| |
Prader-Willi syndrome
Prader-Willi syndrome (PWS) is an uncommon
inherited disorder characterized by mental retardation, decreased
muscle tone, short stature, emotional lability and an insatiable
appetite which can lead to life-threatening obesity. The syndrome
was first described in 1956 by Drs. Prader, Labhart, and Willi.
I've seen countless SEO companies brag about such things on the home pages of their websites. But here's what the shady seo company with the bold promises would do. A business may do this on their own but many will want to consult with a professional SEO company to handle the management of web traffic and the visibility of your business.
© Copyright 2005-2010 Department of Pediatric. All rights reserved.
A template of the Vooweb.com Website templates network
|
|
PWS is caused by the absence of segment
11-13 on the long arm of the paternally derived chromosome
15. In 70-80% of PWS cases, the region is missing due to a
deletion. Certain genes in this region are normally suppressed
on the maternal chromosome, so, for normal development to
occur, they must be expressed on the paternal chromosome.
When these paternally derived genes are absent or disrupted,
the PWS phenotype results. When this same segment is missing
from the maternally derived chromosome 15, a completely different
disease, Angelman syndrome, arises. This pattern of inheritance
when expression of a gene depends on whether it is inherited
from the mother or the father is called genomic imprinting.
The mechanism of imprinting is uncertain, but, it may involve
DNA methylation.
Genes found in the PWS chromosomal region
code for the small ribonucleoprotein N (SNRPN). SNRPN is involved
in mRNA processing, an intermediate step between DNA transcripton
and protein formation. A mouse model of PWS has been developed
with a large deletion which includes the SNRPN region and
the PWS 'imprinting centre' (IC) and shows a phenotype similar
to infants with PWS. These and other molecular biology techniques
may lead to a better understanding of PWS and the mechanisms
of genomic imprinting.
|
|
