A boy with a hereditary defect of pyruvate decarboxylase has had intermittent ataxia, often with choreoathetosis, following fever or excitement, and lasting several days, but is clinically normal between attacks. There were excessive lipid droplets in his skeletal muscle. Blood, urine, and cerebrospinal fluid pyruvate levels were increased as were blood and urine alanine levels but blood lactate levels were rarely abnormal. Pyruvate levels tended to be higher during an attack, and then, more abnormal (as were the clinical signs) in the late afternoon. Dexamethazone (Decadron) relieved the attacks without affecting blood pyruvate. Thiamine had little effect although attack frequency declined after 19 months of treatment. This disorder, in which a constant metabolic defect predisposes to intermittent symptoms, may provide a model for understanding the relations between genetic and environmental factors in other diseases.
Blass JP, Kark RAP, Engel WK. Clinical Studies of a Patient With Pyruvate Decarboxylase Deficiency. Arch Neurol. 1971;25(5):449–460. doi:10.1001/archneur.1971.00490050083007
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