MT-ND4 and inborn mitochondrial metabolism disorder: To assess the possible therapeutic implications of our observation that central nodes of the nutrient sensing signaling network were modified in primary RC disease, we investigated the mTORC1 and AMPK activities of a FCL from a mitochondrial disease subject (Q1039) who has Leigh syndrome caused by pathogenic mtDNA mutations in two complex I subunit genes (ND4 and ND6).