GCH1 and Parkinsonism: The clinical phenotype of the studied patient strongly evoked DRD due to mutations in GCH1. Next-generation sequencing using Ion proton technology with a panel of 20 genes designed for Parkinsonism and related disorders found a heterozygous nonsense mutation c.181G>T (p.Glu61Ter) in exon 1 of GCH1 in the patient.