Methods of treating or suppressing mitochondrial diseases, such asFriedreich's ataxia (FRDA), Leber'sHereditary Optic Neuropathy (LHON), mitochondrial myopathy, encephalopathy,lactacidosis, stroke (MELAS), Kearns- SayreSyndrome (KSS), are disclosed, as well as compounds useful in the methods ofthe invention, such as 2-(3-hydroxy-3-methyl-butyl)-6-(het)aryl-p-quinone or as 2-(3- hydroxy-3-methylbutyl)-3-(het)aryl-p-quinone derivatives. Energy biomarkers useful inassessing the metabolic state of a subject and the efficacy of treatment arealso disclosed. Methods of modulating, normalizing, orenhancing energy biomarkers, as well as compounds useful for such methods, arealso disclosed.
