Mitochondrial complex II deficiency: Difference between revisions

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Overview of Mitochondrial Complex II Deficiency

Mitochondrial Complex II Deficiency

Diagram of Succinate Dehydrogenase, a key component of Complex II

Mitochondrial Complex II Deficiency is a rare metabolic disorder that affects the function of mitochondria, the energy-producing structures within cells. This condition is characterized by a deficiency in the activity of Complex II, also known as succinate dehydrogenase (SDH), which is part of the electron transport chain in mitochondria.

Pathophysiology

Complex II is unique among the complexes of the electron transport chain because it is the only one that participates in both the citric acid cycle and the electron transport chain. It catalyzes the oxidation of succinate to fumarate and transfers electrons to ubiquinone. A deficiency in Complex II disrupts this process, leading to impaired energy production and an accumulation of metabolic intermediates.

Clinical Presentation

Patients with mitochondrial complex II deficiency may present with a variety of symptoms, which can include muscle weakness, hypotonia, developmental delay, and failure to thrive. The severity and range of symptoms can vary widely among affected individuals.

Genetic Basis

Mitochondrial complex II deficiency is often caused by mutations in one of the four nuclear genes that encode the subunits of succinate dehydrogenase: SDHA, SDHB, SDHC, and SDHD. These mutations can be inherited in an autosomal recessive manner.

Diagnosis

Diagnosis of mitochondrial complex II deficiency typically involves a combination of clinical evaluation, biochemical testing, and genetic analysis. Biochemical tests may show reduced activity of succinate dehydrogenase in muscle or liver tissue samples.

Treatment

Currently, there is no cure for mitochondrial complex II deficiency. Treatment is primarily supportive and may include nutritional supplements, physical therapy, and management of symptoms. Research into potential therapies is ongoing.

Related Pages

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-'''Mitochondrial complex II deficiency''', also called '''CII deficiency''', is a rare mitochondrial disease. As of 2013, about thirty-six cases had been reported.<ref name="Sciacovelli">{{cite journal|doi=10.1146/annurev-cancerbio-030419-033612|doi-access=free|title=Metabolic Drivers in Hereditary Cancer Syndromes|year=2020|last1=Sciacovelli|first1=Marco|last2=Schmidt|first2=Christina|last3=Maher|first3=Eamonn R.|last4=Frezza|first4=Christian|journal=Annual Review of Cancer Biology|volume=4|pages=77–97}}</ref>
+{{Short description|Overview of Mitochondrial Complex II Deficiency}}
-==Classification and symptoms==
+== Mitochondrial Complex II Deficiency ==
-Mitochondrial complex II deficiency affects the body's [[mitochondria]]<ref name="GARD">{{cite web|url=https://rarediseases.info.nih.gov/diseases/5053/mitochondrial-complex-ii-deficiency| title=Mitochondrial complex II deficiency| website=Genetic and Rare Diseases Information Center| access-date=25 June 2020}}</ref> and can have a variety of presentations. In some cases, the brain, heart, liver, kidneys, and muscles are affected, while in other cases, only the heart and muscles are affected with adult onset.<ref name="OMIM">{{cite web|url=https://www.omim.org/entry/252011| title=MITOCHONDRIAL COMPLEX II DEFICIENCY| website=OMIM| access-date=25 June 2020}}</ref> Common symptoms include the [[Babinski sign]], muscle weakness, distal [[amyotrophy]] (muscle wasting of the limbs), [[developmental regression]] (loss of developmental milestones), and being easy to fatigue.<ref name="GARD"/>
+[[File:SuccDeh.svg|thumb|right|Diagram of Succinate Dehydrogenase, a key component of Complex II]]
+'''Mitochondrial Complex II Deficiency''' is a rare [[metabolic disorder]] that affects the function of [[mitochondria]], the energy-producing structures within cells. This condition is characterized by a deficiency in the activity of [[Complex II]], also known as succinate dehydrogenase (SDH), which is part of the [[electron transport chain]] in mitochondria.
-==Causes==
+=== Pathophysiology ===
-CII deficiency is a genetic disorder with [[autosomal]] recessive inheritance,<ref name="OMIM"/> meaning that a person must inherit a genetic mutation from each parent to be affected.<ref name="GARD"/>
+Complex II is unique among the complexes of the electron transport chain because it is the only one that participates in both the [[citric acid cycle]] and the electron transport chain. It catalyzes the oxidation of [[succinate]] to [[fumarate]] and transfers electrons to [[ubiquinone]]. A deficiency in Complex II disrupts this process, leading to impaired energy production and an accumulation of metabolic intermediates.
-==Diagnosis==
+=== Clinical Presentation ===
-The most effective way to diagnose CII deficiency is by measuring the activity of [[complex II]] in the muscles.<ref name="OMIM"/>
+Patients with mitochondrial complex II deficiency may present with a variety of symptoms, which can include [[muscle weakness]], [[hypotonia]], [[developmental delay]], and [[failure to thrive]]. The severity and range of symptoms can vary widely among affected individuals.
-==Prognosis==
+=== Genetic Basis ===
-In more severe cases where multiple organ systems are affected, death can occur in early life due to multisystem failure.<ref name="Sciacovelli"/>
+Mitochondrial complex II deficiency is often caused by mutations in one of the four nuclear genes that encode the subunits of succinate dehydrogenase: SDHA, SDHB, SDHC, and SDHD. These mutations can be inherited in an [[autosomal recessive]] manner.
-==References==
+=== Diagnosis ===
-{{reflist}}
+Diagnosis of mitochondrial complex II deficiency typically involves a combination of clinical evaluation, biochemical testing, and genetic analysis. Biochemical tests may show reduced activity of succinate dehydrogenase in muscle or liver tissue samples.
+=== Treatment ===
+Currently, there is no cure for mitochondrial complex II deficiency. Treatment is primarily supportive and may include nutritional supplements, physical therapy, and management of symptoms. Research into potential therapies is ongoing.
+== Related Pages ==
+* [[Mitochondrial disease]]
+* [[Electron transport chain]]
+* [[Succinate dehydrogenase]]
+* [[Metabolic disorder]]
-[[Category:Rare diseases]]
-[[Category:Genetic diseases and disorders]]
 [[Category:Mitochondrial diseases]]
-[[Category:Autosomal recessive disorders]]
+[[Category:Metabolic disorders]]
-{{dictionary-stub1}}