Epigenetic regulation of clinical manifestations of Friedreich's disease

Abstract

To study a methylation profile of FXN gene and its influence on the clinical phenotype of Friedreich's desease (FD). The methylation pattern was analyzed in 17 patients with FD. Forty-five CpG-sites in the promoter region and the region of intron 1 of FXN: before the GAA-expansion (UP-GAA) and after the GAA-expansion (DOWN-GAA), were studied. Correlations between the methylation level of CpG-sites in UP-GAA and DOWN-GAA and the number of GAA repeats in both expanded FXN alleles in patients with FD were found. An analysis revealed an earlier onset and a more severe course of FD in cases with hypermethylation of several CpG-sites in the UP-GAA region. The correlation between the methylation pattern and the presence of extraneural manifestations of FD was also revealed. In FD patients with cardiomyopathy, a hypomethylated CpG-site in the promoter region was found. In FD patients with carbohydrate metabolism disorders, two hypomethylated CpG-sites in the DOWN-GAA region were observed. The results indicate a significant contribution of epigenetic modifications of FXN to the clinical presentation of FA.