By combining synergistic β<sub>1</sub>-adrenergic antagonism, VMAT2-mediated dopamine modulation, and VMAT1 inhibition, SOM3355 may address monoamine neurotransmitter imbalances within basal ganglia and cortical circuits involved in motor and neuropsychiatric manifestations of HD. The gene discussed is SLC18A2; the disease is Huntington disease.