Microphthalmia, Syndromic 4
Patient Information
Characteristics
Background and History
Microphthalmia (small eyes) may be so severe that no eye tissue is visible (clinical anophthalmia) as in this disorder.
Clinical Correlations
A single family with this condition has been reported in 7 males in 2 generations. The eyelids were fused together and X-rays revealed the bony orbits to be underdeveloped, consistent with the lack of eye tissue. No vision is present. All affected males were mentally retarded as well. One individual also had a partial cleft palate.
Genetics
Inheritance
No responsible gene mutation has been found but a region (locus) on the X-chromosome likely to contain the gene has been identified. The pedigree and the pattern of transmission are consistent with X-linked inheritance. Thus, only males have this condition and would not have affected children. Women who carry the mutation are clinically normal but can expect that half of their male offspring will have microphthalmia. In view of the clinical severity (mental retardation) it is unlikely that affected males will have offspring.
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'.
Diagnosis and Prognosis
Pediatricians and ophthalmologists are likely to collaborate in the diagnosis and care of affected children. No treatment is available for this disorder and nothing is known regarding longevity.
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