A variation on chromosome 3 can cause depression, scientists from the UK and USA reveal, describing their discovery as the first compelling evidence of a genetic link to depression. The researchers from King’s College London, England, and Washington University, USA, reported their findings in the American Journal of Psychiatry.

The authors explain that about 1 in every 5 individuals is affected at some time in his/her life by major depression. By 2020, experts believe depression will be the disorder with the greatest disease burden worldwide; rivalling heart disease. 4% of people are affected by recurring and severe depression – these people are particularly difficult to treat.

According to several family studies, in over 40% of cases there is a genetic link to depression risk.

Lead author, Dr Gerome Breen said:

“In a large number of families where two or more members have depression we found robust evidence that a region called chromosome 3p25-26 is strongly linked to the disorder. These findings are truly exciting as possibly for the first time we have found a genetic locus for depression.”

The authors stress that their new findings would not have occurred without the contributions of scientists from the USA, UK, Germany, Italy, Denmark, Switzerland, the Netherlands and Finland.

The King’s College researchers gathered data over a ten-year period on 800 families with recurrent depression from the Depression Network, while those at Washington University analyzed depression and smoking in several families in Finland and Australia. Both studies were carried out independently, without any liaison.

Dr Breen said:

“Though these findings will not result in a test for depression they will help us track down specific genes that are altered in people with this disease. This breakthrough in understanding the risk for depression may get us closer to developing more effective therapies though patients should not expect to see these available for 10-15 years.

Any one of 40 genes in chromosome 3p25-26 could be responsible so we are currently conducting detailed sequencing examinations in 40 of the families involved, to identify specific genes and variations that are causing the linkage. Results of these studies should be available next year.

Peter McGuffin, senior author, said:

“These findings are ground breaking as until now few, if any, regions of the genome have been shown to contribute to depression risk. We acknowledge however, that our finding represents only a small part of the genetic risk for depression and more and larger studies will be required to find the other parts of the genome involved.

Dr Michele Pergadia, lead author, of Psychiatry at Washington University said:

“I think we are just beginning to make our way through the maze of influences on depression and this is an important step toward understanding what may be happening at the genetic and molecular levels. Our future research may focus on trying to learn more about how heavy smoking and depression are linked in this area.”

Dr Breen concluded:

“What is remarkable is that two different data sets, gathered for different purposes and studied in different ways found exactly the same region. Normally in genetic studies of depression, replication of findings is very difficult and frequently takes years to emerge, if ever. It shows that family studies hold considerable promise for genetic research in this area.”

“Genome-Wide Association Study of Major Recurrent Depression in the U.K. Population”
Cathryn M. Lewis, Ph.D., Mandy Y. Ng, Ph.D., Amy W. Butler, Ph.D., Sarah Cohen-Woods, Ph.D., Rudolf Uher, M.D., Ph.D., M.R.C.Psych., Katrina Pirlo, B.Sc., Michael E. Weale, Ph.D., Alexandra Schosser, M.D., Ph.D., Ursula M. Paredes, Ph.D., Margarita Rivera, Ph.D., Nicholas Craddock, F.R.C.Psych., Ph.D., Mike J. Owen, F.R.C.Psych., Ph.D., Lisa Jones, Ph.D., Ian Jones, M.R.C.Psych., Ph.D., Ania Korszun, Ph.D., M.D., M.R.C.Psych., Katherine J. Aitchison, M.R.C.Psych., Ph.D., Jianxin Shi, Ph.D., John P. Quinn, Ph.D., Alasdair MacKenzie, Ph.D., Peter Vollenweider, M.D., Gerard Waeber, M.D., Simon Heath, Ph.D., Mark Lathrop, Ph.D., Pierandrea Muglia, M.D., Michael R. Barnes, Ph.D., John C. Whittaker, Ph.D., Federica Tozzi, M.D., Florian Holsboer, M.D., Ph.D., Martin Preisig, M.D., M.P.H., Anne E. Farmer, M.D., F.R.C.Psych., Gerome Breen, Ph.D., Ian W. Craig, Ph.D., and Peter McGuffin, F.R.C.P., F.R.C.Psych., Ph.D.
Am J Psychiatry 2010; 167:949-957 (online) June 1, 2010; doi: 10.1176/appi.ajp.2010.09091380

Written by Christian Nordqvist