SLC6A3 and Borderline personality disorder: While both the 9,9 and 9,10 variants of the DAT1 allele were found to be associated with BPD to a significantly greater extent than the 10,10 variant in an uncontrolled model, in a multiple model the incidence of BPD associated with the 9,9 variant was not significantly greater than the incidence of BPD associated with the 10,10 variant.