Abnormal circulating long-chain fatty-acid concentration Elevated circulating pristanic acid concentration following branched-chain fatty acid ingestion 2024-07-21T13:51:10Z Concentration of pristanic acid in the blood circulation above the upper limit of normal. This finding can be observed in Zellweger syndrome. Note that branched-chain fatty acid accumulation depends on dietary intake of phytanic acid, which is minimal in formula- and breast-fed infants. Thus, phytanic and pristanic acid levels are normal in a neonate with Zellweger spectrum disorder.