FXN and Friedreich ataxia: In children with Friedreich ataxia, observing lower levels of frataxin appears to be a useful indicator in confirming the diagnosis and monitoring the efficacy of potentially available treatments, but further studies are needed to confirm their utility (including type of tissue and cut-offs). In children with Friedreich ataxia, measuring le levels of cardiac troponin seems to be useful in monitoring cardiac complications, but further studies are needed to confirm its utility.