Spinocerebellar Ataxia, Autosomal Recessive 7
Patient Information
Characteristics
Background and History
This is a recently reported progressive neurological disease primarily affecting balance and walking.
Clinical Correlations
Symptoms begin in late childhood or early teenage years with unsteadiness and mild difficulties walking. These symptoms are slowly progressive and, while many adults function well into their 40s, some become wheelchair-bound in the next decade or two. Fine hand movements are impaired and there may be a mild tremor. Reflexes are abnormally brisk and the sense of touch may be diminished. Vision is usually not impaired but eye movements are often jerky (nystagmus). There is no significant cognitive impairment.
Genetics
Inheritance
This is an autosomal recessive condition whose expression requires the presence of two changed copies of a gene (mutations). Affected children inherit one mutated copy from each parent who is clinically normal. Each child in such a family has a risk of 25% of inheriting this spinocerebellar atrophy.
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
This condition can be diagnosed by a neurologist when evaluated for balance and mobility problems. Eye movement problems (nystagmus) may lead to referrals to an ophthalmologist. Because SCAR7 is only one of multiple disorders with similar signs and symptoms, a full clinical and imaging evaluation is usually done.
SCAR7’s impact on longevity is unknown and no effective treatment is available for the neurological condition. However, physical therapy and mobility devices could be helpful for tasks of daily living. Speech therapy might be helpful for the dysarthria.
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