Propionic acidemia: case report and review of neurologic sequelae.

We describe late-onset propionic acidemia in a 12-year-old boy who presented with vomiting, cough, and fever, and manifested a precipitous decline in mental status, accompanied by acute encephalopathy and severe neurologic damage, with bilateral basal ganglia involvement upon neuroimaging. He exhibited metabolic acidosis, hyperammonemia, hypocarnitinemia, and elevated plasma glycine. Urinary organic-acid analysis demonstrated very highly elevated 3-hydroxypropionate, propionylglycine, methylcitrate, and tiglylglycine, without an elevation of methylmalonate. Despite intensive medical care, this particular case proved fatal, highlighting the importance of metabolic testing in cases of acute mental-status changes and encephalopathy of unknown etiology.