interesting article from Science News

Re: interesting article from Science News

Erling — Wed, 02 Nov 2011 08:40:12 +0000

<[www.afibbers.org];

(note the date:)

Author: Jackie (---.clvdoh.adelphia.net)
Date: 08-05-06 05:25

Here's a review of a finding about the Connexin 40 Gene

Mutations in the Connexin 40 Gene, GJA5, Predisposes Patients to Idiopathic Atrial Fibrillation

July 3, 2006

By Sahar Bedrood B.S. and Asher Kimchi M.D.

Ottawa, Canada-

Atrial Fibrillation is the most common type of cardiac arrhythmia characterized by erratic electrical activation of the atrial myocardium, resulting in loss of effective contractility and an increase in clot formation. Michael H. Gollob et al from the University of Ottawa Heart Institute studied the genetic basis of atrial fibrillation as it relates to mutations in the connexin 40 gene, GJA5. Their results, published in the June 22, 2006 issue of The New England Journal of Medicine, found that mutations in GJA5 may predispose patients to idiopathic atrial fibrillation by impairing gap-junction assembly or electrical coupling.

The study focused on the GJA5 gene, which encodes connexin 40, a gap-junction protein with gene _expression restricted principally to atrial tissue in humans. Connexin 40 is thought to play a role in mediating atrial conduction through electrical coupling between cells. The study obtained archival tissue specimens from 15 patients with idiopathic atrial fibrillation. The GJA5 gene from genomic DNA from these cardiac tissues was sequenced. Identified GJA5 mutations were transfected into a gap-junction-deficient cell line to assess their effects on protein transport and intercellular electrical coupling.

In 4 of 15 patients, four heterozygous missense mutations were identified. In three patients, the mutations were found in the cardiac-tissue specimens, but not in the lymphocytes, indicating a somatic mutation rather than a germ line mutation. In the fourth patient, the sequence variant was detected in both cardiac tissue and lymphocytes, suggesting a germ-line origin. The mutations were in the highly conserved regions of the transmembrane spanning domains of connexin 40 protein. Confocal microscopic analysis of cells expressing mutant proteins revealed impaired intracellular transport or reduced intercellular electrical coupling.

It can be concluded from this study that mutations in GJA5 may predispose patients to idiopathic atrial fibrillation by impairing gap-junction assembly or electrical coupling.

Co-authors: Michael H. Gollob, M.D., Douglas L. Jones, Ph.D., Andrew D. Krahn, M.D., Lynne Danis, M.L.T., Xiang-Qun Gong, Ph.D., Qing Shao, Ph.D., Xiaoqin Liu, M.D., John P. Veinot, M.D., Anthony S.L. Tang, M.D., Alexandre F.R. Stewart, Ph.D., Frederique Tesson, Ph.D., George J. Klein, M.D., Raymond Yee, M.D., Allan C. Skanes, M.D., Gerard M. Guiraudon, M.D., Lisa Ebihara, M.D., Ph.D., and Donglin Bai, Ph.D.

[www.cardiologyonline.com]

Re: interesting article from Science News

Elizabeth H. — Tue, 01 Nov 2011 20:31:37 +0000

I have always thought AF was gentic, my mother and a couple of my aunts, (on my mothers side), had AF.

I have never bought the sodium/potassium ratio as the cause, I would say it is helpful, if you have AF, and magnesium as well. Many, many people have lousy diets and probably don't have adequate mag. or a Na/k ratio and do not have AF. Now they probably have high BP but not AF. I know a few people with high blood pressure, they do not have AF.

Liz

Re: interesting article from Science News

GeorgeN — Tue, 01 Nov 2011 09:01:15 +0000

Peggy,

Another quote from the article:

""Everyone thinks atrial fibrillation is idiopathic, and actually this is showing it can have a genetic basis," says Sarah Tabrizi, a neuropathologist at University College London. Like Gollob, she's intrigued by somatic mutations and identified one a few years ago in an Alzheimer's patient. The big challenge, she says, is getting access to patient tissue."

I think they mean idiopathic in the sense that there are not known genetic causes, as opposed to known associations such as CVD or high BP.

George

interesting article from Science News

PeggyM — Tue, 01 Nov 2011 05:45:19 +0000

[news.sciencemag.org]

For several days now i have been browsing thru the genetics archives of Science News. These are short, usually one page articles. Very interesting articles, some of which seem very pertinent to afibbers. This one surprised me by mentioning afib specifically. A quote:

"A heart condition called atrial fibrillation, which triggers heart rhythm problems and strokes, affects 10% of people 65 and older. But nearly all those cases are idiopathic, their cause unknown."

Does this mean that lone afib is actually much more common than we have been given to understand? Or am i misconstruing this article? Hans, can you address this at all?

Another quote:"The team focused on a particular gene, called GJA5, which produces a protein that helps control electrical conduction in the heart. Animals without the protein, connexin 40, develop atrial fibrillation, but mutations in the gene haven't previously been linked to the disease."

PeggyM