Mitochondrial Complex Ii Deficiency, also known as isolated mitochondrial respiratory chain complex ii deficiency, is related to mitochondrial complex ii deficiency, nuclear type 1 and leigh syndrome, and has symptoms including ataxia, muscle spasticity and myoclonus. An important gene associated with Mitochondrial Complex Ii Deficiency is SDHD (Succinate Dehydrogenase Complex Subunit D), and among its related pathways/superpathways are Respiratory electron transport, ATP synthesis by chemiosmotic coupling, and heat production by uncoupling proteins. and glycolysis (BioCyc). Affiliated tissues include liver and heart, and related phenotypes are spasticity and developmental regression