GBA1 and Parkinson disease: Similar results were also highlighted in an earlier publication from the same group, where cognitive and axial impairment were significantly more pronounced in the group of 15 GBA mutation carriers on longitudinal follow-up after GPi or STN-DBS.20 A German study identified four DBS-treated PD patients carrying a GBA mutation through screening, matched each GBA case to two non-carriers and compared clinical data from 4–10 years of follow-up.66 Both mutation carriers and non-carriers reduced their LEDD and had well controlled motor fluctuations and dyskinesias postoperatively.