An unusual late-onset case of propionic acidaemia: biochemical investigations, neuroradiological findings and mutation analysis

We report a 5-year-old boy with propionic acidaemia who developed a rapidly fatal necrosis of the basal ganglia after an episode of clinical deterioration. Neither metabolic acidosis nor hyperammonaemia were present. Organic acid analysis in both urine and CSF showed increased levels of methylcitric and 3-hydroxypropionic acids. Propionic acidaemia was confirmed by demonstrating a propionyl-CoA carboxylase deficiency (11% of control value) in skin fibroblasts. DNA analysis revealed that the patient was a compound heterozygote for two mutations in the PCCB gene. Conclusion Propionic acidaemia can present as a sudden and fatal neurological disease and not only as an organic aciduria with severe biochemical dis-turbances and progressive neurological deterioration.