Rare Ophthalmology News

Disease Profile

Macular dystrophy, corneal type 1

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

All ages

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ICD-10

H18.5

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

MCDC1; Corneal dystrophy, macular type; Groenouw type II corneal dystrophy;

Categories

Congenital and Genetic Diseases; Eye diseases

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 98969

Definition
Macular corneal dystrophy (MCD) is a rare, severe form of stromal corneal dystrophy (see this term) characterized by bilateral ill-defined cloudy regions within a hazy stroma, and eventually severe visual impairment.

Epidemiology
Prevalence of this form of corneal dystrophy is not known. Cases of MCD have been identified worldwide. The condition is most prevalent in India, Saudi Arabia, Iceland and parts of the USA.

Clinical description
Whitish opacities in the cornea usually appear during adolescence but may develop in early infancy, or as late as the 6th decade of life. The non-transparent areas progressively merge as the entire corneal stroma becomes cloudy, causing severe visual impairment usually before the 5th decade. The bilateral corneal opacities progressively extend through the entire thickness of the central and peripheral corneal stroma. The corneal stroma is thinner than normal.

Etiology
Most cases of MCD are caused by mutations in the CHST6 gene (16q22) encoding a protein involved in the production of keratan sulfate, which plays a role in the maintenance of corneal transparency. More than 125 mutations in this gene have been identified to date.

Diagnostic methods
MCD is characterized histopathologically by intracytoplasmic accumulations of non-sulfated keratan sulfate within the keratocytes and corneal endothelium, sparing the corneal epithelium. MCD is classified as a corneal stromal dystrophy but also involves the Descemet membrane and the corneal endothelium.

Differential diagnosis
The clinical features of MCD are similar to the corneal involvement found in the systemic mucopolysaccharidoses, such as mucopolysaccharidosis type IH and IS and the mucolipidoses (see these terms).

Genetic counseling
An autosomal recessive mode of inheritance has been shown in most cases, but some cases are of unknown etiology.

Management and treatment
Since the condition affects the entire corneal stroma, Descemet membrane and corneal endothelium, lamellar keratoplasty does not excise all damaged tissue. Corneal transplantation may therefore be needed. Vision can be restored by corneal grafting but opacities may recur in the graft after many years.

Visit the Orphanet disease page for more resources.

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of metabolism/homeostasis
Laboratory abnormality
Metabolism abnormality

[ more ]

0001939
Corneal crystals
0000531
Punctate opacification of the cornea
0007856
30%-79% of people have these symptoms
Decreased corneal thickness
Thin cornea
0100689
Recurrent corneal erosions
Recurrent breakdown of clear protective layer of eye
0000495
Severely reduced visual acuity
Marked vision impairment
Severe visual impairment
Severely impaired vision

[ more ]

0001141
5%-29% of people have these symptoms
Decreased corneal sensation
0012155
Hyperopic astigmatism
0000484
Ocular pain
Eye pain
0200026
Photophobia
Extreme sensitivity of the eyes to light
Light hypersensitivity

[ more ]

0000613
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
0000007
Corneal dystrophy
0001131
Juvenile onset
Signs and symptoms begin before 15 years of age
0003621
Macular dystrophy
0007754

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Macular dystrophy, corneal type 1. Click on the link to view a sample search on this topic.