Rhizomelic chondrodysplasia punctata is a rare, multisystem, developmental disorder characterized by the presence of stippled foci of calcification in hyaline cartilage, coronal vertebral clefting, dwarfing, joint contractures, congenital cataract, ichthyosis, and severe intellectual disability. The cataracts are present in about 72% of cases, and skin changes in about 27%. The coronal cleft of the vertebral bodies is demonstrable radiologically and appears to represent embryonic arrest with cartilage occupying the cleft between the anterior and posterior parts of the vertebral bodies. Biochemically, RCDP patients have subnormal levels of red cell plasmalogens and progressive accumulation of phytanic acid, which is normal at birth, but increases to levels more than 10 times by age of 1 year.
Most patients with rhizomelic chondrodysplasia punctata type 1 have mutations in the PEX7 gene, which encodes peroxin 7, the cytosolic PTS2-receptor protein involved in peroxisomal import of protein.