PHYH and ichthyosis: Refsum’s disease is a recessive disorder primarily caused by mutation of the gene for the peroxisomal enzyme phytanoyl-CoA hydroxylase (PHYH) and is clinically characterized by CA, peripheral polyneuropathy, sensorineural deafness, retinitis pigmentosa and anosmia with skeletal abnormalities, ichthyosis, renal failure, cardiomyopathy or arrhythmias.