- Clinical science
Friedreich ataxia (FDRA) is an autosomal recessive disorder involving trinucleotide repeat expansion that leads to progressive neurodegeneration. It affects multiple spinal cord tracts, causing muscle weakness and impaired coordination of all limbs. A staggering gait in childhood is the resulting main symptom. Other features include skeletal abnormalities, cardiomyopathy, and diabetes. The clinical course is mainly determined by the extent of the loss of mobility and cardiac involvement. Diagnosis requires confirmation with genetic tests. Because there is no curative therapy available, the prognosis is poor.
- The most common autosomal recessive ataxia
- Peak incidence: 8–15 years (most cases < 25 years)
- Most common in white populations
Epidemiological data refers to the US, unless otherwise specified.
Progressive ataxia (muscle weakness and impaired coordination) of all limbs
Bilateral lower limbs equally affected
- Wide-based steppage gait with dysmetria and frequent falling
- Titubation while standing or sitting
- Torso and arms
- Action and intention tremors
- Choreiform movements
- Associated impaired proprioception, vibration sense (pallhypesthesia), and loss of deep tendon reflexes
- Bilateral lower limbs equally affected
- Dysarthria and dysphagia (may be accompanied by uncoordinated breathing)
- Progressive ataxia (muscle weakness and impaired coordination) of all limbs
- Skeletal deformities
- Concentric : palpitations, arrhythmias, dyspnea, exercise intolerance
- Diabetes mellitus
- Personality changes (e.g., emotional lability)
- A specific trinucleotide repeat expansion assay should be performed in all suspected cases.
- ECG: T-wave inversion and ventricular hypertrophy
- Echocardiography: symmetric, concentric ventricular hypertrophy
Nerve conduction studies
- Sensory: absent or reduced sensory nerve action potentials (SNAP)
- Motor: normal until advanced stages
- MRI brain and spinal cord: cervical spine atrophy (minimal cerebellar atrophy)
- No curative treatment available
- Multidisciplinary supportive care: genetic counseling, physiotherapy, and speech and language therapy
- Treatment of cardiologic, orthopedic, and metabolic (i.e., diabetes) features of the disease
- Carrier testing of relatives
- Prenatal testing: Genetic counseling is recommended for parents with one affected child.