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Disruption of the metabolism of pyruvate
Last reviewed: 23.04.2024
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Deficiency of pyruvate dehydrogenase
Pyruvate dehydrogenase is a multienzyme complex responsible for the formation of acetylCoA from pyruvate for the Krebs cycle. Deficiency of this enzyme leads to an increase in the level of pyruvate and therefore an increase in the level of lactic acid. The type of inheritance is X-linked or autosomal-recessive.
Symptoms vary in severity, but always include lactatacidosis and structural abnormalities of the central nervous system and other postnatal changes, including cystic changes in the cerebral cortex, brainstem and basal ganglia; ataxia and delayed psychomotor development. The diagnosis is confirmed by the study of skin fibroblast enzymes, DNA testing or a combination thereof. There is no unequivocally effective treatment, although for some patients low-carbohydrate diet and additional administration with thiamine food were effective.
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Deficiency of pyruvate carboxylase
Pyruvate carboxylase is an enzyme important for gluconeogenesis from pyruvate and alanine, which are formed in muscles. Deficiency can be primary or secondary due to a deficiency of synthetase of holocarboxylase, biotin or biotinidase; inheritance in both cases is autosomnostessive and in both cases lactatacidosis develops.
The primary deficit rate is less than 1/250 000 births, but may be higher among certain populations of American Indians. The main clinical manifestations are the delay of psychomotor development with convulsions and spasticity. Laboratory changes include hyperammonemia; lactic acidosis; ketoacidosis; elevated levels of lysine, citrulline, alanine and proline in plasma, as well as increased excretion of alpha -ketoglutarate. The diagnosis is confirmed by the study of enzymes in the culture of skin fibroblasts.
The secondary deficit is clinically similar to the primary one, with the development of hypotrophy, seizures and other organic aciduria.
There is no effective treatment, however, individual patients with a primary deficit, as well as all patients with a secondary deficit should be administered biotin by 5-20 mg once a day.