(more than 90 percent of narcolepsy patients were shown to carry one such variant, in * Phil's post May 3, *
http://www.eurekalert.org/pub_releases/2009-05/sumc-nia042809.php
"4,000 individuals, all of whom had the HLA variants that predispose to narcolepsy-cataplexy but only about half of whom had the disorder"), and the size and significance of the group of the study:
"During this study, the researchers ran whole-genome scans — which allow for the analysis of hundreds of thousands of genetic variations — of 1,800 people carrying the same HLA gene variant. Of the group, 800 had narcolepsy, and the goal was to find what differentiated these people from control subjects. The team found that a specific variation of a gene belonging to T cells — specialized immune cells that play a role in all immune responses — was present in narcolepsy."
~~ This vastly improves an easy non-invasive test that can contribute to dx, now that Mignot has brought it into focus. HLA blood testing might already be done differently based on new data and research precedent.
~~ If changes to our genes during our life bring the HLA "weakness, or shortness" to this point; symptoms and measurable criteria for dx would be progressively extreme as we age; (which explains, the most extreme symptoms later in life)
~~ "scientists may be able to identify people who are predisposed to narcolepsy and block specific gene variants in that person to stop the development of the disease."
The concepts "predisposed" and "development of the disease" are incredibly hopeful! Not randomly doomed from birth ...
BBC NEWS / HEALTH
00:05 GMT, Monday, 4 May 2009 01:05 UK
http://news.bbc.co.uk/2/low/health/8025662.stm
"Dr Mignot said: "Narcolepsy is probably the result of a series of unfortunate events, starting with genetic predisposition, involvement of an environmental trigger such as an infection, then T-cell activation, then effects on many other arms of the immune system."
He said the latest study raised the possibility of developing a therapy for narcolepsy which worked by blocking activity of the specific T-cell receptors."
~~ Best of all, the TCRA:
"The researchers discovered that in addition to unique HLA variants, people with narcolepsy-cataplexy are also more likely to have unique variants of the TCRA gene, which encodes a receptor protein on the surface of T cells.
"It is important to note that this study, like most genome-wide association studies, did not identify genetic variants that directly cause narcolepsy-cataplexy. Instead it identifies groups that are more likely to show narcolepsy-cataplexy and groups that are less likely to show the disorder.
In people with the HLA variants that predispose to narcolepsy-cataplexy, there is about a 20-fold higher frequency of the disorder if variants in the TCRA gene are present.
It is yet to be known which people with the genetic variants will go on to develop narcolepsy-cataplexy."
Twenty times the frequency should make this the gold standard diagnostic criteria.
Thanks, Phil and Steve. You have been genuine messengers of HOPE.