Metatropic Dysplasia/Kniest Dysplasia

People with Metatropic Dysplasia/Kniest Dysplasia are born with a short trunk and shortened arms and legs. Kniest dysplasia is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. Type II collagen is essential for the normal development of bones and other connective tissues that form the body’s supportive framework. Most changes in the COL2A1 gene that cause Kniest dysplasia interfere with the assembly of type II collagen molecules. Abnormal collagen prevents bones and other connective tissues from developing properly, which leads to the signs and symptoms of Kniest dysplasia. This a rare condition and the exact incidence is unknown.