A polymorphism (5-HTTLPR) in the serotonin transporter promoter gene is associated with DSM-IV depression subtypes in seasonal affective disorder

Abstract

Serotonergic mechanisms are thought to play an important role in the pathogenesis of seasonal affective disorder (SAD). The expression of the serotonin transporter (5-HTT) is regulated in part by an insertion/deletion polymorphism in the serotonin transporter gene promoter region (5-HTTLPR). The 5-HTTLPR short allele (s) has been associated with anxietyrelated personality traits and depression, and one study observed an association between the 5-HTTLPR s-allele and SAD and the trait of seasonality. We genotyped 138 SAD patients and 146 healthy volunteers with low seasonality for 5-HTTLPR. No difference between patients and controls was found for genotype distribution and s-allele frequency. However, genotype distribution and allele frequencies were strongly associated with DSM-IV depression subtypes. Melancholic depression was associated with the 5-HTTLPR long (l) allele and atypical depression with the 5-HTTLPR s-allele (two-sided Fisher's exact test: genotype distribution: P¼0.0038; allele frequencies: P¼0.007). Our data are compatible with the hypothesis of a disease process that is not causally related to 5-HTTLPR, but involves 5-HT neurotransmission and 5-HTTLPR somewhere on its way to phenotypic disease expression. Molecular Psychiatry (2003) 8, 942-946. doi:10.1038/sj.mp.4001392Keywords: melancholic; atypical; mood disorders; nosology; genetics Although the impact of seasons on the incidence of mood disorders has been known since ancient times, only in the 1980s of our century seasonal affective disorder (SAD) has been described as a distinct nosologic entity. 1 Typically, patients with SAD, winter type, fulfill the diagnostic criteria for recurrent major depressive or bipolar disorder according to DSM-IV criteria and suffer from depressive episodes during fall and winter, alternating with remission or hypomania/mania in spring and summer. Common symptoms in SAD include depressed mood and the so-called atypical or reverse neurovegetative symptoms, such as hypersomnia, hyperphagia, fatigue, carbohydrate craving, and subsequent weight gain. The tendency to experience seasonal variations in mood, feeding behavior, energy, and social activity has been termed seasonality and can be measured using the global seasonality score (GSS). Although the etiology of SAD is still unclear, a substantial heritable component in seasonality has been shown in twin studies.2,3 A solid body of literature suggests involvement of serotonin (5-HT) in the pathogenesis of SAD. 4 Serotonergic parameters, including central 5-HTT availability, 5 hypothalamic 5-HT concentrations, and peripheral serotonergic parameters 6 show seasonal fluctuations. A variety of research parameters, such as the tryptophan depletion paradigm, 7 hormonal challenge studies, 8 and in vivo imaging of central 5-HTT availability 9 have shown alterations in serotonergic parameters in depressed patients with SAD. Some studies also suggest that serotonergic alterations may be trait markers in SAD.7 Genes involved in serotonergic neurotransmission are thus good cand...

Enhanced Serotonin Transporter Function during Depression in Seasonal Affective Disorder

“…In accordance with previous results (Johansson et al, 2003;Willeit et al, 2003), 5-HTTLPR genotype distribution did not differ significantly between patients with SAD and healthy controls (patients: ll: 22; ls: 38; ss: 13; controls: ll: 26; ls: 35; ss: 9; w 2 (2) ¼ 1.121; p ¼ 0.571). An earlier study reported significant seasonal variations in serotonin uptake velocity in 5-HTTLPR ll homozygous subjects only (Greenberg et al, 1999).…”

A Functional Genetic Variation of the Serotonin (5-HT) Transporter Affects 5-HT1AReceptor Binding in Humans

“…Many but not all studies have suggested an association between the S allele and abnormal mood states/emotional behaviors (Lesch et al, 1996;Mazzanti et al, 1998;Munafo et al, 2003), depressive illness (Willeit et al, 2003), severity of depressive 5HTTLPR*: group allelic effect, F ϭ 4.8, df ϭ 1, 27, p ϭ 0.037; scanner effect, F ϭ 2.3, df ϭ 1, 27, p ϭ 0.1; gender effect, F ϭ 1.4, df ϭ 1, 27, p ϭ 0.3; interaction effects, allele ϫ scanner, F ϭ 0.3, df ϭ 1, 27, p ϭ 0.6; allele ϫ gender, F ϭ 2.5, df ϭ 1, 27, p ϭ 0.1; scanner ϫ gender, F ϭ 0.6, df ϭ 1, 27, p ϭ 0.5; allele ϫ scanner ϫ gender, F ϭ 0.4, df ϭ 1, 27, p ϭ 0.5. 5-HT 1A (Ϫ1018cϾG)**: group allelic effect, F ϭ 0.001, df ϭ 1, 28, p ϭ 0.973; scanner effect, F ϭ 0.16, df ϭ 1, 28, p ϭ 0.9; gender effect, F ϭ 2.1, df ϭ 1, 28, p ϭ 0.2; interaction effects, allele ϫ scanner, F ϭ 1.1, df ϭ 1, 28, p ϭ 0.3; allele ϫ gender, F ϭ 0.6, df ϭ 1, 28, p ϭ 0.4; scanner ϫ gender, F ϭ 1.7, df ϭ 1, 28, p ϭ 0.2.…”

Genetic adaptation of the human circadian clock to day-length latitudinal variations and relevance for affective disorders

“…Finally, in the case of ASD, few SNPs have been associated with this condition in GWAS; thus, the LD-pruned set only contained 10 ASD variants, one of these significantly correlated with Δphotoperiod ( Table 2). As for SAD, no GWAS has been performed; a variable number tandem repeat (VNTR) in the serotonin transporter gene (SLC6A4) promoter, which affects expression, is the only variant reproducibly associated with SAD and seasonality [30][31][32]. We used data from a recent analysis [33] and obtained a significant correlation between the frequency of the 14-repeat (short) allele, which predisposes to SAD [30][31][32], and Δphotoperiod (τ = 0.331, Kendall's correlation P value = 0.00115).…”