So far this list contains single enzyme deficiencies like Refsum disease (PHYH deficiency), racemase, MFP2 and SCPx deficiency, as well as biogenesis disorders such as Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease and rhizomelic chondrodysplasia punctata. This evidence concerns the gene SCP2 and phytanoyl-CoA hydroxylase deficiency.