The objective of this study was to analyze association of the serotonin transporter gene 5–HTTLPR polymorphism on lifetime depression and alcohol dependence in the Collaborative Study on the Genetics of Alcoholism sample. We conducted family-based association analyses in 1913 Caucasians genotyped for the 5–HTTLPR polymorphism. We found evidence for association of the short allele with depression, but no evidence of association with alcohol dependence. On the basis of the evidence that the effect of this polymorphism may be moderated by stressful life events, we classified individuals for the presence and/or absence of stress, as defined by unemployment, relationship problems, or poor health. The evidence for the association with lifetime depression was limited to the group of individuals who had experienced stress, paralleling the direction of effects originally reported by Caspi and colleagues. No evidence was found for the association with alcohol dependence in either the stress or the no-stress groups.
aDepartment of Psychiatry, Washington University in St. Louis, St. Louis, Missouri
bDepartment of Psychology, Washington University in St. Louis, Missouri
cInstitute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana
dDivision of child Psychiatry, University of Iowa College of Medicine, Iowa City, Iowa
eDepartment of Psychiatry, University of California, San Diego VA Medical Center, San Diego, California
fDepartment of Psychiatry, University of Connecticut Health Center, Farmington, Connecticut, USA
gDepartments of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
Correspondence and requests for reprints to Dr Danielle M. Dick, PhD, Department of Psychiatry, Washington University School of Medicine, Box 8134, 660, South Euclid Avenue, St Louis, MO 63110, USA
Tel: +1 314 286 2297; fax: +1 314 286 2213; e-mail: firstname.lastname@example.org
Sponsorship: The Collaborative Study on the Genetics of Alcoholism (COGA) is supported by the NIH Grant U10AA08401 from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and the National Institute on Drug Abuse (NIDA). Partial support was also provided by NCRR Grant M01- RR06192 to the University of Connecticut School of Medicine GCRC.
Received 31 May 2006 Revised 12 July 2006 Accepted 9 August 2006