September 9, 2012 — A study of more than 6,000 genes in a common species of yeast has identified the pathways that govern the instability of GAA/TTC repeats. In humans, the expansions of these repeats is known to inactivate a gene – FXN – which leads to Friedreich’s ataxia, a neurodegenerative disease that is currently incurable. In yeast, long repeats also destabilize the genome, manifested by the breakage of chromosomes.