The packet does not certify a gene for this condition, so no gene is named here, and its structured inheritance field is empty; the genetic detail below is drawn from GeneReviews text. GeneReviews describes the condition as autosomal recessive, usually caused by inheritance of an expanded GAA repeat allele from both parents. It states that approximately 96% of individuals have biallelic GAA repeat expansions in intron 1 of the causative gene, and approximately 4% are compound heterozygotes for a repeat expansion and either a sequence variant or a large deletion. GeneReviews classifies repeat sizes as normal (5-33 repeats), intermediate (34-65), borderline (44-65), and pathogenic with full penetrance (66 to approximately 1,300).

GeneReviews states that penetrance is complete for biallelic pathogenic repeat sizes or compound heterozygosity, that onset can range from younger than age five years to older than age 50 years, and that variability in onset can occur within the same sibship. It notes that reduced penetrance may be associated with borderline alleles. Heterozygous carriers are described as asymptomatic and not at risk of developing the disorder. When both parents are heterozygous, each sibling of an affected individual has at conception a 25% chance of inheriting biallelic alterations, a 50% chance of inheriting one alteration, and a 25% chance of inheriting neither.

GeneReviews states that no consensus diagnostic criteria for Friedreich ataxia have been published. It lists suggestive clinical features: progressive ataxia, dysarthria, decreased or lost position and vibration sense in the lower limbs, pyramidal involvement, muscle weakness, scoliosis, pes cavus, hypertrophic non-obstructive cardiomyopathy, glucose intolerance or diabetes mellitus, and optic atrophy or deafness, with neurologic onset typically but not always before age 25 years. Brain MRI is often normal in early stages; with advanced disease, atrophy of the cervical spinal cord and cerebellum may be observed. A family history consistent with autosomal recessive inheritance is described as supportive, and absence of a known family history does not preclude the diagnosis.

According to GeneReviews, the diagnosis is established in a proband with biallelic pathogenic or likely pathogenic variants identified by molecular genetic testing, and identification of a heterozygous variant of uncertain significance does not establish or rule out the diagnosis. The packet does not contain a newborn screening field for this condition.

GeneReviews states that there is no cure for FRDA. The packet lists one FDA-approved treatment with active market status: Skyclarys (omaveloxolone), approved under an NDA on 2023-02-28. GeneReviews describes omaveloxolone as approved in the United States and Europe for individuals age 16 years and older, as shown to slow progression of FRDA, and as generally well tolerated, with the main side effects noted being alterations in liver function that are generally of short duration and increases in serum lipids that sometimes require therapy.

Supportive care. GeneReviews describes supportive care to improve quality of life, maximize function, and reduce complications, ideally through multidisciplinary care by specialists such as neurologists, ophthalmologists, orthoptists, physical and occupational therapists, cardiologists, endocrinologists, speech-language therapists, and psychologists. Its treatment table addresses ataxia, spasticity, scoliosis, dysarthria, dysphagia, cardiac disease, and bladder dysfunction.

Surveillance. GeneReviews lists a surveillance table that includes neurology evaluation with a standardized ataxia scale at a minimum annually, annual cardiac evaluation when initial EKG and echocardiogram are normal, annual endocrine evaluation for diabetes mellitus, and hearing assessment every 2-3 years.

Other designations. The packet lists orphan drug designations for many investigational products, including gene therapy and small-molecule candidates; designation is distinct from approval, and several records (for example idebenone and deferiprone) carry WITHDRAWN status.

The packet does not certify a structured natural history field or life expectancy data. The packet definition states that ataxia worsens over time. GeneReviews describes a progressive course in which gait ataxia, present in all individuals, is typically the earliest manifestation, and within five years of onset most individuals exhibit dysarthria, lower-extremity weakness, and diminished or absent joint position and vibration sense. GeneReviews states that dysphagia severity correlates with disease duration and severity, that the size of the cervical spinal cord correlates with disease severity, and that age at onset varies widely.

The packet records 33 clinical trials for Friedreich ataxia, all counted as active. Listed records include a Phase 3 study of subcutaneous nomlabofusp (NCT07778836; Larimar Therapeutics; recruiting), a Phase 3 long-term study of vatiquinone (NCT07681713; PTC Therapeutics; not yet recruiting), a Phase 1 study of SGT-212 gene therapy (NCT07180355; Solid Biosciences; recruiting), a Phase 2 study of LX2006 gene therapy for cardiomyopathy (NCT07721025; Lexeo Therapeutics; recruiting), and a natural history study (NCT06016946; Friedreich's Ataxia Research Alliance; recruiting). Registry records describe studies, not outcomes.

GeneReviews describes therapies under investigation as including approaches aimed at increasing frataxin levels (nomlabofusp, DT-216P), mitochondrial function and oxidative stress (vatiquinone, nicotinamide riboside, elamipretide), gene therapy using viral vectors (LX2006), modulation of frataxin-controlled pathways (leriglitazone, dimethyl fumarate), and rehabilitation. The packet's research digest classifies 362 publications, with basic science and preclinical work as the dominant type. The Friedreich's Ataxia Research Alliance (FARA) is listed as a patient organization with a registry.