Succinate Dehydrogenase Deficiency

**Semantic type:** Disease or Syndrome

**Definition:** An autosomal recessive condition characterized by decreased activity of the mitochondrial respiratory chain enzyme complex succinate dehydrogenase (SDH; mitochondrial complex II), which can be caused by loss of function mutation(s) in the any of the genes that encode subunits of SDH. The clinical presentation of this deficiency shows wide variation that ranges from isolated muscle weakness to multisystem symptoms involving the brain, heart and musculoskeletal system with complications such as encephalopathy. Additionally, this condition is associated with an increased risk for cancer because of increased levels of succinate.

**Synonyms:** - Deficiency of Complex II - MC2D - Mitochondrial Complex II Deficiency - Respiratory Complex II Deficiency - SDH Deficiency - SDHx Deficiency - Succinate-CoQ Reductase Deficiency - Succinate-Coenzyme Q Reductase Deficiency