ABCA1 and Tangier disease: Genetic mutations in ABCA1 (Tangier disease), LCAT (familial lecithin:cholesterol acyltransferase deficiency), ApoA1 (familial apolipoprotein (Apo) A1 deficiency), and UBIAD1 (Schnyder corneal dystrophy, SCD) all result in corneal accumulation of lipids including cholesterol.