Prediction of dopamine transporter binding availability by genotype: a preliminary report.

Evidence of a relationship between genotype and binding availability was assessed for the dopamine and serotonin transporter genes. The authors assessed dopamine transporter genotype at the SLC6A3 3' variable number of tandem repeats (VNTR) polymorphism and serotonin transporter genotype at the SLC6A4 promotor VNTR polymorphism in 30 healthy subjects who also underwent single photon emission computed tomography with [(123)I]beta-CIT. Subjects homozygous for the 10-repeat allele at the SLC6A3 locus demonstrated significantly lower dopamine transporter binding than carriers of the nine-repeat allele. There was no effect of SLC6A4 genotype upon serotonin transporter binding. These findings suggest that genetic variation at the SLC6A3 3' VNTR polymorphism may modify dopamine transporter function.