Respiratory chain deficiencies.

[pyruvate dehydrogenase deficiency]

Mitochondrial functions are intimately associated with neurological symptoms . Various clinical and biological features are suggestive of energy depletion diseases , such as Leigh syndrome , Alpers syndrome , epilepsy (including myoclonic seizures and status epilepticus ), stroke-like episodes , and acute cerebellar ataxia with high lactate peaks on magnetic resonance spectroscopy . Magnetic resonance imaging (MRI ) discloses abnormalities in over 90 % of the cases presenting with neurological symptoms . Basal ganglionic involvement , the most frequent imaging sign , can be isolated or combined with subtentorial atrophy of both the cerebellum and brainstem . MRS monovoxel proton spectroscopy is useful to reveal high lactate spikes if placed in the putamen and the cerebellar dentate nucleus . Lactate and pyruvate levels are required to exclude pyruvate dehydrogenase deficiency . However , lactate may be normal in the CSF . Clinical and biochemical investigations guide molecular studies , with two major heredities : mtDNA point mutations and autosomal recessive defects that program the majority of respiratory chain subunits . Muscle biopsy is the first test demonstrating the histochemical and ultrastructural alterations in mitochondria , even in diseases in which myopathy is not clinically prominent , and is also a good tissue for biochemical analysis , as the biopsy is not dangerous for the patient . Negative results in skeletal muscle do not exclude respiratory chain deficiency , and a liver biopsy may be necessary whatever the blood AST and ALT levels , to perform biochemical and molecular investigations . Only the identification of nuclear or mitochondrial mutation confirms the diagnosis .

Diseases
Validation

Diseases presenting "mitochondrial functions" symptom

inclusion body myositis

pyruvate dehydrogenase deficiency

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