FXN and Friedreich ataxia: The level of FXN mRNA and FXN protein in GAA/PM fibroblasts was ∼7-fold lower compared to unaffected control fibroblasts lacking expanded GAAr and comparable with the level of FXN mRNA and protein found in FRDA fibroblasts derived from a patient with bi-allelic GAAr expansion (GAA/GAA) (Figures 1C–1E).