has material basis in germline mutation in SDHA mitochondrial complex II deficiency, nuclear type mitochondrial complex II deficiency, nuclear type 1 https://rarediseases.info.nih.gov/diseases/5053/mitochondrial-complex-ii-deficiency https://www.malacards.org/card/mitochondrial_complex_ii_deficiency GARD:0005053 Orphanet:3208 isolated succinate-CoQ reductase deficiency succinate dehydrogenase deficiency UMLS:C5700310 MONDO:0100294 isolated succinate-ubiquinone reductase deficiency mitochondrial respiratory chain complex II deficiency isolated succinate-coenzyme Q reductase deficiency mitochondrial complex II deficiency, nuclear type 1 SCTID:124165006 MESH:C565375 ICD9:277.6 OMIM:252011 isolated mitochondrial respiratory chain complex II deficiency complex 2 mitochondrial respiratory chain deficiency MEDGEN:1814582 Complex II deficiency is a mitochondrial disease. Mitochondria are specialized compartments in cells that create more than 90% of the energy needed by the body. In mitochondrial diseases, the mitochondria don't work correctly resulting in less energy in the cell, cell injury and cell death. The signs and symptoms of mitochondrial complex II deficiency can vary greatly from severe life-threatening symptoms in infancy to muscle disease beginning in adulthood. Complex II deficiency can be caused by mutations in the SDHA, SDHB, SDHD, or SDHAF1 genes. In many cases the underlying gene mutations cannot be identified. Complex II deficiency is inherited in an autosomal recessive fashion. Complex II deficiency gene mutation carriers may be at an increased risk for certain cancers. DOID:0060537