An excellent illustration of this observation is the fact that TP expression in skeletal muscles is absent, nonetheless, some but not all MNGIE cases were reported with skeletal muscle mtDNA deletions, histological and oxidative phosphorylation abnormalities (Papadimitriou et al., 1998; Hirano et al., 2004). The gene discussed is TYMP; the disease is mitochondrial neurogastrointestinal encephalomyopathy.