Study of GCH1 and TH genes in Chinese patients with Parkinson's disease.

Whole-exome sequencing of Parkinson's disease (PD) patients has revealed that the frequency of GTP-cyclohydrolase I (GCH1) variants was significantly higher in patients than in controls. GCH1 rs11158026 was also found to increase the risk of PD. To investigate genetic contribution of dopa-responsive dystonia-related genes to PD, GCH1, and tyrosine hydroxylase (TH) were tested in PD patients. A total of 859 study subjects comprising 421 patients with PD and 438 controls were recruited. For GCH1 gene, one known variant (c.239G > A, p.S80N) was detected in a patient who was diagnosed with PD clinically. In TH, 3 heterozygous variants, c.1495G > A (p. V499M, rs1800033), c.334 A > G (p.V112M, rs6356), and c.813 G > A (p. K271K, rs6357), were identified. After stratification by age, the frequency of rs6356G allele was significantly lower (p = 0.041) for the late-onset PD group than controls. Our results indicate that to analyze the relationship between dopa-responsive dystonia-related genes and PD, it is important to screen GCH1 and test rs6356 of TH in a larger sample.