Relatively few studies reported on changes in Krebs cycle-related activities, such as pyruvate dehydrogenase and pyruvate kinase in ageing [105], lipoamide dehydrogenase in Alzheimer's disease [138], lipoic acid synthetase in epilepsy [149], and aconitase in Friedreich ataxia [87]. The gene discussed is DLD; the disease is Friedreich ataxia.