This is a rare inherited condition that affects how the cartilage and the bones form. Also known as asphyxiating thoracic dysplasia, this syndrome is evident at the birth of the infant and mainly involves the pelvis, limbs and the rib cage. As these infants have a small chest, it can restrict the growth of the lungs that can cause life-threatening breathing problems. This condition is estimated to affect around 1 in 100,000 to 130,000 live births.
Causes
This can develop as the result of the genetic mutation in the IFT80 or DYNC2H1 genes which accounts for most of the cases. These genes are responsible for the production of proteins that are necessary for the process known as intraflagellar transport (IFT) that carry materials from and to the tips of cilia which are the cell structures. The cilia are important for the various chemical signaling pathways such as the sonic hedgehog pathway that are required for the growth, division and the maturation of the cells. The genetic mutation affects the IFT transport that disrupts the normal function or the assembly of the cilia. Research indicates that when these signaling pathways are affected, it can cause the abnormalities of the bone growth. This syndrome is inherited in an autosomal recessive pattern meaning both the copies of the gene in each cell are defective.
Symptoms
This syndrome primarily affects the bones of the individual. They are often born with skeletal abnormalities such as extra fingers, abnormally shaped pelvis, small narrow chest, short ribs and shortened bones of the limbs. The chest abnormalities can cause life-threatening breathing difficulties among the infants who mostly do not survive past their infancy. In addition, they may also develop kidney and liver problems, high blood pressure, dental abnormalities and an eye condition called retinal dystrophy that can cause vision loss.
Diagnosis
The diagnosis of this condition is based on the clinical evaluation of the individual’s medical history, family history and in the identification of the features characteristic of this condition. The severity of the syndrome appears to vary among the affected cases with some exhibiting life-threatening breathing difficulties and others presenting the absence of any distress. The prenatal diagnosis of this syndrome is possible with the ultrasound imaging that can identify the shortened limb development. After the birth, the abnormalities of the skeletal system can be identified with the X-ray findings. In some of the families, the genetic testing can confirm the diagnosis.
Treatment
The treatment is based on the severity of the symptoms among the affected individuals. If the severe breathing difficulty is evident after the birth, the mechanical ventilation or the surgical intervention may be necessary for the reconstruction of the chest. In other cases, the respiratory infections should be monitored and managed to prevent the respiratory failure. Those exhibiting kidney problems may require dialysis or renal transplantation.
References
https://rarediseases.info.nih.gov/diseases/3049/jeune-syndrome
https://ghr.nlm.nih.gov/condition/asphyxiating-thoracic-dystrophy#statistics
http://www.seattlechildrens.org/medical-conditions/chromosomal-genetic-conditions/jeune-syndrome/
