Friedreich ataxia

What it is

Friedreich ataxia is a 'spinocerebellar' degeneration in pathological terms — although the cerebellum is involved later, the earliest and heaviest pathology is in the dorsal root ganglia and the spinocerebellar and corticospinal tracts. This explains the characteristic clinical signature of cerebellar ataxia combined with sensory ataxia (loss of joint-position and vibration sense) and corticospinal signs (extensor plantars), all with absent deep tendon reflexes in the legs.

The GAA expansion in the first intron of FXN silences gene transcription through heterochromatin formation, producing reduced frataxin protein. Frataxin is essential for mitochondrial iron-sulphur cluster biogenesis. Its loss impairs mitochondrial complex I, II and III activity; iron accumulates in mitochondria; oxidative stress rises. Cells with the highest energetic demand — neurons, cardiac myocytes, pancreatic beta-cells — suffer first.

How it presents

A typical child presents between 8 and 15 with one of the following patterns:

• Progressive gait ataxia — first noted as clumsiness in sport, then frank balance difficulty
• A foot deformity (pes cavus, hammer toes) brought to attention by an orthopaedic surgeon
• Scoliosis identified at school screening — often progresses rapidly during puberty
• Hypertrophic cardiomyopathy found on ECG or echo done for another reason
• Areflexia detected at a school screening or family-doctor visit
• Bilateral hearing loss or visual deterioration (rare presenting feature)

Diagnosis

Diagnosis is genetic: a triplet-repeat primed PCR (TP-PCR) for GAA expansion in FXN intron 1 is the targeted test. A repeat length above 66 on both alleles confirms the diagnosis; in many laboratories the cut-off is reported as expanded if >66, with disease severity broadly correlated with the size of the shorter allele (smaller expansions → milder, later-onset disease). About 4% of patients are compound heterozygous, with one expansion and one point mutation, and need sequencing if TP-PCR shows only one expansion.

Brain MRI shows minor cerebellar atrophy late in disease; spinal MRI may show atrophy of the cervical cord. Nerve conduction studies show a sensory axonal neuropathy. Echocardiogram typically shows concentric hypertrophic cardiomyopathy or, later, dilated cardiomyopathy. HbA1c and glucose monitor for diabetes.

Current treatment

Until 2023, treatment was symptomatic and supportive only. The landscape has changed rapidly:

• Omaveloxolone (Skyclarys, Reata/Biogen) — Nrf2 activator that promotes mitochondrial biogenesis and antioxidant response. FDA-approved February 2023 for patients age 16 and older with Friedreich ataxia, based on the MOXIe Phase 2 trial showing a meaningful slowing of disease progression at 48 weeks. EMA approval February 2024. Paediatric trials (MOXIe extension and follow-on) are extending eligibility to under-16s, expected from 2025–2026
• Supportive cardiology — annual echo and ECG; ACE inhibitor or beta-blocker for symptomatic cardiomyopathy; arrhythmia surveillance
• Diabetes management — onset typically in second or third decade; standard insulin/oral hypoglycaemics
• Physiotherapy and occupational therapy — central to maintaining mobility, transfers, fine motor function; wheelchair use typically 10–15 years after onset
• Orthopaedic — scoliosis surgery for severe curves; foot surgery for fixed deformity
• Speech and language therapy — for dysarthria; communication aids in advanced disease
• Mental health support — depression is common and under-recognised

Disease-modifying programmes in development

After omaveloxolone, several next-generation approaches are in active development:

• AAV gene-replacement therapies (Lexeo Therapeutics LX2006, Solid Biosciences SGT-212) — early-phase trials of cardiac-targeted gene therapy showing safety and exploratory efficacy signals
• CRISPR-based epigenome editing (TaRGET-CT, Epic Bio) to reactivate the silenced FXN allele — preclinical
• Recombinant frataxin protein replacement strategies — preclinical
• Antisense and small-molecule approaches to lift the GAA-induced heterochromatin silencing — early clinical

Prognosis

Friedreich ataxia is progressive. Most patients lose independent ambulation about 10–15 years after onset, and median survival has historically been around 35–40 years, with hypertrophic cardiomyopathy the leading cause of death. The introduction of omaveloxolone, the expanding cardiac monitoring strategies, and the gene-therapy programmes mean the next two decades are likely to look very different from the past.

How an educational review can help

Friedreich ataxia families navigate complex decisions about omaveloxolone eligibility, cardiac surveillance, scoliosis surgery timing and trial participation. An educational review can place a young person against the most recent evidence, explain where the trials stand, and help prepare focused questions for the treating cardiology, neurology and metabolic teams.

It is an educational second opinion — not a diagnosis, treatment or prescription — and it does not replace the care of your child's own clinicians.