To date, VSX1 is recognized as a possible but not definitive KC gene—some mutations in VSX1 may cause atypical corneal dystrophies (like posterior polymorphous corneal dystrophy) that can co-occur with keratoconus, but the majority of sporadic KC cases do not seem to be explained by VSX1 mutations [25,26,27]. The gene discussed is VSX1; the disease is posterior polymorphous corneal dystrophy.