OMIM ID:
Myopia 1, X-linked, Nonsyndromal
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Nonsyndromal high myopia of -6D to -23D has been reported in multigenerational families. No other ocular abnormalities have been found. Detection is usually late in the first decade of life.
Systemic Features
No systemic disease has been reported.
Genetics
Inheritance
Only males were reported to be highly myopic in two large multigenerational Indian families. The transmission pattern was consistent with an X-linked recessive mode of inheritance. Only males were affected and no male-to-male transmission was observed. In another nonAsian family, 3 brothers with myopia had 5 myopic grandsons, all offspring of their daughters. The daughters had low grade myopia not requiring correction.
The presumed locus for MYP1 is located at Xq28, in the same location as the presumed gene for Bornholm Eye Disease (300843) in which high myopia is also found.
Pedigree
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.