Finding genetic links to disease still tough

Will advances in genetic understanding constrain or enhance human freedom? While interesting in theory, as a practical matter the genetic links to many diseases remain as puzzling as ever. The prevailing clinical methodology, which compares the genetic makeup of patients with healthy people, amounts to little more than "recreational genomics," according to one geneticist, because the variations found explain very little about the genetic links to most diseases.

New York Times:

Unlike the rare diseases caused by a change affecting only one gene, common diseases like cancer and diabetes are caused by a set of several genetic variations in each person. Since these common diseases generally strike later in life, after people have had children, the theory has been that natural selection is powerless to weed them out.

The problem addressed in the commentaries is that these diseases were expected to be promoted by genetic variations that are common in the population. More than 100 genomewide association studies, often involving thousands of patients in several countries, have now been completed for many diseases, and some common variants have been found. But in almost all cases they carry only a modest risk for the disease. Most of the genetic link to disease remains unexplained.