FXN GAA repeat expansions in amyotrophic lateral sclerosis

FXN GAA repeat expansions in amyotrophic lateral sclerosis. Naji Rizik, Axel Freischmidt, Albert C. Ludolph, Jochen H. Weishaupt; ournal of Clinical Neuroscience, Available online 27 January 2014. http://dx.doi.org/10.1016/j.jocn.2013.10.029

When homozygously present, an increased number of GAA repeats in the FXN gene results in a severely decreased expression of frataxin, resulting in the manifestation of FRDA. However, even heterozygous expansion of the trinucleotide repeat substantially reduces frataxin expression. Heterozygous expansion carriers are usually normal, but still display an increased risk for pathological glucose tolerance and, thus suggesting that a heterozygous FXN mutation leads to a borderline impairment of specific cell types at risk.