Psychological Medicine



The serotonin transporter promoter repeat length polymorphism, seasonal affective disorder and seasonality


C. JOHANSSON a1c1, M. WILLEIT a1, R. LEVITAN a1, T. PARTONEN a1, C. SMEDH a1, J. DEL FAVERO a1, S. BEL KACEM a1, N. PRASCHAK-RIEDER a1, A. NEUMEISTER a1, M. MASELLIS a1, V. BASILE a1, P. ZILL a1, B. BONDY a1, T. PAUNIO a1, S. KASPER a1, C. VAN BROECKHOVEN a1, L.-G. NILSSON a1, R. LAM a1, M. SCHALLING a1 and R. ADOLFSSON a1
a1 Department of Molecular Medicine, Karolinska Institute and Karolinska Hospital and Department of Psychology, Stockholm University, Stockholm, and Department of Clinical Sciences, Division of Psychiatry, University of Umeå, Umeå, Sweden; Department of General Psychiatry, Vienna University, Vienna, Austria; Department of Psychiatry, University of Toronto, Toronto and Department of Psychiatry, University of British Columbia, Vancouver, Canada; Departments of Mental Health and Alcohol Research, and Human Molecular Genetics, National Public Health Institute Helsinki, Finland; Department of Molecular Genetics, Flanders Inter-university Institute for Biotechnology (VIB8), University of Antwerp, Antwerp, Belgium; Mood and Anxiety Disorders Preogram, National Institute of Mental Health, Bethesda, MD, USA; and Department of Neurochemistry, Ludwig Maximilians University, Munich, Germany

Article author query
johansson c   [PubMed][Google Scholar] 
willeit m   [PubMed][Google Scholar] 
levitan r   [PubMed][Google Scholar] 
partonen t   [PubMed][Google Scholar] 
smedh c   [PubMed][Google Scholar] 
del favero j   [PubMed][Google Scholar] 
bel kacem s   [PubMed][Google Scholar] 
praschak-rieder n   [PubMed][Google Scholar] 
neumeister a   [PubMed][Google Scholar] 
masellis m   [PubMed][Google Scholar] 
basile v   [PubMed][Google Scholar] 
zill p   [PubMed][Google Scholar] 
bondy b   [PubMed][Google Scholar] 
paunio t   [PubMed][Google Scholar] 
kasper s   [PubMed][Google Scholar] 
van broeckhoven c   [PubMed][Google Scholar] 
nilsson l-g   [PubMed][Google Scholar] 
lam r   [PubMed][Google Scholar] 
schalling m   [PubMed][Google Scholar] 
adolfsson r   [PubMed][Google Scholar] 

Abstract

Background. Conflicting results have been reported in previous association studies of the serotonin transporter promoter repeat length polymorphism (5-HTTLPR), seasonal affective disorder (SAD) and seasonality (seasonal variations in mood and behaviour). The aim of this study was to test for association in new case–control and population-based materials, and to perform a combined analysis of all published studies of 5-HTTLPR and SAD.

Method. One hundred and forty-seven new SAD cases and 115 controls were genotyped for 5-HTTLPR and in total 464 patients and 414 controls were included in the pooled analysis. In addition, 226 individuals selected for unusually high or low seasonality scores from a population based material and 46 patients with non-seasonal depression were analysed. Different genetic models were tested and seasonality was analysed both as a qualitative (high v. low) and as a quantitative trait in the different sample sets.

Results. No association between 5-HTTLPR and SAD was found in the new case–control material, in the combined analysis of all samples, or when only including 316 patients with controls (N=298) selected for low seasonality. A difference was detected between the population based high and low seasonality groups, when assuming a recessive effect of the short allele (20% and 10% short allele homozygotes, respectively, OR (95% CI): 2·24 (1·03–4·91)). Quantitative analysis of seasonality revealed no association with 5-HTTLPR in any sample set.

Conclusions. These results do not suggest a major role of the short variant of 5-HTTLPR in susceptibility to SAD, but provide modest evidence for an effect on seasonality.


Correspondence:
c1 Dr C. Johansson, Neurogenetics Unit, CMM L8:00, Karolinska Hospital, S-171 76 Stockholm, Sweden.


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