PEX5 and peroxisome biogenesis disorder: In contrast to other peroxisomal biogenesis disorder (PBD) mouse models (such as the Pex5, Pex2, Pex13 knockout mice), which mimic the Zellweger spectrum symptoms [53,54,55], the Pex11a knockout mice still contain peroxisomes that harbor the typical peroxisomal marker enzymes [40].