VSX1 and keratoconus: Over the years, many studies have postulated multiple chromosomal regions and genes (e.g., 5q31, 15q22.32-24.2, VSX1, TGFBI, ZEB1, MIR184, SOD1, and ZNF469) to be causative; therefore, KC is suspected to be a genetically heterogeneous disease (Rabinowitz, 2003; Valgaeren et al., 2018).