Spinocerebellar Ataxia 3

Background and History: 

This is one of a group of inherited disorders with a progressive deterioration of the nervous system.  Symptoms of balance difficulties and abnormal eye movements causing double vision are among the most prominent.  It is sometimes referred to as Machado-Joseph disease.

Clinical Correlations: 

Onset of symptoms in this progressive condition is noted by young adults usually by the fourth decade although there is considerable variation.  General clumsiness, some slurring of speech, and an unsteady gait are among the first symptoms.  Many individuals complain of blurry vision and double vision about the same time.  Eye movements become 'jerky' and with time they slow down leaving the eyes in a relatively fixed position and patients may be unable to look up.  Difficulty swallowing, loss of touch sensations, tremors, and some rigidity of movement eventually occur.  About a decade after the onset of symptoms many patients need assistive devices such as wheelchairs to ambulate.

Special studies such as MRIs and nerve conduction studies can be useful in the diagnosis but gene testing is necessary to make the specific diagnosis.


This is an autosomal dominant disorder with family pedigrees showing a vertical pattern of transmission from one generation to the next.  The children of parents with this condition have a 50% risk of developing this disorder.

Diagnosis and Prognosis: 

This form of spinocerebellar ataxia cannot be clinically diagnosed at birth and requires testing for the presence of the appropriate mutation.  When symptoms appear, usually in the fourth decade, collaboration among general physicians, radiologists, and neurologists is required to fully delineate the signs and symptoms. Gene testing is necessary to categorize the type of spinocerebellar ataxia present.

There is no effective treatment for the general disorder.  However, low vision aids as well as physical and occupational therapy combined with regular exercise are considered helpful in slowing the progression of symptoms.  However, lifespan is generally shortened with most patients succumbing to the disease within several decades of the onset of symptoms.

Additional Information
Autosomal dominant