Prader-Willi Syndrome and its Linkage to Genetics - Essay Example

Diagnosis and Treatment of Prader-Willis Syndrome…….….…….9 7. Conclusion………………………………………………….………10 8. References……………………………………………..….………..12 Prader-Willi Syndrome and its Linkage to Genetics Prader-Willi Syndrome, moreover referred to as PWS, is a genetically linked disorder that afflicts various parts of the human anatomy. The disorder presents as hypotonia during infancy, coupled to delayed physical development, stunted growth, and difficulties in feeding.

The carrier begins to develop an unusually high appetite beginning in childhood, which results in hyperphagia or continuous over-eating, as well as overweight and obesity (Cassidy & Driscoll 2009). For individuals carrying the defective genes that cause PWS, especially those afflicted by obesity, a high prevalence of Diabetes Mellitus II exists. The genetic disorder was first characterized by Heinrich Willi and Andrea Prader before research by Guido Fanconi, Andrew Ziegler, and Alexis Labhart provided more information on the disorder.

Prader-Willi Syndrome, as a genetic disorder, involves alterations on chromosome 15(q11-13), whereby seven genes on this chromosome are deleted (Goldstone 2009). Alternatively, the 15q chromosome is not expressed because of a partial deletion on the paternally derived chromosomes. This disorder is prevalent in between 1 in 10,000 and 1 in 25,000 of the population. The origin of the defective genes from paternal chromosomes is especially important since the region of the chromosome involved is affected by imprinting from parent origin.

This means that only a single gene copy undergoes expression with the other corresponding gene being silenced via imprinting. For those genes that are affected in PWS, the gene that normally undergoes silencing or imprinting is the maternal copy with the expression of the paternal gene copy going ahead (Goldstone 2009). The result of this is that, the carrier only has one working copy of this gene and these PWS carriers possess one silenced copy and one copy that does not work. Prader-Willi Syndrome has a sister syndrome that is known as Angelman Syndrome, which involves maternally-derived genetic material at the same exact genetic location as PWS.

While Prader-Willi Syndrome is considered as a rare genetic disorder, it occurs commonly in a majority of genetic clinics, being obesity’s most common genetic cause as identified to date. Prader-Willi Syndrome is prevalent in people of all races, ethnic backgrounds, and gender (Cassidy & Driscoll 2009). Phenotypic Features Associated With the Disease The basis for most of the symptoms presenting in PWS may be due to the brain’s hypothalamic region’s dysfunction (Gelehrter 2008). The hypothalamic region of the fetus is vital during child labor and its deregulation may help to explain the high number of post-mature or pre-mature births for children later diagnosed with PWS.

Abnormal release of Luteinizing Hormone is thought to cause the decreased amount of sex hormones that result in testes not descending, small sized gonads, insufficient growth over puberty, and amenorrhea. Hypothalamic deregulation causes deficiency of growth hormone that contributes to reduced energy expenditure due to a deficit in lean body mass and excessive body fat. Disturbance of hypothalamus action also leads to daytime hyper-somnolence and aberrant body temperature control. Hyperphagia and insatiable hunger