Clinical onset and prognosis of Asian children with organic acidemias, as detected by analysis of urinary organic acids using GC/MS, instead of mass screening.

Organic acidemias (OAs) have been detected worldwide in symptomatic patients using gas chromatography mass spectrometry. We diagnosed 188 Asian cases of OAs by analysis of urinary organic acids and investigated their clinical onset and outcome. Methylmalonic acidemia (MMA) was most common (74 cases), followed by propionic acidemia (23 cases), ornitine transcarbamylase deficiency (22 cases), and multiple carboxylase deficiency (15 cases). For these 188 patients, onset was most frequent in the neonatal period or early infancy. Approximately 30% of the patients had a family history of similar symptoms or diseases. Although the outcome of OA patients varied, patients with early onset generally had poor outcomes despite early detection. Of the 45 MMA patients whose clinical data were available, 25 were clinically vitamin B12-responsive, while the remaining 20 were non-responsive. A favorable outcome was obtained in 7 of the 25 B12-responsive patients, and in only 3 of the 20 B12-nonresponsive patients. It was suggested that even in B12-responsive MMA cases, earlier detection and B12 therapy were needed to improve the prognosis. We concluded that detection of such patients at the presymptomatic stages using newborn mass screening is essential for prognosis improvement with OAs.