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 (KFSH & RC) from 1990 to 1993, were studied retrospectively. In 14 patients PA presented acutely with acidosis, hyperammonemia and thrombocytopenia, while in 11 patients the presentation of the disease was unusual. In the latter group, two neonates with PA initially appeared as a primarily hyperammonemic metabolic disease. In two other neonates the vomiting was so severe that they were diagnosed as intestinal obstruction in referral hospitals. The presentation in three infants was primarily as an immune disorder. In four infants, PA appeared as an acute or chronic encephalopathy, i.e. as a silent organic acidemia, with few other findings of the disease. The clinical picture of PA includes facial and nipple dysmorphia, severe hypotonia and vomiting. Severe thrombocytopenia is the hallmark of the metabolic 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 seven of the 25 PA patients remained to have a normal life-style, while eight patients expired. The diagnosis is readily achieved by urine gas chromatography/mass spectrometry (GC/MS), by tandem mass spectrometry (MS/MS), or by enzyme analysis of fibroblasts. While there may be both examiner- and patient-related reasons for the variations in the presentation of PA, one other reason may be the heterogeneity of the molecular defect in propionyl-CoA carboxylase.

4-Hydroxybutyric aciduria

The clinical findings in six patients from three families with 4-hydroxybutyric aciduria are described. The onset of disease was in early infancy in all cases. All infants presented with severe global delay and severe hypotonia, and all patients had seizure disorder. Eye findings included optic atrophy in two patients, and retinitis pigmentosa in one. Three patients had choreoathetosis, two had myoclonus and one had severe dystonia. The urine 4-hydroxybutyric acid was 300-1000 times that of normal, and other organic acids related to its further metabolism or to its inhibitory effect on beta-oxidation were also increased. The administration of vigabatrine rapidly reduced the excretion of 4-hydroxybutyric acid promptly, and in the long-term its excretion could be kept at 80-200 times that of normal. However, the clinical course of the disease improved in only two, remained the same in two, and worsened in the remaining two patients.

Comparative frequency and severity of hypoglycemia in selected organic acidemias, branched chain amino acidemia, and disorders of fructose metabolism

The Institution's experience with hypoglycemia in different types of organic acidemias, branched chain amino acidemia (MSUD), and disorders of fructose metabolism was reviewed retrospectively. The charts of 144 patients who were followed for 1-5 years were studied for the severity and frequency of hypoglycemia. The patients were mainly Saudi; however, 10-25% were from neighboring countries. Therefore, the observations pertain to the genetic groups in the Arabian peninsula. Organic acidemias which primarily manifest with neurologic signs, such as 4-hydroxybutyric aciduria, infantile onset 3-methylglutaconic aciduria, and glutaric aciduria type 1 never showed hypoglycemia. Patients with beta-ketothiolase deficiency, biotinidase deficiency, or intermittent or intermediate MSUD, also did not have hypoglycemia during metabolic crisis. Hypoglycemia was rare and mild among neonates with classic MSUD, ethylmalonic aciduria, and isovaleric acidemia. Less than 50% of the patients with MSUD older than 8 months, pyruvate carboxylase deficiency, methylmalonic acidemia, or propionic acidemia had hypoglycemia during metabolic crisis. On the other hand, patients with 3-hydroxy-3-methyl glutaryl-CoA lyase deficiency, holocarboxylase synthetase deficiency, medium or long-chain acyl-CoA dehydrogenase deficiency, neonatal onset 3-methylglutaconic aciduria, glutaric aciduria type 2, and disorders of fructose metabolism invariably had moderate-to-severe hypoglycemia associated with metabolic crisis. The purpose of this report is to provide the pediatrician, particularly in the Middle East, with a diagnostic guideline to the identification and management of different types of organic acidemias, based on co-existing hypoglycemia.

A new patient with alpha-ketoglutaric aciduria and progressive extrapyramidal tract disease

A 4.5-year-old boy with chronic progressive encephalopathy is described. The clinical presentation initially included seizures and hypotonia which later evolved into severe extrapyramidal disease and dementia. The gas chromatography/mass spectrometry (GC/MS) analysis of urine indicated that alpha-ketoglutarate was increased 210 times and aconitic acid 80 times. No disturbance of acid/base balance, lactic acid or ammonia metabolism accompanied this clinical picture. The fibroblasts contained 29% of normal alpha-ketoglutarate dehydrogenase activity, while the activity of another mitochondrial marker enzyme, glutamate dehydrogenase, was normal. The neuroimaging studies revealed bilateral striatal necrosis. The clinical and biochemical findings were almost identical to two previously reported patients. Experience with this patient emphasizes the need for detailed organic acid biochemical investigation in any progressive encephalopathy and that extrapyramidal tract signs should evoke the possibility of alpha-ketoglutaric aciduria, among other 'neurologic organic acidemias'.