GBA1 and Parkinson disease: In a large study with a European cohort, all exons of GBA were screened in 786 PD patients who had a familial PD history, 605 sporadic PD patients and 391 controls, and an overall GBA carrier frequency of 6.7% was found for the PD patients, including sporadic and familial subjects, compared with 1% of the control individuals (Lesage et al., 2011).