It Takes a Genome: How a Clash Between Our Genes and Modern Life Is Making Us Sick

Faint Genetic Signals

All this searching for the key to depression underneath the lamplight of serotonin is fine, but we need to remember that it takes a genome. When the book on the genetics of sadness is finally written, it will surely also include entries on the enzymes that synthesize the chemical and on the receptors that take up the signal. It is increasingly apparent, though, that it must include dozens if not hundreds of other chapters that can barely be sketched in outline yet.

The search continues using more traditional approaches. Linkage mapping in pairs of affected twins has turned up a dozen possibilities. This is where researchers look for parts of the genome shared by non-identical twins who both have the disease. As a matter ...