PDE10A and Huntington disease: This idea that a lack of PDE10A enzyme could cause cAMP signaling disruptions has also been suggested as a cause of the motor and psychiatric deficits seen in Huntington's Disease.43, 44 Competitive inhibitors of PDE10A have been proposed as therapeutic targets to ameliorate psychosis.43, 45 However, if the molecular pathology of psychotic disorders arises from a failure of PDE10A2 to regulate excitability at the membrane, due to mis-expression of PDE10A19, such therapies may be ineffective.