Monday, May 01, 2006

Genetic Influence for Depression

New York Times magazine has an interesting piece looking at how both genetics and environment impact depression.

The breakthrough moment for GxE came in 2003, when Moffitt and her husband and co-investigator, Avshalom Caspi, published a paper in Science that discussed the relationship between the gene, 5-HTT, and childhood maltreatment in causing depression. Scientists have determined that 5-HTT is critical for the regulation of serotonin to the brain. Proper regulation of serotonin helps promote well-being and protects against depression in response to trauma or stress. In humans, each 5-HTT gene has two alleles, and each allele occurs in either a short or a long version. Scientists are still figuring out how the short allele affects serotonin delivery, but it seems that people with at least one short 5-HTT allele are more prone to depression. And since depression is associated with unemployment, struggling relationships, poor health and substance abuse, the short allele could contribute to a life going awry.

About one-third of the white population have two copies of the protective long allele. About one-half have one long allele and one short one. And about 17 percent have two short alleles. (African-Americans are less likely to have a short allele; Asians are more likely.) In their 2003 study, Caspi and Moffitt looked at 847 New Zealand adults and found a link between having at least one short 5-HTT allele and elevated rates of depression for people who had been mistreated as children or experienced several "life stresses" — defined as major setbacks with jobs, housing, relationships, health and money. Having two short alleles made it highly likely that people who had been mistreated or exposed to unhinging stress would suffer depression. One short allele posed a moderate risk of depression in these circumstances. Two long alleles, on the other hand, gave their carriers a good chance of bouncing back under negative circumstances.
So it takes a bad experience in life to actually trigger the effects, but if you have the good genes, your chance of handling the event go up quite a bit.
Neurobiological research on mice and rats has begun to look at the effect that the 5-HTT gene has on the brain at the molecular level. Eventually, a designer drug might succeed in mimicking precisely what the long-allele variation of 5-HTT does to foster resilience.

Next month, NeuroMark will begin selling the 5-HTT test to people whose doctors request it.
I would like to understand more of how the genes cause the changes. Looks like they are investigating that. And here is another candidate for gene testing. Wouldn't you want to know what version of this gene you have? Or wouldn't you want to know what version your kids have? Can't wait till somebody offers a service where they check for like 200 or 1,000 genes at a time and you can just pay a $500 fee to find out how you stack up genetically.

via New York Times Magazine

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