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I will be working on expanding the article on Jacobsen syndrome. I will be working with Amratha Chandrakumar. I will be the Primary Author of the project.

Italicized portions were directly copied from the original article stub. Included in this is the picture on the original article, seen below. All other work is original, including citations.

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'' Jacobsen Syndrome, also known as 11q deletion disorder, is a rare congenital disorder resulting from deletion of a terminal region of chromosome 11 that includes band 11q24.1. It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems including heart defects and a bleeding disorder. Jacobsen syndrome was first identified by Danish scientist Petra Jacobsen in 1973. ''

Genetics
Most cases of Jacobsen syndrome are not inherited. This syndrome occurs sporadically, during the formation of reproductive cells or during early fetal development, leading to a deletion of a chromosome. Those affected by this disease have no family history of this disease, but are able to pass this chromosomal deletion to their offspring. Approximately 10% of individuals with this disease inherit the abnormal chromosome from an unaffected parent.

Individuals are able to inherit this disorder from a parent that has a balanced chromosome translocation. The balanced translocation consists of a segment of chromosome 11 to exchange with another segment of a chromosome. Balanced translocations do not have any consequences, as the raw genetic material does not change. However, during reproduction, offspring can obtain an unbalanced translocation from their parents. The gain of an unbalanced translocation causes newborns to develop Jacobsen syndrome, resultant of lost genetic material from chromosome 11's long (q) arm terminal. Between 170 to 340 genes can be deleted on the end of the q arm of chromosome 11, and deletions can range anywhere from subband 11q23.3 to the telomere. A few cases have been noted to have a breakpoint at the FRA11B fragile site

Signs and Symptoms
Delayed development is the most common symptom seen in those with Jacobsen syndrome. Many are in the bottom 5% of the population in terms of height. Some opt to treat these issues with growth hormone injections, but this is uncommon and up to the individual parent. Various facial defects also exist. These include wider set eyes (trigonacephaly), folding of the skin near the subject's eyes, thin lips, a receding chin (retrognathia), as well as anteverted nostrils, to name a few. Most of these can be treated by plastic surgery to minimize their effects.

Other symptoms include changes to the central nervous system that affect normal brain and spinal cord functions. These can manifest itself in the form of lower IQ scores, various learning impairments and speech disorders. Another common result of altered central nervous system function is the impairment of simple motor skills, resulting in difficulty in walking, standing, or sitting down. Jacobsen syndrome patients also have a higher diagnosis rate of attention deficit-hyperactivity disorder

Diagnosis and Prognosis
Testing for Jacobsen syndrome is ordered primarily for infants that display signs of mental retardation and/or distorted facial features. Fluorescence In Situ Hybridization (FISH) can be used to determine the location and magnitude of deletion on chromosome 11. Traditional metaphase karyotyping can also be used to determine whether a deletion is present, but any detailed information must be determined by other cytogenetic methods.

Presently, no cure or therapy is available to replace the genes lost on the deleted segment of chromosome 11. Various treatments are available depending on the severity of the syndrome. Some individuals may need surgery to correct face and heart defects or abnormalities. Programs such as physical therapy, medical services and educational support are available for those with the syndrome. Management programs are available to help minimize health problems that can arise with the syndrome. Routine examinations with their family physicians are highly recommended. Genetic counselling is also available for those with the syndrome and support groups are recommended for both families and patients themselves. Individuals with Jacobsen syndrome have a 90% chance of having Paris-Trousseau syndrome, where individuals have abnormal bleeding and bruise much more easily.

Epidemiology
Jacobsen syndrome affects 1 in every 100,000 newborns. Approximately 25% of all affected children succumb before reaching their 24th month, primarily due to an increase in cardiac incident rates. Children that survive past this 24-month threshold are usually healthy. There are approximately 250 confirmed cases in the world, with females having a 70% higher chance of contracting the disease than males. The approximate lifespan of individuals with this disease is unknown, but many individuals reach adulthood.