Fish eye disease is a rare, autosomal recessive inherited disorder of the lipid metabolism, which is caused by a partial defect of the liver enzyme lecithin-cholesterol acyltransferase (LCAT). A severe reduction of plasma HDL-cholesterol (< 10 mg/dl, hypoalphalipoproteinemia) with a concomitant reduction in the proportion of cholesteryl esters, which is attributable to a defect in maturation of the HDL particles, is a characteristic feature of fish eye disease. LCAT plays a vital role in the maturation of HDL particles as it provides cholesteryl esters as a core component to lipoproteins. LCATs main site of action are immature apoA-I containing HDL particles.
Fish eye disease is characterized clinically by corneal opacification, which makes the eyes of affected individuals resemble those of boiled fish. A complete loss of function of the LCAT enzyme is referred to as classic LCAT deficiency and, besides reduced HDL concentration and corneal opacity, is associated with a modest hypertriglyceridemia as well as glomerulosclerosis. The latter may progress to end-stage renal failure requiring kidney transplantation. A increased risk for coronary heart disease is described for homozygous carriers of LCAT deficiency but not for fish eye disease.