Jarcho-Levin syndrome is a rare genetic disorder characterized by distinctive malformations of bones of the spinal column (vertebrae) and the ribs, respiratory insufficiency, and/or other abnormalities. Infants born with Jarcho-Levin syndrome have short necks, limited neck motion due to abnormalities of the cervical vertebrae and short stature.
In most cases, infants with Jarcho-Levin syndrome experience respiratory insufficiency and are prone to repeated respiratory infections (pneumonia) that result in life-threatening complications. The vertebrae are fused and the ribs fail to develop properly, therefore, the chest cavity is too small to accommodate the growing lungs.
There are apparently two forms of Jarcho-Levin Syndrome that are inherited as autosomal recessive genetic traits and termed spondylocostal dysostosis type 1 (SCDO1) and spondylocostal dyostosis type 2 (SCDO2).
Jarcho-Levin Syndrome is characterized by multiple skeletal deformities caused by fused and/or malformed vertebrae, small, malformed or missing ribs, and a chest cavity that is to small for the infant’s lungs especially as the lungs grow. There is incomplete development (dysplasia) of one side of certain vertebrae (hemivertebrae), fusion of certain ribs, and/or other rib malformations. Consequently the infant is subject to repeated and severe infections of the lungs (pneumonia).
As a result of these developmental problems, the neck, trunk and torso appear to be short so that patients are considered to be of “short stature” or dwarfs. The fingers are usually webbed (syndactyly), elongated and permanently bent (camptodactyly).
In addition, symptoms may include a broad forehead, a wide nasal bridge, nostrils that are tipped forward (anteverted nares), upwardly slanted eyelids, and an enlarged posterior skull. Occasionally distention of the stomach and pelvis may occur due to an obstruction of the bladder. Undescended testicles, absent external genitalia, a double uterus, closed or absent anal and bladder openings, a single umbilical artery, and defects of the brain may also be present.
SCDO2 is milder than SCDO1 in that not all vertebrae are affected.
There are two forms of Jarcho-Levin syndrome that are transmitted as autosomal recessive genetic traits. SCDO1 is caused by an abnormality in the DLL3 gene located on chromosome 19 at 19q13. SCDO2 is caused by an abnormality in the MESP2 gene located on chromosome 15 at 15q26.1.
Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 19q13″ refers to band 13 on the long arm of chromosome 19. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.
All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
Jarcho-Levin Syndrome is a very rare disorder that affects males and females in equal numbers. There seems to be a higher incidence of this disorder in people with Spanish heritage.
Jarcho-Levin syndrome is diagnosed by the presence of abnormalities in the spine, back and chest that are present at birth. Diagnosis can sometimes be made prenatally by ultrasound examination.
Treatment of Jarcho-Levin syndrome is sympathetic and supportive. Genetic counseling may be of benefit for families of people with this disorder.
The Vertical Expandable Prosthetic Titanium Rib (VEPTR) was approved by the FDA in 2004 as a treatment for thoracic insufficiency syndrome (TIS) in pediatric patients. TIS is a congenital condition where severe deformities of the chest, spine, and ribs prevent normal breathing and lung development. The VEPTR is an implanted, expandable device that helps straighten the spine and separate ribs so that the lungs can grow and fill with enough air to breathe. The length of the device can be adjusted as the patient grows. The titanium rib was developed at the University of Texas Health Science Center in San Antonio. It is manufactured by Synthes Spine Co.. http://www.synthes.com/sites/NA/Products/Spine/Screw_Hook_Rod_and_Clamp_System/Pages/VEPTR_and_VEPTR_II.aspx
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