Interestingly, proteins involved in tricarboxylic acid (TCA) cycle and fatty acid oxidation were up-regulated in COX-negative fibres of both types, compared with COX-positive counterparts, supporting the role of these pathways in driving fibre type-independent metabolic compensatory mechanisms in mitochondrial myopathy [29,30]. The gene discussed is COX5A; the disease is Mitochondrial myopathy.