GBA mutations are the most significant genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB)1, 2, 3; however, penetrance is only 10%–30%.4, 5, 6 PD patients carrying a GBA mutation have an earlier disease onset and a higher risk of dementia.7 The gene discussed is GBA1; the disease is Lewy body dementia.