Diagnosis of peroxisomal disorders by analysis of phytanic and pristanic acids in stored blood spots collected at neonatal screening.

Concentrations of phytanic acid and pristanic acid were measured in stored dried blood spots collected at neonatal screening from patients with peroxisomal disorders, and compared with concentrations in control blood spots. In blood spots from two patients with Zellweger syndrome both phytanic acid and pristanic acid concentrations were increased but their concentration ratio was normal. In the blood spot from a patient with rhizomelic chondrodysplasia punctata, the concentration of phytanic acid was increased, whereas pristanic acid was within the control range, resulting in a low pristanic acid/phytanic acid ratio. In the blood spot from a patient with X-linked adrenoleukodystrophy, the concentrations of the acids and their ratio were normal. These findings are consistent with results for these acids in plasma from such patients. Measurement of phytanic acid and pristanic acid and their ratios in stored dried blood collected at neonatal screening can therefore be used in the diagnosis of peroxisomal disorders, especially for those cases in which, owing to early death of the patient, no other material is available for biochemical investigations.