Chorea and ataxia in propionic acidemia

This boy with propionic acidemia, an inherited disorder caused by a defect of propionyl-CoA carboxylase, displays generalized chorea and a broad-based, unsteady gait. For added stability, he moves about by "bunny hopping" instead of using reciprocal limb movements, and he sits in the "W" position instead of cross-legged. Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme involved in the catabolism of amino acids, odd-chain fatty acids, and other molecules. (Contributed by Dr. Joseph Jankovic.)