Frequencies of LRRK2 variants in Thai patients with Parkinson's disease: evidence for an R1628P founder

Mutations in the leucine rich repeat kinase 2 (LRRK2) gene are associated with familial and idiopathic Parkinson's disease (PD). The occurrence of common LRRK2 mutations is different among differing ethnic groups. The LRRK2 G2385R (c.7153G>R) and R1628P (c.4883G>C) mutations have been shown to be common risk factors for PD in East Asian populations while G2019S (c.6050G>A) is common in Europeans.1 2 Thailand is located in Southeast Asia, geographically close to China. Major Asian diasporas into mainland East Asia have taken place since the prehistoric period until mass Chinese emigration during the Chinese civil war and World War II.3 Thus it is likely that the Chinese and Thai populations may share some regional characteristic genotypes, including LRRK2 variants. These data led us to analyse the frequencies of the common LRRK2 R1628P, G2385R and G2019S mutations in our cohort of idiopathic PD patients. We recruited 154 Thai patients with sporadic PD (males=56.5%, mean age of onset=61.2±9.8 years) and 156 control subjects over 65 years of age without any clinical features of parkinsonism. The research protocol was approved by the ethic committees from all participating hospitals. All patients provided informed consent. The majority of the Thai population comprises indigenous Thai people and Chinese immigrants. To classify the ethnic groups of the population, we divided the cases into three groups: (1) Thai; (2) …