COL4A4 and keratoconus: We also discovered through analysis of both models that some of the genotypes were significantly less frequent in KC patients: 976TT and 2685AA in COL4A3 and 1444CC and 4932 TT in COL4A4 for the dominant model; 422TT and 976TT in COL4A3 and 3979AA, 4548GG, and 4932TT in COL4A4 for the recessive model (Table 5).