Corneal Dystrophy, Lisch Epithelial
Patient Information
Characteristics
Background and History
The cornea is the normally clear windshield of the eye. A number of gene mutations cause a clouding of this tissue so that vision is reduced. This is the only dystrophy (degeneration) of the cornea caused by a mutation in a gene on the X chromosome.
Clinical Correlations
This disorder may have its onset in childhood with the appearance of fuzzy, feathery deposits in a band or whorl pattern in the cornea. Tiny clear cysts can appear in the anterior surface. The corneal clouding is progressive and can lead to significant blurriness of vision. Unlike some forms of corneal dystrophy, there is seldom any irritation or discomfort from the disease. Contrary to expectations for an X-linked disorder, both males and females have corneal disease. No systemic abnormalities have been found.
Genetics
Inheritance
Lisch dystrophy is the result of a mutation on the X chromosome. In most X-linked disorders, males are primarily affected. They cannot pass on the disease to their sons since they only give their Y chromosomes to sons. However, in Lisch dystrophy the mutation is dominant so all their daughters (who must receive the mutant X chromosome) may have clinical evidence of disease in their corneas and they can pass the mutated X chromosome to both their sons and daughters. In such cases, your eye doctor can assist in determining the risk of transmission to children.
Pedigree
X-linked dominant, father affected
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or renders him unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or at least renders them unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked dominant, mother affected
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
Diagnosis and Prognosis
Since only the very superficial tissue of the eye is involved, treatment has been directed toward the removal of this tissue (it grows back in 24-48 hours). Unfortunately, the little cysts recur in the new layer as well. It has also been reported that contact lens wear reduces the opacities but they again tend to recur when wear is discontinued. Treatment is seldom needed however as most patients retain near normal vision throughout life.
Web Resources
Printer Friendly Version: Ctrl/Cmd+P