FXN and Friedreich ataxia: It has been shown that a number of pathogenic mutations that produce Friedreich’s ataxia involves protein variants that are highly destabilized showing significantly lower melting temperatures and lower free energy of unfolding by comparison to the wild-type FXN, among them: G130V (ΔTm = 23 °C and ΔΔG°NU ∼2.9 kcal mol−1)31, G137V (ΔTm ~20 °C)32 and L198R (ΔTm = 15.3 °C and ΔΔG°NU ∼4.2 kcal mol−1)5.