PEX5 and rhizomelic chondrodysplasia punctata type 2: Thus, we next investigated primary human fibroblasts from a patient with RCDP-2 (rhizomelic chondrodysplasia punctata type-2) harboring mutations in the enzyme glyceronephosphate O-acyltransferase (GNPAT) required for ether phospholipid synthesis via a PTS1/Pex5-dependent mechanism.