Prader-Willi+syndrome

= Prader-Willi Syndrome =

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1.) Who first discovered this disorder? Where, when and under what circumstances was it discovered?

Prader-Willi syndrome was first discovered by the Swiss doctors Andrea Prader, Alexis Labhart, and Heinrich Willi in 1956 in Zurich, Switzerland based on characteristics that they found in nine children that they had examined during their time as pediatricians at the Children’s Hospital in Zurich where they were studying children with the condition.

2.) What are the symptoms/characteristics associated with this disorder? At what age do the symptoms begin? Are the symptoms treatable? If so, how? Is the disorder fatal?

At birth, those with Prader-Willi syndrome generally exhibit poor muscle tone, (also known as hypotonia), poor feeding skills, small genitalia, and unique facial features. As they grow older, their metabolism slows down and developmental milestones are not reached at the same time as they would be in children without the condition, be those mental and physical. (For example, learning how to walk or talk.) An insatiable appetite is also developed, leading to suffers constantly feeling as if they will starve to death at any moment. Some symptoms such as hypotonia have been treated with experimental testosterone replacement therapy; yet even with this, the ability of the disorder to cause insatiable hunger often leads to obesity, type 2 diabetes, high blood pressure, high cholesterol, strokes, and even death; with death being caused by either eating themselves to death or poor management of the diet and poor treatment of the conditions listed above.



3.) What is the inheritance pattern of the disorder: dominant, recessive, sex-linked, autosomal, other?

The inheritance pattern of Prader-Willi syndrome typically autosomal recessive; (though in fewer than 10% of cases are more complicated than that,) and it is caused by the deletion of a part of the paternal copy of chromosome 15 or by maternal uniparental disomy.

4.) Are there any environmental factors that can affect the symptoms (either aggravate or alleviate)

Well, some environmental factors that can aggravate the condition are a poor diet that is high in sugar, fat, calories, etc along with a lack of exercise. One treatment that can alleviate some symptoms is the aforementioned experimental testosterone replacement therapy, which can improve motor functions and overall movement in a patient. Also strict diet control, even going as far as a feeding tube can help curb obesity and health problems in PWS sufferers can greatly improve quality of life.

5.) How common is the disorder? Does it occur more frequently in certain parts of the world or in certain ethnic groups or in one sex?

PWS, (Prader-Willi syndrome) happens in one out of 15,000 births, affects males and females equally, all races equally, all parts of the world equally, and it is the most common genetic disorder that causes deadly childhood obesity.





6.) What tests are done to confirm a diagnosis of this disorder?

The genetic disorder is identified through a blood test that can identify genetic abnormalities called methylation analysis. But to identify which specific type of PWS a person has, a myriad of different tests can be used; for example fluorescence in-situ hybridization or the FISH test is used to identify deletion of part of the parental copy of the chromosome specifically and can assist in treatment of a child by giving both doctors and parents an exact knowledge of what is wrong in their patient/child. While methylation analysis is used in 99% of cases and is universal, (being able to diagnose deletion, paternal deletion, or imprinting mutation,) in cases of imprinting mutation, other blood tests can be done on the parents to confirm the diagnosis, given the rarity of that cause of Prader-Willi syndrome.

7.) Which chromosome(s) is responsible for this disorder? Is it caused by a gene mutation? Which gene is involved? Is it caused by a chromosomal mutation? Which type: nondisjunction, deletion, inversion, etc.?

The 15th chromosome is responsible for the disorder and is caused by a lack of active genetic material on the chromosome. In 70% of cases the conditions are caused by parental deficiencies in that copy of the chromosome, (be that deletion, mutation, etc). In 30-25% of cases are caused by inheriting two copies of chromosome 15 from your mother. There is also a very small chance (1%-3%) that the parental copy of the gene is inactive, (also known as nondisjunction.) The change, be it either of the three affects the entire chromosome and leaves one section ravaged and unable to perform its normal function which leads to the side effects that are seen in the condition.



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