Friedreich's ataxia is a debilitating, life-shortening, neurodegenerative disorder. It is characterized by progressive damage to the nervous system, leading to symptoms such as gait disturbance, muscle weakness, and heart disease.

It primarily affects the corticospinal tracts, spinocerebellar tracts, dorsal columns, and peripheral nerves.

Epidemiology

Friedreich's ataxia, though a rare condition, is the most common inherited ataxia, with an incidence of approximately 1 in 40,000 in the general population. Both sexes are equally affected, and symptoms typically onset in childhood to early adulthood, usually between the ages of 5 and 15.

Aetiology

• Friedreich's ataxia is an autosomal recessive disorder, caused by a trinucleotide (GAA) repeat expansion within the first intron of the frataxin gene on chromosome 9.
• The result is decreased synthesis of frataxin, a protein that is essential for mitochondrial iron homeostasis.
• Insufficient frataxin levels lead to iron accumulation and resultant oxidative stress, which contributes to neuronal and muscle cell death.

PC

• Neurological symptoms: lower limb weakness, gait abnormalities, frequent falls, cerebellar signs (ataxia, dysarthria, dysmetria, etc.), and mixed upper and lower motor neuron signs such as absent knee/ankle reflexes and upgoing plantars.
• Sensory symptoms: impaired joint position and vibration sense due to dorsal column involvement.
• Physical signs: high-arched palate, pes cavus (high arch of the foot), and kyphoscoliosis.
• Non-motor features: hypertrophic obstructive cardiomyopathy, reduced visual acuity, type 1 diabetes mellitus, and deafness.

Differential diagnosis

• Spinocerebellar ataxia: progressive ataxia, nystagmus, dysarthria, but typically presents in adults.
• Ataxia Telangiectasia: presents with cerebellar ataxia, telangiectasias, immunodeficiency, and increased risk of malignancy.