MTERF4 and Leigh syndrome: For instance, enhanced serinogenesis has been described in mice carrying a dominant TWINKLE defect, which causes multiple mtDNA deletions [31,32]; in four additional mouse models of impaired mitochondrial DNA maintenance, transcription and translation (i.e., mice defective in TFAM, POLRMT, LRPPRC, or MTERF4) [21]; and in NDUFS1-knockout mice, an animal model of complex I dysfunction mimicking Leigh syndrome [30].