Limited power of dopamine transporter mRNA mapping for predicting dopamine transporter availability.

Dopamine transporters (DAT) are transmembrane proteins that translocate dopamine from the extracellular space into presynaptic neurons. We aimed to investigate the predictive power of DAT mRNA for DAT protein expression, measured using positron emission tomography (PET). We performed 18 F-FP-CIT PET scans in 35 healthy individuals. Binding potentials (BP ND ) from the ventral striatum, caudate nucleus, putamen, and middle frontal, orbitofrontal, cingulate, parietal, and temporal cortices were measured. DAT gene expression data were obtained from the freely available Allen Human Brain Atlas derived from six healthy donors. The auto-correlation of PET-derived BP ND s for DAT was intermediate (mean ρ 2  = .66) with ρ 2 ranging from .0811 to 1. However, the auto-correlation of mRNA expression was weak across the probes with a mean ρ 2 of .09-.23. Cross-correlations between PET-derived BP ND s and mRNA expression were weak with a mean ρ 2 ranging from 0 to .22 across the probes. In conclusion, we observed weak associations between DAT mRNA expression and DAT availability in human brains. Therefore, DAT mRNA mapping may have only limited predictive power for DAT availability in humans. However, the difference in distribution of DAT mRNA and DAT protein may influence this limitation.