DNA was extracted from saliva using the Oragene DNA saliva kit (DNA Genotek, Ottawa, Ontario, Canada). OXTR SNP rs2254298 was amplified using the primers 5′-TGA AAG CAG AGG TTG TGT GGA CAG G-3′ and 5′-AAC GCC CAC CCC AGT TTC TTC-3′. The PCR reactions were carried out in a final volume of 15μl consisting of 50ng of genomic DNA, 50ng each of sense and antisense primers, 7.5ul of Taq PCR Master mix (Qiagen, Cat.#201445) and 10% DMSO. The PCR conditions included an initial denaturation step at 95°C for 5 min, followed by 35 cycles of denaturation at 95°C for 30 s., annealing at 58°C for 45 s. and extension at 72°C for 1 min, with a final extension of 10 min at 72°C. 7.5 μl of the 307 bp PCR products was digested at 65°C for 3 hours with 5 U of the restriction enzyme BsrI (New England Biolabs, Cat#R0527L). The products were electrophoresed through 10% Polyacrylamide gel(Acrylamide/bis-Acrylamide ratio 19:1) at 150 V for 40 min. 10bp marker was used to measure the fragments size. The A allele yields 164bp,
