Scientists identify genetic basis of common diseases

i-696280e2138fb34dffe0074105c38eb4-6-13-07 snps.gif A consortium of UK researchers has identified genetic markers associated with common diseases like diabetes and coronary disease. The researchers identified small variations in the human genome that appear to be associated with a predisposition to certain diseases.

According to the authors, who published in the June issue of Nature, this research is important because the identification of variants, genes and pathways involved in particular diseases offers a potential route to new therapies, improved diagnosis and better disease prevention.

What they did:
The scientists extracted DNA from blood samples of approximately 2,000 individuals for each of 7 major diseases. Another approximately 3,000 samples were used as shared controls. They used single nucleotide polymorphism (SNP) microarrays to identify SNPs that were common to people with a particular disease.

SNPs are single letter changes in a person's DNA. They have been described as "endogenous mutagens" and can affect how humans develop disease. They can therefore serve as genetic markers for disease predisposition.

What they found:
The study identified 24 genetic markers across the following diseases:
1 in bipolar disorder,
1 in coronary artery disease,
9 in Crohn's disease,
3 in rheumatoid arthritis,
7 in type 1 diabetes and
3 in type 2 diabetes.

They also identified a large number of additional signals across these diseases that they believe are likely to yield more susceptibility loci.

I spoke with Scott Devine Ph.D., a researcher at Emory University who works on transposable genetic elements such as SNPs, about the importance of this research, its potential abuse by insurance companies and implications for the public.

Is there potential for insurance companies to discriminate against or charge higher rates for people carrying disease-associated genetic markers?

"The researchers," Dr. Devine explains, "do find markers that are associated with diseases, but these are not 100% penetrant diseases (there are other factors that help to dictate whether you get the disease). Insurance companies might want to look at these markers, but they could not tell for sure that you WILL get the disease. Either way, there is now genetic discrimination legislation underway that would not allow insurance companies to use this information."

Overall message:
Genetic analysis of human DNA to find disease-associated genetic markers is important because it may lead to the identification of pathways involved in particular diseases and therefore more improved therapies. We will no doubt be seeing more studies like this in the future.

Even if a person carries disease-associated genetic markers there are usually other factors (such as environment and lifestyle) that determine whether that person will develop the disease. Fortunately for us (the public) it is unlikely that insurance companies in the future will be able to use the presence of disease-associated genetic markers to discriminate against someone or charge higher fees for care.

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"Fortunately for us (the public) it is unlikely that insurance companies in the future will be able to use the presence of disease-associated genetic markers to discriminate against someone or charge higher fees for care."

What makes you think this ?
If I were an evil Insurance company CEO I would make sure that the results of such studies were incorporated into the small print of my company's policies. The idea that one could avoid paying out to those members of the population with a genetic predisposition to a particular disease would result in huge rises in profitability for health insurance companies (imagine if they didn't have to pay out for a lot of chronic problems like heart disease and diabetes).
I believe we are half way through a ten year moratorium on using the results of genetic tests to deny insurance but when that ends it will be a free for all for insurance companies to start withholding payments. It won't be a huge problem in europe where social medicine will pick up the bill but for those in the US who need private insurance there is a rather nasty shock not too far down the road.
Don't be too complacent about this one. Insurance companies are NOT charities. They make their money through avoiding paying out whenever they can avoid it and they would be irresponsible to their shareholders not to take full advantage of this potential goldmine.

Hi Martin C

Thanks for the comment. I think you're justified in maintaining a hint of skepticism.

Legislators may have good intentions of protecting the public from insurance company abuse of genetic information but while genetic discrimination legislation is indeed underway it still has a long way to go before becoming law.

According to the National Human Genome Research Institute of the NIH, the Genetic Information Nondiscrimination Act (GINA) of 2007 was passed in the U.S. House of Representatives however the Senate bill has yet to be voted on.

It'll be interesting to see how this all plays out in the future.