It was recently shown that mitochondrial myopathy mouse models with mtDNA replication disorders have increased protein levels of the mitochondrial 1C pathway enzymes MTHFD2 and MTHFD1L, as well as increased transcript levels of the genes encoding for key enzymes of the serine synthesis pathway (Nikkanen et al., 2016). The gene discussed is MTHFD2; the disease is Mitochondrial myopathy.