Treatment and prognosis of developmental delay in children caused by inborn errors of metabolism

Objectives To investigate the treatment and prognostic factors of developmental delay in children caused by inborn errors of metabolism. Methods Two hundred and seventy-eight patients with developmental delay were enrolled in the study. Blood amino acids and acylcarnintines profiles were tested with tandem mass spectrometry. Gas chro- matography / mass spectrometry (GC / MS) analysis of urine and enzyme activity tests were further made when the patients were suspected to have metabolic disorders. Clinical data of the patients with inborn errors of metabolism were also ana- lyzed. Results Seventeen of 278 patients (6.15% ) with metabolic disorders were confirmed, including methylmalonic acidemia (MMA)(4), methylmalonic acidemia complicated with homocystinuria (4), propionic acidemia (PA) (3), ornithine transcarbamylase deficiency (1), maple syrup urine disease (1), glutaric acidemia typeⅠ (1), metachromatic leukodystrophy (MLD)(1), phenylketonuria (1), and biotinidase deficiency (1) . The clinical manifestations were di- verse, including mental retardation or regression, seizure, coma, vomiting, hypotonia, malnutrition, lethargy, frequent infections, etc. Laboratory findings included metabolic acidosis, hyperammonemia, hyperlacticemia, and anemia. MRI findings included cerebral atrophy, a pattern of T2 higher signal intensity and / or T1 lower signal intensity in cerebral white matter and multiple encephalomalacia or cystic changes, etc. MMA patients, early-onset with severe acidosis and coma, with no response to the treatment of vitamin B12, had a poor prognosis. Improvement was observed in 11 patients after treatment with special milk, low-protein diet, carnitine, vitamin B12 and biotin, etc. Four MMA patients and 1 PA pa- tients died, 1 MLD patient unchanged. Conclusions Screening tests of inherited metabolic disorders should be performed in children with developmental delay with unknown etiology. Early diagnosis and appropriate treatment might improve the prognosis.