxic lymphocyte-associated antigen-4 (CTLA4) gene associated with KC risk (2q33.2, rs231779 OR = 0.94; 95% CI = 0.92–0.95, P-value = 9.7 × 10−15; Supplementary Material, Table S2). Here, CTLA4 is linked to keratoconus.