LRRK2 and Parkinson disease: In prior studies of small cohorts from South America our group and others have shown that the frequency of p.G2019S and p.R1441G varies substantially across different countries.3, 12, 17, 18 In a small pilot study we also observed that the LRRK2-p.Q1111H SNP, which is common in some Latin American populations, occurred at an increased frequency in PD patients, though the difference was not quite significant.19 Thus, whether this variant represents a PD risk factor in Latino populations remains unclear.