In addition, many groups found a downregulation of DA markers, such as TH, VMAT2, DAT, and PITX3 both in hMO obtained from idiopathic and LRRK2-associated PD: this observation suggests that at the basis of the PD there is an alteration in the DA neuron development process [52,55]. The gene discussed is PITX3; the disease is Parkinson disease.