Phytanoyl-CoA alpha-hydroxylase (PHYH) is also called Phytanoyl-CoA dioxygenase, peroxisomal, Phytanic acid oxidase and the gene names PHYH or PAHX. PAHX is involved in lipid metabolism and converts phytanoyl-CoA to 2-hydroxyphytanoyl-CoA. PAHX is expressed in liver, kidney, and T-cells. Defects in PHYH can cause Refsum disease (RD).