Search

The defect in a newborn with abnormal pyruvate dehydrogenase activity was localized to the X component. Pyruvate dehydrogenase (PDH) is an enzyme complex that is part of the metabolic pathway that extracts energy from carbohydrates. It is composed of three enzymes and a large protein called component X. Component X is believed to form a structure that holds the enzymes in proper orientation. The most common defect is found in enzyme 1. Shortly after birth, the baby developed severe metabolic problems. PDH deficiency was suspected and the baby was placed on a special diet. Enzymatic and genetic analyses of cultured cells found that enzymatic activity was 15% of normal and that the missing component in the complex was the X component. Genetic analysis showed that the gene for enzyme 1 was normal. The mother and father made normal amounts of component X, which suggests a new genetic mutation in the child., Studies of human pyruvate dehydrogenase (PDH) deficiency have shown that defects in the [E.sub.1] component are not common, with only a small number of defects associated specifically with the [E.sub.3], [...]