SLC6A3 and Borderline personality disorder: Conversely the effect of the presence of a particular variant of the DAT1 gene may “cancel” the effect of another variant of the HTR1A gene: for example the odds of BPD occurrence in patients with the 9,10 variants of the DAT1 gene, and the C,G variants of the HTR1A gene are within 18% of the odds of BPD occurrence in a patient with the reference categories of the 10,10 variant of the DAT1 gene and the G,G variant of the HTR1A gene.