Research into detailed aspects of the phytanoyl-CoA dioxygenase containing 1 isoform a revealed its role in the alpha-oxidation of phytanoyl-CoA, a metabolite of phytanic acid. Phytanic acid is a long-chain fatty acid that requires alpha-oxidation, before entrance into the beta-oxidation pathway, due to a methyl group on the third carbon. Through evolutionary sequence analysis it was shown that PhyD is most conserved in animals and fungi most likely due to them requiring it to break down the fatty acids they consume, whilst high conservation was not required by plants. The defined active site was discovered to be inside a cleft, this cleft contains the binding sites for Fe(II) and 2-oxoglyterate binding site. This structure is very similar to phytanoyl-CoA hydroxylase indicating probable analogous functions. Compared to the other isoforms there is highest similarity between isoform a and c. Isoform b is most far removed due to a change in reading frame.
The investigation of the molecular mechanics of PhyD show that mutations to this gene can cause Refsum's disease (RD) due to the build up of phytanic acid, thus a greater knowledge of its action may play a vital role in treatment, recognition and prevention of this disorder. PhyD is highly expressed in tissues that are symptomatic in RD indicating a possible role in the disease state. Further research into the expression data of this gene may provide valuable information due to the hydroxylase and dioxygenase having varying tissue transcription, which may show that several different genes play a role in the complex symptoms of RD.