PEX1 and Zellweger syndrome: Only 50 missense mutations (29.4%, PEX1 = 21/85, PEX6 = 27/76, PEX26 = 2/9) were reported to be associated with Zellweger syndrome, which has a severe early-lethal clinical presentation (Additional file 5: Table S3), while the remaining 70.6% of variants are truncating stop or frameshift defects.