Posts Tagged ‘alleles’

Dandelions and Orchids

March 11th, 2011

Dandelions are hardy. Give them a crack on a city sidewalk, and they will thrive. The beautiful orchid, by contrast, is much more delicate. To thrive it needs conditions like those in Costa Rica: warm, sunny, and moist.

Increasingly, research on the human genome suggests that important gene-environment interactions may lead to psychiatric syndromes. An example is that two short alleles on the serotonin-transporter (5-HTT) gene may heighten vulnerability to depression under adverse circumstances.

Why would such vulnerability genes survive? Shouldn’t people who inherit them be adversely selected, so their genes would decrease and die out over generations? Or, might such genetic patterns give evolutionary advantage in selected environments—something like sickle-cell trait making people more resistant to malaria?

Emerging evidence, including data from studies by Penn State scientists, suggests that some genetic patterns, such as two short 5-HTT alleles, might confer behavioral advantages in an optimal environment. People with two short alleles who grow up in nurturing, intact families, with educational and economic privilege, may actually show greater resilience and creativity, while others with the same genetic pattern, who come from poverty and dysfunction, may do worse than average. If this theory is correct, the people with two short 5-HTT alleles are “orchids,” doing beautifully in ideal environments, but worse than average in bad environments. The majority of people, who have either a short and a long or two long alleles, are “dandelions,” doing moderately well in a broad range of environments.

As I write periodically in BTP, we stand on the threshold of dramatic and exciting breakthroughs in understanding the brain. In time, these discoveries should help people who suffer from psychiatric syndromes—including autism, ADHD, depression, and PTSD

Alan J. Gelenberg, M.D.
Biological Therapies in Psychiatry
Professor and Chair, Psychiatry, Penn State University
Journal of Clinical Psychiatry