Atypical presentations of propionic acidemia

Abstract

One of the most common recessively inherited organic acidemias is the Propionic Acidosis (PA) which results from Propionyle-CoA Carboxylase (PCC) enzyme deficiency that is necessary for the catabolism of the branched chain Amino Acids and other metabolites. Classically this disease presented with high anion gap metabolic acidosis with its clinical consequences. We report 4 patients who presented to our facility with sepsis like picture and no metabolic acidosis. All of them were found to have high ammonia level. Diagnosis was confirmed by tandem MS/MS and urine Gas Chromatography/ Mass Spectrometry (GC/MS). All of them were treated supportively and by supplementation of adequate calories and PA formula. The different presentations may be very well attributed to the PCC molecular defects heterogeneity. Mutations in both genes PCCA and PCCB can cause PA with more frequent heterogeneity of PCCA gene. In spite of the fact that PCCB gene is responsible for the most of the oriental cases, our first patient condition was attributed to PCCA gene with a rare mutation which was not described in the literatures.