3/19/2006
Gene Influences Antidepressant Response
Whether depressed patients will respond to an antidepressant depends, in part, on which version of a gene they inherit, a study led by scientists at the National Institutes of Health (NIH) has discovered. Having two copies of one version of a gene that codes for a component of the brain's mood-regulating system increased the odds of a favorable response to an antidepressant by up to 18 percent, compared to having two copies of the other, more common version.
Since the less common version was over 6 times more prevalent in white than in black patients the researchers suggest that the gene may help to explain racial differences in the outcome of antidepressant treatment.
Everyone inherits two copies of the serotonin 2A receptor gene, one from each parent. A tiny glitch in the gene's chemical sequence results in some people having an adenine (A) at the same point that other people have a guanine (G). So an individual can have gene types AA, AG or GG. Overall, the prevalence of the A version was 38 percent, compared to 62 percent for the G version in this sample. Fourteen percent had AA gene type, 43 percent AG and 43 percent GG. Since the site of variation is located in a stretch of genetic material with no known function, the researchers suspect that it may be just a marker for a still-undiscovered functional variation nearby in the gene.
Based on scores on a depression rating scale, close to 80 percent of patients who had AA responded to the antidepressant, compared to about 62 percent of those with GG. Thus, patients with the AA gene type were 16-18 percent more likely to benefit from the medication. Even patients with AG showed some increased benefit.
NIMH: Gene Influences Antidepressant Response
Since the less common version was over 6 times more prevalent in white than in black patients the researchers suggest that the gene may help to explain racial differences in the outcome of antidepressant treatment.
Everyone inherits two copies of the serotonin 2A receptor gene, one from each parent. A tiny glitch in the gene's chemical sequence results in some people having an adenine (A) at the same point that other people have a guanine (G). So an individual can have gene types AA, AG or GG. Overall, the prevalence of the A version was 38 percent, compared to 62 percent for the G version in this sample. Fourteen percent had AA gene type, 43 percent AG and 43 percent GG. Since the site of variation is located in a stretch of genetic material with no known function, the researchers suspect that it may be just a marker for a still-undiscovered functional variation nearby in the gene.
Based on scores on a depression rating scale, close to 80 percent of patients who had AA responded to the antidepressant, compared to about 62 percent of those with GG. Thus, patients with the AA gene type were 16-18 percent more likely to benefit from the medication. Even patients with AG showed some increased benefit.
NIMH: Gene Influences Antidepressant Response
