Four patients with COMP mutations exhibited typical pseudoachondroplasia (PSACH) (MIM #177170) with severe short-limb dwarfism, joint pain and stiffness, and early-onset osteoarthritis, and 4 patients with mutations in FBN1 represented as acromelic dysplasia (MIM # 102370) shared severe short stature, short hands and feet, and joint limitations. Here, COMP is linked to pseudoachondroplasia.