A whole genome association study of unipolar depression

Depression is a very common disorder and is a major public health problem in the UK and throughout the world. There is good evidence from studies looking at families and twins that there is a substantial genetic contribution to depression, particularly recurrent disorder. Almost certainly the genetic component of depression results from many genes of small effect and there is also a complicated interplay with environmental factors such as distressing events. As yet we know little about which genes are involved in depression and the study aims to find at least to some of them. We will utilise a new technology that enables a search throughout the genome using approximately half a million markers. Finding genes involved in depression has great potential benefits for clinical practice, first in better understanding the biology of depression and thereafter in discovering better, safer medications.

We will perform a two stage whole genome scan using the new Affymetrix 500K chip with a DNA pooling on pools stratified by sex.A subset will also be stratifed by presence or absence of adversity. SNPs identified by pooling experiments in both (DeCC and GENESiS) samples will be followed up by individual genotyping.
The samples that will be used have both been funded by previous MRC grants:
1. the Depression case-control ( DeCC)study consisting of over 1500 cases of recurrent clinical depressive disorder and 1500 controls screened for absence of psychiatric illness.
2. subjects from the population based GENESiS study who fall within the top 10% (N. = 570) and the bottom 10% (N. = 595) on a composite index designed to detect depressive and anxiety symptoms.