Asphyxiating thoracic dystrophy

Asphyxiating thoracic dystrophy, also known as Jeune syndrome, is an inherited disorder of bone growth characterized by a small chest, short ribs, and shortened bones in the arms and legs. Additional skeletal abnormalities can include unusually shaped pelvic bones and extra fingers and/or toes (polydactyly). Infants with this condition are born with an extremely narrow, bell-shaped chest that can restrict the growth and expansion of the lungs. Life-threatening problems with breathing often result, and most people with asphyxiating thoracic dystrophy live only into infancy or early childhood.

Some people with asphyxiating thoracic dystrophy experience only mild breathing difficulties, such as rapid breathing or shortness of breath. These individuals may live into adolescence or adulthood. After infancy, people with this condition often develop life-threatening kidney (renal) abnormalities that cause the kidneys to malfunction or fail. Heart defects and a narrowing of the airway (subglottic stenosis) are also possible. Other, less common features of asphyxiating thoracic dystrophy include liver disease, pancreatic cysts, dental abnormalities, and an eye disease called retinal dystrophy that can lead to vision loss.

Asphyxiating thoracic dystrophy has an estimated incidence of 1 in 100,000 to 130,000 people.

Mutations in the IFT80 gene have been found in several families with asphyxiating thoracic dystrophy. The IFT80 gene provides instructions for making a protein that is found in cell structures called cilia. Cilia are microscopic, finger-like projections that stick out from the surface of cells. They are involved in cell movement and many different chemical signaling pathways. Cilia also play an important role in the perception of sensory input (such as sight, hearing, and smell). Although mutations in the IFT80 gene disrupt the normal development and maintenance of cilia, it is unclear how these mutations lead to skeletal abnormalities, kidney problems, and the other features of asphyxiating thoracic dystrophy.

In many cases, the cause of asphyxiating thoracic dystrophy is unknown. Mutations in an unidentified gene on chromosome 15 may account for the condition in some families. Researchers are working to locate other genes that also may be associated with this condition.

Read more about the IFT80 gene.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.