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Posted on May 6, 2008 at 11:59 PM

Today’s Science Times included an interesting story about work toward classifying diseases by their genetic underpinnings. There are bunch of interesting angles to this idea, but one in particular stood out for me: as we gain greater insight into the nature of disease, our concept of what it means to be “sick” changes. From Andrew Pollack’s piece:

The shift from symptoms to anatomical measurements had big implications for patients, said Dr. Duffin, who is also a hematologist.

Up until the 18th century, you had to feel sick to be sick, she said. But now people can be considered sick based on measurements like high blood pressure without feeling ill at all.

Indeed, Dr. Duffin said, people who feel sick nowadays dont get to have a disease unless the doctor can find something and instead might be told that its all in their head. Doctors argue, for instance, about whether fibromyalgia or chronic fatigue syndrome, which have no obvious anatomical causes, are really diseases.

Genes might allow the study of diseases at a finer level than even physiological tests. Genes are the instructions for the production of proteins, which interact in complex ways to carry out functions in the body. Disruptions in these molecular pathways can cause disease.

It gives you a direct connection to what the root causes are, said Dr. David Altshuler, a professor of medicine and genetics at Harvard and Massachusetts General Hospital, and a researcher at the Broad Institute. That is different from listening to a stethoscope.

So we’re moving from the concept of disease as a state of impaired function to it representing particular sets of probabilities. In the past you were sick when you had a heart attack. Today, you’re sick — or pre-sick, perhaps — when you have high cholesterol. What about when it’s possible to identify constellations of genes that significantly increase your chances of having high cholesterol, or a heart attack. Would that be considered a disease? Would you be pre-diseased? Potentially-diseased? Simply at risk?

People are already struggling with these questions. From a segment later on in Pollack’s piece:

She and others said genetic classification could bring its own ambiguities. Newborns are now often screened for cystic fibrosis with the idea that they can be treated early to help avoid complications. But some infants with a mutation in the gene responsible for the disease are unlikely ever to have symptoms. Do they have the disease?

We dont know what to call these infants, said Dr. Frank J. Accurso, a professor of pediatrics at the University of Colorado. We dont even have a good language for it yet.

One other interesting tidbit from the story: the aggregate of the connections between genes and disease is known as the “diseasome.”

-Greg Dahlmann

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