Pyruvate dehydrogenase deficiency
is metabolic disorder associated with abnormal function of the mitochondria in cells, thus depriving the body of energy. Progressive neurological symptoms usually start in infancy but may be evident at birth, or in later childhood; these symptoms may include developmental delay, intermittent ataxia, poor muscle tone (hypotonia), abnormal eye movements, or seizures. Severe lethargy, poor feeding, and tachypnea (rapid breathing) commonly occur, especially during times of illness, stress, or high carbohydrate intake. Childhood-onset forms of the condition are often associated with intermittent periods of illness but normal neurological development. Prognosis is difficult to predict due to the many causes of the condition, but in most cases of neonatal and infantile onset, prognosis is described as poor. The most common form of pyruvate dehydrogenase deficiency is caused by mutations in the E1 alpha gene, and is inherited in an X-linked dominant manner; all other forms are caused by various genes and are inherited in an autosomal recessive manner. In addition to directly treating acidosis and providing alternative energy for the body, treatment typically includes dietary supplementation with thiamine, carnitine, and lipoic acids, although not all individuals respond to this therapy. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.