TH and Parkinsonism: Consistent with the essential role of TH in dopamine homeostasis, missense mutations in TH have been previously investigated, providing links with severe Parkinsonism-related phenotypes, such as Segawa’s syndrome, L-DOPA-responsive infantile Parkinsonism, or L-DOPA-responsive dystonia (DRD) in the recessive form (Bademci et al. 2012).