Norrie Disease
Patient Information
Characteristics
Background and History
This disease was first described by Gordon Norrie, a Danish ophthalmologist who described the features in 1927.
Clinical Correlations
This disorder presents at birth or soon thereafter, when a white reflex is seen in the pupil (leukocoria). There may be no response to light even at this early stage. The eyeballs are often small as well and cataracts often develop. The iris (colored part of the eye) may be abnormal. The pupillary reflex represents reflections from an enlarging mass in the back of the eye due to abnormal development of the retina. Hemorrhage from this mass often leads to a retinal detachment. The condition may be unilateral but typically involves both eyes with some asymmetry. Most patients become deaf by the second decade of life. Many have some mental deficiency with growth delays as well. Some patients have seizures and occasional adults have behavioral problems or frank psychoses.
Genetics
Inheritance
This is an X-linked disorder in which only males are affected. Many are unable to reproduce. Carrier females are not affected but can pass the mutant X-chromosome to each of their sons with a 50% chance and half of their daughters will be carriers like themselves.
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.
Diagnosis and Prognosis
The diagnosis is usually made by an ophthalmologist in cooperation with neurologists and pediatricians. Life expectancy is usually not shortened but the blindness and deafness create challenges for caregivers.
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