In studiesby Suda et al. and Minalyan et al., ghrelin and its receptor agonist HM01 couldonly improve weight-related nonmotor symptoms of PD; however, ghrelincould also improve the motor symptoms only when there is a transientblockage of dopaminergic (DA) transmission induced by haloperidolin the former study. The gene discussed is GHRL; the disease is Parkinson disease.