Diseases & Conditions
The osteochondrodysplasias are a group of rare disorders of bone or cartilage that cause the skeleton to develop abnormally.
In osteochondrodysplasias, the growth plate, which contains cartilage, does not make new bone cells. Thus, growth of bone is impaired.
Each type of osteochondrodysplasia causes different symptoms. Osteochondrodysplasias usually cause short stature (dwarfism). Some cause more shortening of the limbs than the trunk (short-limbed dwarfism), whereas others cause more shortening of the trunk than the limbs. Some children and adults have short limbs, bowlegs, a bulky forehead, an unusually shaped nose (saddle nose), and an arched back. Sometimes, joints do not develop their full range of motion.
A doctor usually makes the diagnosis based on the symptoms, physical examination, and x-ray studies of the bones. Sometimes the abnormal genes responsible for osteochondrodysplasias can be detected, usually by a blood test. Analyzing the genes is most helpful for predicting the disease before birth. Diagnosis of severe types before birth is also possible using other methods. In some cases, the fetus can be directly viewed with a flexible scope (fetoscopy), or an ultrasound is performed. Surgery may be needed to replace joints that have severely restricted movement with artificial joints.
Because the inheritance pattern in most types is known, genetic counseling can be effective. Organizations such as Little People of America ( www.lpaonline.org ) provide resources for affected people and act as advocates on their behalf. Similar societies are active in other countries.
Last full review/revision February 2008 by Frank Pessler, MD, PhD; David D. Sherry, MD
Source: The Merck Manual Home Edition