Isovaleric acidemia in its intermittent variant: diagnostic challenges andvalue of glycine therapy

Isovaleric acidemia is a rare organic acidemia due to a deficiency in isova leryl co-enzyme dehydrogenase, which catalyzes the conversion of isovaleric acid to 3 methyl crotonyl during the degradation of leucine. A chronic int ermittent form of isovaleric acidemia in a four-year-old boy is reported. T here was a history of episodes of vomiting, lethargy, and obnibulation sinc e two weeks bf age; Investigations for a neurological or gastrointestinal c ause were negative. Chromatography of plasma amino acids demonstrated a mod erate increase in the glycine level. Gas chromatography of organic acids sh owed massive accumulation of isovaleryl glycine, thus establishing the diag nosis of isovaleric acidemia. The course was marked by attacks of vomiting and lethargy that were precipitated by stress and infections and responded well to an infusion of parenteral glucose with nothing per os. Following in itiation of a low protein diet with 250 mg/kg/d of glycine, the attacks dec reased in frequency and severity. Early diagnosis and management are essent ial in isovaleric acidemia since appropriate treatment can ensure a favorab le outcome.