Table I.
PEX mutations associated with the ZSS disorders
| Mutation | Frequency of PEX gene defects in ZSS disorders | Function |
| % | ||
| PEX1 | 58 | Peroxisome biogenesis and PTS receptor recycling to the cytosol |
| PEX2 | 4 | E3 ligase; PTS receptor ubiquitination |
| PEX3 | <1 | PMP biogenesis and Pex19 receptor |
| PEX5 | 2 | PTS1 receptor for peroxisomal matrix protein import |
| PEX6 | 16 | Peroxisome biogenesis and PTS receptor recycling to the cytosol |
| PEX10 | 3 | E3 ligase; PTS receptor ubiquitination |
| PEX12 | 9 | E3 ligase; PTS receptor ubiquitination |
| PEX13 | 1 | Peroxisomal matrix protein import |
| PEX14 | <1 | Component of translocon for peroxisomal matrix protein import |
| PEX16 | 1 | PMP biogenesis |
| PEX19 | <1 | PMP biogenesis; budding of pre-peroxisomal vesicles from the ER |
| PEX26 | 3 | Peroxisomal membrane receptor for Pex6 |
ZSS, a main subgroup of PBDs, is comprised of the following diseases: Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum disease. Mutations in the PEX7 gene are responsible for the second PBD subgroup, called rhizomelic chondrodysplasia punctata type I. This analysis is reproduced here from Ebberink et al. (2010), with some modifications, with permission from John Wiley & Sons, Inc.