Overview
Definition
An autosomal recessive, progressive neurodegenerative disorder characterized by cerebellar ataxia, sensory neuropathy, hypertrophic cardiomyopathy, and skeletal abnormalities.
Epidemiology
The most common inherited ataxia in Caucasians. Onset typically before 25 years.
Etiology & Risk Factors
- GAA trinucleotide repeat expansion in the FXN gene on chromosome 9, causing deficiency of the mitochondrial protein frataxin, leading to iron overload and oxidative stress
Clinical Symptoms
- Progressive gait and limb ataxia
- Loss of deep tendon reflexes (hyporeflexia/areflexia)
- Dysarthria (slurred speech)
- Loss of vibratory and position sense
- Scoliosis and pes cavus
- Hypertrophic Cardiomyopathy (major cause of death)
- Diabetes Mellitus (in 10% of cases)
Clinical Approach
Diagnosis
- Genetic testing showing GAA repeat expansion in FXN gene
- MRI showing cerebellar and spinal cord atrophy
- Echocardiogram showing hypertrophic cardiomyopathy
Management
- Supportive care, physical therapy, and mobility aids
- Cardiology follow-up for cardiomyopathy
- Management of diabetes
Complications
- Congestive Heart Failure
- Diabetes complications
- Wheelchair dependence