The following four variants were identified in the four probands and other family members with KC: heterozygous missense variation c.109G>A (p.Glu37Lys, rs369263247) in the procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (<i>PLOD1</i>) gene; heterozygous missense variation c.3766G>A (p.Ala1256Thr, rs148216434) in the collagen type I alpha 1 (<i>COL1A1</i>) gene; heterozygous missense variant c.4364G>A (p.Gly1455Glu) in the collagen type V alpha 2 (<i>COL5A2</i>) gene; and missense variation c.976G>A (p.Glu326Ser) in the collagen type IV alpha 1 (<i>COL4A1</i>) gene. The gene discussed is COL4A1; the disease is keratoconus.