Congenital stromal corneal dystrophy

Description

Congenital stromal corneal dystrophy is an inherited eye disorder that primarily affects the clear layer that covers the front surface of the eye (cornea). Affected individuals have multiple corneal opacities, which are damaged areas that cause the cornea to appear cloudy or opaque rather than transparent. These corneal opacities form in the thickest layer of the cornea (stroma) and are typically present in both eyes (bilateral) from birth or soon thereafter. The corneas of affected individuals may also be thicker than normal and have an irregular surface. These corneal changes lead to a loss of visual acuity, which can impair a person’s ability to see clearly. Without treatment, visual acuity can worsen over time.

Congenital stromal corneal dystrophy is often associated with additional eye abnormalities, including eyes that do not look in the same direction (strabismus) and "lazy eye" (amblyopia). Less commonly, affected individuals may have involuntary eye movements (nystagmus) or increased sensitivity to light (photophobia).

Frequency

Congenital stromal corneal dystrophy is rare; only a few affected families have been reported in the medical literature.

Causes

Congenital stromal corneal dystrophy is caused by variants (also called mutations) in the DCN gene. This gene provides instructions for making a protein called decorin, which is involved in the organization of collagens. Collagens are proteins that strengthen and support connective tissues such as skin, bone, tendons, and ligaments. Collagens also play an important role in the cornea. Bundles of collagen called fibrils must be strictly organized for the cornea to be transparent. Decorin helps ensure that these collagen fibrils are the right size and are regularly spaced.

The variants in the DCN gene that cause congenital stromal corneal dystrophy lead to the production of an abnormal version of decorin that does not function as it should. Researchers believe that this abnormal protein accumulates in the cornea, which causes the cornea to become cloudy. The accumulation of abnormal decorin may also lead to the other eye abnormalities seen in people with congenital stromal corneal dystrophy.

Inheritance

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Some cases of this condition likely result from new (de novo) variants in the gene that occur during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These affected individuals typically have no history of the disorder in their family.

Autosomal dominant inheritance with a new (de novo) mutation. Credit: U.S. National Library of Medicine.

Other Names for This Condition

• Congenital hereditary stromal dystrophy of the cornea
• Congenital stromal dystrophy of the cornea
• CSCD
• Decorin-associated congenital stromal corneal dystrophy
• Dystrophia corneae parenchymatosa congenita
• Witschel dystrophy

Where this page came from

This page was imported from MedlinePlus Genetics, National Library of Medicine. Courtesy of MedlinePlus from the National Library of Medicine; its genetics summaries and the illustrations credited to the library are in the public domain. Pictures credited to others are not copied.

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