HSD17B4 and rhizomelic chondrodysplasia punctata: 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.