Spondyloepiphyseal dysplasia (SED) congenita is a disorder of bone development that causes short stature with a particularly short torso and short arms and legs. The parts of the body are not proportional to one another (disproportionate short stature) in people with this condition. Affected individuals typically have hands and feet that are of average size. SED congenita affects the bones of the spine (spondylo-) and the ends (epiphyses) of the long bones in the arms and legs. People with this condition also have problems with vision and hearing. The word "congenita" indicates that the condition is often noticeable at birth. The signs and symptoms of SED congenita can vary among affected individuals.

SED congenita is caused by variants (also called mutations) in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. This type of collagen is found in the clear gel that fills the eyeball (the vitreous) and in cartilage. Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development; most cartilage is later converted to bone. Type II collagen is essential for the normal growth and development of bones and other connective tissues.

Though it is one of the more common skeletal dysplasias, SED congenita is rare. The exact prevalence is unknown.

Typically, SED congenita is inherited in an autosomal dominant pattern, which means one copy of the altered COL2A1 gene in each cell is sufficient to cause the disorder. Many cases of this condition are the result of a new (de novo) variant in the COL2A1 gene that occurs during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These affected individuals have no history of the disorder in their family.

Published Date: December 19, 2024
Published By: National Institutes of Health