The disease is progressive, with increasing staggering or stumbling gait and frequent falling. By the third decade, affected people lose the ability to stand or walk without assistance and require a wheelchair for mobility. Early-onset cases
Non-neurological symptoms such as scoliosis, pes cavus, cardiomyopathy and diabetes are more frequent amongst the early-onset cases. Genetics
FRDA is an autosomal-recessive disorder that affects a gene (FXN) on chromosome 9, which produces an important protein called frataxin.In 96% of cases, the mutant FXN gene has 90–1,300 GAA trinucleotide repeat expansions in intron 1 of both alleles. This expansion causes epigenetic changes and formation of heterochromatin near the repeat. The length of the shorter GAA repeat is correlated with the age of onset and disease severity. The formation of heterochromatin results in reduced transcription of the gene and low levels of frataxin. People with FDRA might have 5-35% of the frataxin protein compared to healthy individuals. Heterozygous carriers of the mutant FXN gene have 50% lower frataxin levels, but this decrease is not enough to cause symptoms.In about 4% of cases, the disease is caused by a (missense, nonsense, or intronic) point mutation, with an expansion in one allele and a point mutation in the other. A missense point mutation can have milder symptoms. Depending on the point mutation, cells can produce no frataxin, nonfunctional frataxin, or frataxin that is not properly localized to the mitochondria. Pathophysiology
FRDA affects the nervous system, heart, pancreas, and other systems.Degeneration of nerve tissue in the spinal cord causes ataxia.
A supernumerary  kidney is an additional kidney to the number usually present in an organism. This often develops as the result of splitting of the nephrogenic blastema, or from separate metanephric blastemas into which partially or completely reduplicated ureteral stalks enter to form separate capsulated kidneys; in some cases the separation of the reduplicated organ is incomplete (fused supernumerary kidney). Less than a hundred cases are known of one or two supernumerary kidneys. See also
Supernumerary body part

References
Luciano A. Favorito; Ana Raquel M. Morais (May–June 2012). "Evaluation of supernumerary kidney with fusion using magnetic resonance image". IBJU. 38 (3): 428–429. doi:10.1590/s1677-55382012000300018. PMID 22765860.