Figure from (Pergadia et al., 2011). Click on image for a larger view.
One of the more measured and accurate press releases I've seen in a while was issued by Washington University in St. Louis (WUSTL) to announce the publication of a paper (Pergadia et al., 2011) in the American Journal of Psychiatry:
Researchers Identify DNA Region Linked to DepressionThe independent companion paper from Kings College appeared at the same time in AJP (Breen et al., 2011). The press release continues:
ScienceDaily (May 15, 2011) — Researchers at Washington University School of Medicine in St. Louis and King's College London have independently identified DNA on chromosome 3 that appears to be related to depression.
"What's remarkable is that both groups found exactly the same region in two separate studies," says senior investigator Pamela A. F. Madden, PhD, professor of psychiatry at Washington University. "We were working independently and not collaborating on any level, but as we looked for ways to replicate our findings, the group in London contacted us to say, 'We have the same linkage peak, and it's significant.'"And next we have cautious statement warning us that this isn't "the depression gene." Particularly measured, in my view, is the caveat that a cure for depression isn't imminent:
Madden and the other researchers believe it is likely that many genes are involved in depression. While the new findings won't benefit patients immediately, the discovery is an important step toward understanding what may be happening at the genetic and molecular levels, she says.This is quite different from Irresponsible Press Release Gives False Hope to People With Tourette's, OCD, and Schizophrenia, which claimed that a single unit recording study in two monkeys trained to perform a visual target discrimination task (Lennert & Martinez-Trujillo, 2011) "has brought new hope to these patients."
Instead, it's explained that the WUSTL and King's College researchers haven't even identified a specific gene:
From two different data sets, gathered for different purposes and studied in different ways, the research teams found what is known as a linkage peak on chromosome 3. That means that the depressed siblings in the families in both studies carried many of the same genetic variations in that particular DNA region.Unlike many genetic findings, this particular DNA region has genome-wide significance. Often when researchers correct statistically for looking across the entire genome, what appeared originally to be significant becomes much less so. That was not the case with these studies.Although neither team has isolated a gene, or genes, that may contribute to depression risk, the linkage peak is located on a part of the chromosome known to house the metabotropic glutamate receptor 7 gene (GRM7). Some other investigators have found suggestive associations between parts of GRM7 and major depression.The press release ends on an exciting yet cautious note:
"The findings are groundbreaking," says McGuffin, senior author of that study. "However, they still only account for a small proportion of the genetic risk for depression. More and larger studies will be required to find the other parts of the genome involved."
Kudos to Jim Dryden, Associate Director of Broadcast Services.
G. Breen, B. T. Webb, A. W. Butler, E. J. C. G. van den Oord, F. Tozzi, et al. A Genome-Wide Significant Linkage for Severe Depression on Chromosome 3: The Depression Network Study. American Journal of Psychiatry, 2011; DOI: 10.1176/appi.ajp.2011.10091342
Lennert, T., & Martinez-Trujillo, J. (2011). Strength of Response Suppression to Distracter Stimuli Determines Attentional-Filtering Performance in Primate Prefrontal Neurons Neuron, 70 (1), 141-152 DOI: 10.1016/j.neuron.2011.02.041
M. L. Pergadia, A. L. Glowinski, N. R. Wray, A. Agrawal, S. F. Saccone, et al. A 3p26-3p25 Genetic Linkage Finding for DSM-IV Major Depression in Heavy Smoking Families. American Journal of Psychiatry, 2011; DOI: 10.1176/appi.ajp.2011.10091319
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