Zellweger syndrome (Orphanet_912) (ZS) is the most severe variant seen in the peroxisome biogenesis disorders, Zellweger syndrome spectrum (PBD-ZSS; see this term), characterized by neuronal migration defects in the brain, dysmorphic craniofacial features, profound hypotonia, neonatal seizures, and liver dysfunction. Also known as: Cerebrohepatorenal syndrome, ZS.