OMIM ID:
Corneal Dystrophy, Endothelial X-Linked
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Corneal opacification is severe in males and has been described as resembling ground glass, or having a milky white appearance throughout the entire cornea. Corneal clouding may be seen in infants but progresses with age in most cases. In a 7 generation Austrian family, nine males had severe corneal opacification, seven with band keratopathy and 2 with the typical ground glass appearance. Vision may be 20/20 even in adults but the majority have acuities in the range of 20/30 to 20/60 even into the 7th decade. A few have vision of 20/100 to 20/400 even as young adults and one 19 year old was reported with nystagmus. The corneas of twenty-two females and four males were said to have only a ‘moon crater-like’ appearance resulting from focal discontinuities in the endothelial layer. Tissue studies of a keratoplasty button from a 60 year old male revealed endothelial degeneration and thickening of the Descemet membrane. There may also be irregular thinning of the epithelial and Bowman layers.
Systemic Features
No systemic disease associations have been reported.
Genetics
Inheritance
This is the only endothelial dystrophy that is X-linked (Xq25). A single family has been reported and the molecular mutation is unknown. Females may be affected but less severely than males and are usually asymptomatic. In a large pedigree in which 60 individuals were studied, no male-to-male transmission was found.
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.
X-linked recessive, carrier mother
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the mother, she usually does not have the disease since the normal X chromosome without the mutation neutralizes the mutation in the abnormal X chromosome. However, half her sons will inherit the mutation-containing X chromosome and therefore have the X-linked disease. Half the daughters will inherit the mutation-bearing X chromosome and are usuallly healthy 'carriers'.
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the mother, she usually does not have the disease since the normal X chromosome without the mutation neutralizes the mutation in the abnormal X chromosome. However, half her sons will inherit the mutation-containing X chromosome and therefore have the X-linked disease. Half the daughters will inherit the mutation-bearing X chromosome and are usuallly healthy 'carriers'.
X-linked recessive, father affected
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the father, he has the disease since his only X chromosome is mutant and he has no normal X to blunt the effects of the abnormal gene. His sons only receive his Y chromosome and thus are all normal. However, all his daughters receive his one and only X chromosome and will be healthy 'carriers'. Thus such males will have no affected children but half their grandsons from those daughters will have the same disease as he does.
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the father, he has the disease since his only X chromosome is mutant and he has no normal X to blunt the effects of the abnormal gene. His sons only receive his Y chromosome and thus are all normal. However, all his daughters receive his one and only X chromosome and will be healthy 'carriers'. Thus such males will have no affected children but half their grandsons from those daughters will have the same disease as he does.