Ataxia with Oculomotor Apraxia 4
Patient Information
Characteristics
Background and History
Hereditable neurologic conditions are often associated with ataxia consisting of difficulties with balance and unsteadiness. Other symptoms are almost always present depending upon which brain structures are involved in the disease. In this disorder, patients have difficulty initiating movements of their eyes in addition to having other neurologic deficits.
Clinical Correlations
The first symptoms consisting of dystonia (purposeless movements of the limbs) appear at a mean age of 4.3 years of age. Difficulty with balance often appears next followed by the difficulty in eye movements. Most individuals have some cognitive impairment early which may sometimes lead to severe dementia. Muscle weakness and wasting is progressive and patients may become confined to a wheelchair by the second to third decade of life. Patients may have diminished reflexes and sensation. Vision is normal.
Genetics
Inheritance
This is an autosomal recessive disorder resulting from mutations in both copies of a specific gene. Parents who are clinically normal are each a carrier of one mutation and have a 25% risk of both contributing the changed genes to each child.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
Infants and very young children seem normal in the first years of life until neurologic symptoms appear. Pediatricians and neurologists together with ophthalmologists likely collaborate in the diagnosis, evaluation, and care of these children. Nothing is known about the longevity of patients with this condition but because of the loss of ambulation, they require supportive care. Physical therapy may be helpful in the early stages of this disease.
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