Peroxisome Biogenesis Disorder 9b, also known as refsum disease, adult, 2, is related to peroxisome biogenesis disorder 14b and rhizomelic chondrodysplasia punctata, type 1. An important gene associated with Peroxisome Biogenesis Disorder 9b is PEX7 (Peroxisomal Biogenesis Factor 7). Affiliated tissues include brain and heart, and related phenotypes are sensorineural hearing impairment and reduced visual acuity