Friedreich ataxia (https://omim.org/entry/229300) is an autosomal recessive neurodegenerative disorder characterized by progressive gait and limb ataxia with associated limb muscle weakness, absent lower limb reflexes, extensor plantar responses, dysarthria, and decreased vibratory sense and proprioception. Onset is usually in the first or second decade, before the end of puberty. It is one of the most common forms of autosomal recessive ataxia, occurring in about 1 in 50,000 individuals. Other variable features include visual defects, scoliosis, pes cavus, and cardiomyopathy (review by Delatycki et al., 2000).
Pandolfo (2008) provided an overview of Friedreich ataxia, including pathogenesis, mutation mechanisms, and genotype/phenotype correlation.