Currently our group, in collaboration with the CHDI foundation, has completed a cross-sectional and longitudinal PET study (ClinicalTrials Identifier: NCT02061722) in a large cohort of HD mutation carriers with the intention of measuring PDE10A in relation to D2 receptors across all different disease stages bearing in mind in the study design the necessity to develop a pharmacodynamic biomarker. This evidence concerns the gene PDE10A and Huntington disease.