Odd-numbered long-chain fatty acids in propionic acidaemia

In patients with propionic acidaemia (PA), the increased intracellular conc entration of propionyl-CoA leads to a relative abundance of odd-numbered lo ng-chain fatty acids (OLCFAs) in body lipids. We investigated the relative amount of OLCFA in erythrocyte membrane lipids over a period of 1-8 years i n five patients with early onset PA and present their clinical outcome. Aft er extraction from erythrocyte membrane lipids and esterification, fatty ac ids were analysed by capillary column gas chromatography. The sum of the OL CFA 15- and 17- carbon saturated and 17-carbon monounsaturated fatty acids (C15:0, C17:0, C17:1) was calculated and expressed as a percentage of the t otal C14-C22 fatty acids in the sample. Three patients (pccBC-complementati on group) presented with a stable clinical course and showed OLCFA values u sually below 1.9% (median % +/- SD: 1.4 +/- 0.5, 1.6 +/- 0.5, 1.8 +/- 0.5). Two patients (pccA-complementation group) had a more severe course of the disease and showed higher medians and a broader range of OLCFA levels (2.2 +/- 1.2 and 2.2 +/- 0.8). Conclusion Our study shows that odd-numbered long-chain fatty acid concentr ations are increased in patients with propionic acidaemia and are higher in those with a more severe clinical course. The value of odd-numbered long-c hain fatty acids in the assessment of the phenotypic severity and in the ma nagement of propionic acidaemia remains to be proven in a prospective long- term study with more patients of differing phenotype.