Refsum's disease is due to deficiency of which of the following enzyme?: (A) Malonate dehydrogenase, (B) Thiophorase, (C) Succinate thiokinase, (D) Phytanic alpha oxidase
Answer is D. Phytanic alpha oxidase 

Refsum disease is caused by a deficiency of phytanic acid α -hydroxylase (α -oxidase) which is required for a-oxidation of methylated fatty acids, phytanic acid.