Fish-eye disease

What causes fish-eye disease?

Fish-eye disease is caused by changes (mutations) in the LCAT gene. This gene encodes an enzyme that helps remove cholesterol from the blood and certain tissues. It carries out this role by helping cholesterol attach to lipoproteins, which carry it to the liver for redistribution to certain tissues or for removal. Fish-eye disease occurs when mutations impair the enzyme's ability to attach cholesterol to a lipoprotein called high-density lipoprotein (HDL), specifically. As a result, cholesterol begins to cloud the cornea. It is unclear why cholesterol deposits almost exclusively affect the cornea in this condition.

Of note, mutations that affect the enzyme's ability to attach cholesterol to HDL, low-density lipoprotein, and very low-density lipoprotein lead to a related disorder called complete LCAT deficiency, which involves corneal opacities in combination with features affecting other parts of the body.

Last updated on 05-01-20

How is fish-eye disease diagnosed?

A diagnosis of fish-eye disease is first suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to confirm the diagnosis and rule out other conditions that can be associated with similar features. This testing may include:

  • Genetic testing to identify two mutations in the LCAT gene.
  • Testing that analyzes the function of the enzyme encoded by the LCAT gene.
  • Specialized urine and blood tests.

Last updated on 05-01-20

Is fish-eye disease inherited?

Fish-eye disease is inherited in an autosomal recessive manner. This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:

  • 25% (1 in 4) chance to be affected
  • 50% (1 in 2) chance to be an unaffected carrier like each parent
  • 25% chance to be unaffected and not be a carrier

Last updated on 05-01-20

How might fish-eye disease be treated?

Treatments are available to help manage the signs and symptoms of fish-eye disease. Affected people will generally be followed by an ophthalmologist to monitor and treat worsening visual impairment. In severe cases, corneal transplantation may be recommended. Researchers are currently studying other potential therapies. For example, one recent study suggested that statins (cholesterol-reducing medications) could be prescribed in people affected by fish-eye disease to reduce the risk of atherosclerosis.

Last updated on 05-01-20


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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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