UNUSUAL PRESENTATIONS OF PROPIONIC ACIDEMIA

The files of 25 patients with propionic acidemia (PA), followed by the Inborn Errors of Metabolism Service (IEMS) at King Faisal Specialist Hospital and Research Centre (KFSHS&RC) from 1990 to 1993, were studie d retrospectively. In 14 patients PA presented acutely with acidosis, hyperammonemia and thrombocytopenia, while in 11 patients the presenta tion of the disease was unusual. In the latter group, two neonates wit h PA initially appeared as a primarily hyperammonemic metabolic diseas e. In two other neonates the vomiting was so severe that they were dia gnosed as intestinal obstruction in referral hospitals. The presentati on in three infants was primarily as an immune disorder. In four infan ts, PA appeared as an acute or chronic encephalopathy, i.e. as a silen t organic acidemia, with few other findings of the disease. The clinic al picture of PA includes facial and nipple dysmorphia, severe hypoton ia and vomiting. Severe thrombocytopenia is the hallmark of the metabo lic crisis. In one patient it was noticed late and caused intracranial hemorrhage, while in three others intracranial bleeding caused death. The prognosis in PA remained grave despite rigorous treatment. Only s even of the 25 PA patients remained to have a normal life-style, while eight patients expired. The diagnosis is readily achieved by urine ga s chromatography/mass spectrometry (GC/MS), by tandem mass spectrometr y (MS/MS), or by enzyme analysis of fibroblasts. While there may be bo th examiner- and patient-related reasons for the variations in the pre sentation of PA, one other reason may be the heterogeneity of the mole cular defect in propionyl-CoA carboxylase.