SLC6A4 and Anxiety: Otherwise, in the study conducted by Pardo-Lozano et al. (n = 27), subjects carrying the 5HTTLPR l/* (high functionality) genotype experienced increased cardiovascular effects (especially increased heart rate or even tachycardia) than others, and the subjects carrying 5HTTLPR s/s genotype exhibited more negative subjective effects (including dizziness, anxiety, and sedation) than others [39].