This report describes general characteristics of the group of diseases classified as mitochondrial complex III deficiency, nuclear type (MC3DN). MC3DN is a genetically heterogeneous disorder, with multiple genes and mapped loci. A comprehensive list of MC3DN subtypes, as defined by OMIM, can be found by following the link in the "OMIM phenotypic series" section, below. A subset of these are listed in the table below, with links to more detailed reports for subtypes that have been investigated using fly models.
Mitochondrial complex III (ubiquinol-cytochrome c reductase complex; bc1 complex), the third enzyme complex in the mitochondrial respiratory electron transport chain, is a multisubunit transmembrane protein encoded by both the mitochondrial (cytochrome b) and the nuclear genomes (all other subunits). This phenotypic series includes only diseases caused by dysfunction of nuclear-encoded proteins, including protein chaperones required for complex III assembly.
[updated Sep. 2021 by FlyBase; FBrf0222196]
Autosomal recessive mitochondrial complex III deficiency is a severe multisystem disorder with onset at birth of lactic acidosis, hypotonia, hypoglycemia, failure to thrive, encephalopathy, and delayed psychomotor development. Visceral involvement, including hepatopathy and renal tubulopathy, may also occur. Many patients die in early childhood, but some may show longer survival (de Lonlay et al., 2001, pubmed:11528392; De Meirleir et al., 2003, oubmed:12910490 ). [from MIM:124000; 2021.09.26]
Mitochondrial complex III deficiency can be caused by mutation in several different nuclear-encoded genes. [from MIM:124000; 2021.09.26]
