Objective: The purpose of the present study was to relate the number of platelet serotonin transporters in unipolar and bipolar patients and in control subjects to two polymorphisms in the serotonin transporter gene: a VNTR in intron 2 and a deletion/insertion in the promoter region.
Method: Density of platelet serotonin transporters was determined by radioligand binding analysis. Genotyping was performed by PCR amplification of polymorphic regions followed by size determination of the obtained fragments.
Results: The control subjects and the two groups of patients were similar with respect to the genotype and allele distribution belonging to the two polymorphisms in the serotonin transporter gene for. An interaction between status (control, unipolar- or bipolar patient) and VNTR genotype regarding the number of platelet serotonin transporters was observed; unipolar patients with the genotype 12/10 had more platelet serotonin transporters than bipolar patients and controls with this genotype. No association related to the polymorphism was found in the promoter region of the serotonin transporter gene.
Conclusion: An association was observed between the polymorphism in intron 2 of the serotonin transporter gene and the number of platelet serotonin transporters. Unipolar patients with a particular genotype had more platelet serotonin transporters than the corresponding controls and bipolar patients.