We show that cognitive impairment and psychiatric symptoms in HD are modified by polymorphisms in the monoamine oxidase A (MAOA) and catechol-O-methyltransferase (COMT) genes and by the 4p16.3 B haplotype.
We therefore measured, with anatomical resolution, MAO-A and -B activities in 5 cases of HD (severity grades 1-3) and age-matched controls by quantitative enzyme radioautography using radiolabeled enzyme inhibitors (3)H-Ro 41-1049 and (3)H-lazabemide, respectively, as high-affinity ligands in vitro.MAO-A was increased significantly (ca.