DNA was prepared from peripheral blood leukocytes or B-lymphoblastoïd cell lines by standard procedures. The genotyping of the 5-HTTLPR, rs25531 as well as the triallelic intron 2 VNTR (Stin2) (not used in this study) were performed by triplex polymerase chain reaction (PCR) followed by restriction endonuclease digestion as described by29. Briefly, the amplification reaction was performed using three couples of oligonucleotide primers in a final volume of 20 μl containing 20 ng of genomic DNA and using a 0.5 unit of MyTaq™ DNA Polymerase (Bioline, London, UK). After an initial denaturation at 95 °C for 15 min, the amplification cycles consisted of 35 cycles of denaturation at 95 °C for 30 s, annealing at 65.5 °C for 90 s and elongation at 72 °C for 1 min. Subsequently, 8 μl of amplification products were digested with 5U of HpaII (New England Biolabs, Ipswich, MA, USA), in a 20 μl reaction assay containing 1X NEBuffer 1 and 1X BSA at 37 °C for 1 h. Digested and non-digested PCR products were loaded on 3% agarose gel in 1X TBE. The short
