Striatal dopamine transporter availability and DAT-1 gene in adults with ADHD: no higher DAT availability in patients with homozygosity for the 10-repeat allele

Abstract

In 29 adults with attention deficit hyperactivity disorder (ADHD) striatal dopamine transporter (DAT) availability was assessed by [99mTc]TRODAT-1 SPECT and correlated with 3′ VNTR polymorphism of the DAT gene on chromosome 5p15.3. Seventeen patients showed homozygosity for the 10-repeat allele, two homozygosity of the 9 allele and 10 were heterozygous (9–10). No statistically significant difference in DAT availability was found between patients with 10–10 carriers (DAT 1.28±0.34) and with at least one 9 allele (DAT 1.31±0.27); when smokers were excluded, DAT availability was 1.38±0.28 in the 10–10 carriers (n=12) and 1.42±0.19 in the 9–10 and 9–9 carriers (n=7). In conclusion, no higher striatal DAT was found in patients with homozygosity of the 10 allele of the DAT gene in this study. These results differ from a study in 11 Korean children with ADHD, in which 10–10 carriers showed higher DAT availability in [123I]IPT SPECT. Discrepancies may be explained by differences in patient's age, ethnical differences, different imaging techniques or the limited number of patients included in both studies.