Genetic mutations of the GCH1 gene, which codes for guanosine triphosphate cyclohydrolase I (GTPCH I) [34], the tyrosine hydroxylase (TH) gene [35], and the guanine nucleotide binding protein (GNAL) gene [36] are found in dystonia, and surprisingly share a common mechanism associated with the cyclic cAMP/PKA pathway. The gene discussed is TH; the disease is Dystonia.