Contributor: Gordon K. Klintworth
The peroxisome biogenesis disorders are a group of heterogeneous autosomal recessive, lethal conditions characterized by multiple defects in peroxisome function. The peroxisomal disorders include Refsum disease, Zellweger syndrome, Conradi syndrome, neonatatal adrenoleukodystrophy [adrenoleukodystrophy - neonatal], and rhizomelic form of chondrodysplasia punctata [chondrodysplasia punctata - rhizomelic type ]. The altered metabolism resulting from the defects in peroxisome function result in ectodermal and mesodermal malformations. At least 11 complementation groups are associated with peroxisome biogenesis disorders. These conditions result from a deficiency or reduced activity of different peroxisomal enzymes some enzymes, such as dihydroxyacetonephosphate acetyltransferase, phytanic acid oxidase, alkyldihydroxyacetonephosphate synthetase, or an inability to import peroxisomal thiolase The concerted action of peroxins is encoded by  PEX  genes. They are required for import of matrix proteins into peroxisomes. At least 15 PEX genes have been identified in yeast and the human orthologues. PEX7 encodes the peroxisome targeting signal 2 (PTS2) receptor. A mutation in the PEX7 gene causes rhizomelic chondrodysplasia punctata. All rhizomelic chondrodysplasia punctata patients from CG11 with detectable PEX7 were found to contain mutations in PEX7.  Peroxisome biogenesis disorder 11 is linked to classic rhizomelic chondrodysplasia punctata.