Fish-eye disease

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Reviewed August 2013

What is fish-eye disease?

Fish-eye disease, also called partial LCAT deficiency, is a disorder that causes the clear front surface of the eyes (the corneas) to gradually become cloudy. The cloudiness, which generally first appears in adolescence or early adulthood, consists of small grayish dots of cholesterol (opacities) distributed across the corneas. Cholesterol is a waxy, fat-like substance that is produced in the body and obtained from foods that come from animals; it aids in many functions of the body but can become harmful in excessive amounts. As fish-eye disease progresses, the corneal cloudiness worsens and can lead to severely impaired vision.

How common is fish-eye disease?

Fish-eye disease is a rare disorder. Approximately 30 cases have been reported in the medical literature.

What genes are related to fish-eye disease?

Fish-eye disease is caused by mutations in the LCAT gene. This gene provides instructions for making an enzyme called lecithin-cholesterol acyltransferase (LCAT).
The LCAT enzyme plays a role in removing cholesterol from the blood and tissues by helping it attach to molecules called lipoproteins, which carry it to the liver. Once in the liver, the cholesterol is redistributed to other tissues or removed from the body. The enzyme has two major functions, called alpha- and beta-LCAT activity. Alpha-LCAT activity helps attach cholesterol to a lipoprotein called high-density lipoprotein (HDL). Beta-LCAT activity helps attach cholesterol to other lipoproteins called very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL).
LCAT gene mutations that cause fish-eye disease impair alpha-LCAT activity, reducing the enzyme's ability to attach cholesterol to HDL. Impairment of this mechanism for reducing cholesterol in the body leads to cholesterol-containing opacities in the corneas. It is not known why the cholesterol deposits affect only the corneas in this disorder. Mutations that affect both alpha-LCAT activity and beta-LCAT activity lead to a related disorder called complete LCAT deficiency, which involves corneal opacities in combination with features affecting other parts of the body.
Read more about the LCAT gene.
Read more about complete LCAT deficiency.

How do people inherit fish-eye disease?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Where can I find information about diagnosis or management of fish-eye disease?

These resources address the diagnosis or management of fish-eye disease and may include treatment providers.

You might also find information on the diagnosis or management of fish-eye disease in Educational resources and Patient support.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.

Where can I find additional information about fish-eye disease?

You may find the following resources about fish-eye disease helpful. These materials are written for the general public.

MedlinePlus - Health information (2 links)
Additional NIH Resources - National Institutes of Health
National Eye Institute: Facts About the Cornea and Corneal Disease
Educational resources - Information pages (3 links)
Patient support - For patients and families (3 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

Genetic Testing Registry - Repository of genetic test information (1 link)
ClinicalTrials.gov - Linking patients to medical research
PubMed - Recent literature
OMIM - Genetic disorder catalog

What other names do people use for fish-eye disease?

alpha-LCAT deficiency
alpha-lecithin:cholesterol acyltransferase deficiency
dyslipoproteinemic corneal dystrophy
FED
LCATA deficiency
partial LCAT deficiency

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines and How are genetic conditions and genes named? in the Handbook.

What if I still have specific questions about fish-eye disease?

Ask the Genetic and Rare Diseases Information Center

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding fish-eye disease?

autosomal ; autosomal recessive ; cell ; cholesterol ; deficiency ; enzyme ; gene ; HDL ; LDL ; lipoprotein ; recessive ; VLDL
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.

References (6 links)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.