Chondrodysplasias is a name given to a group of diseases that affect the cartilage tissue and can cause problems with the skeleton, skin, eyes and mental function. These diseases are usually inherited and are caused by mutations of the gene for collagen II which is the main collagenous component of the cartilage. The severity of chondrodysplasias varies depending on the type of mutation. Osteoarthritis is nearly always present in patients with chondrodysplasias. Stem cell therapy is now looking promising as a treatment for chondrodysplasias.