Monday, June 8, 2009

rs2200733 ok, now what?

I am busy pouring through all sorts of association studies which I had let sort of slip through my fingers. I have been cue'ing a lot of these and only in the last few days have been able to get to them. Most of the SNP that the press put out there now seems to be dying off pretty nicely.

Although there are bits of useful data out there, most is just noise......but one of the SNPs which caught my eye was rs2200733 studied in Icelandic, Italian and other Caucasian populations with a small replication in an Asian population as well......What does rs2200733 predispose to?

Atrial Fibrillation. A condition that can lead to unannounced strokes, syncope, and heart failure (at times)
Atrial fibrillation is the most common arrhythmia in the United States.

About 2.3 million
Americans have atrial fibrillation (Go, 2002). Men have a 50% higher incidence than women at any age (Benjamin, 1994). Among individuals 50 years of age and older, the prevalence is higher for Caucasian individuals than African Americans.

The prevalence
of atrial fibrillation is 0.1% for individuals under age 55 and 9.0% for individuals over the age of 80 (Go, 2002). HT CPMC.....

Here's why I am revisiting it? It popped up on my screen as a SNP with a study which purported an Odds Ratio greater than 2......
In my mind, no SNP should be even looked at without having this.....why?

Well, most clinical scenarios have

1. Good risk prediction tools already, as with the 9p21.3 issue
2. No true benefit of presymptomatic detection, i.e. no effective prevention (Parkinson's)

3. No ability to guide therapeutic decision making..... This is true in 99% of cases, aside from pharmacogenomics that is.......

So why am I looking again at rs2200733? Because this may actually be a case where I think it may augment my other clinical tools of prediction......Maybe.

Why only maybe?

A. Most of my patients get annual physicals with annual EKGs.....and often AFIB manifests with symptoms....

B. Most of the patients with AFIB are elderly and in the studies some indicate earlier AFIB pops, some don't which may be confounding in the study

C. Most of the people with AFIB that I see report a family history of some sort of arrythmia, most often AFIB.....

That being said, there is a population <10% who end up with No family history, Present Early and present with a stroke....It is rare, but does I naturally would want to watch that population more than not......But does that mean I should do "More" for them?

In the age of Comparative Effectiveness, I may not be allowed to..........There is no ICD9 code for genetic predisposition to Atrial Fibrillation......

But maybe people would pay more than the 20 dollar copay for care???? Probably not that often, but maybe.....And for what?
A home monitor to be hooked up on them 24/7?

It turns out

DeCode sells a test with this SNP, Is on the Affy and Illumina Chips, I.E avail for 23andM- and Navi.............

None of these are actually valid clinical tests yet though.....Similar to other "clinical" detection tools we have today.

So what I am going through is in essence mental acrobatics while I await a company to do a study which proves that there is some benefit and some action to be taken here.......

The Sherpa Says: While a promising SNP is out there, it is just that a promising SNP. Most of these things won't affect me clinically for another 5 years. I wonder what the public will do with this data? Will they go see a doctor? Who ultimately would be asking the same question I am.....and waiting for the same data

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