Comparing to patients with PDD, the DLB cases displayed more frequency of fluctuating cognition (28.3% vs. 9.7%, p = 0.001), VH (47.8% vs. 14.0%, p < 0.001) and RBD (55.4% vs. 22.6%, p < 0.001) at the time of diagnosis, while there was no significant difference in APOE ɛ4 allele subgroups (Additional file, Table S1). The gene discussed is APOE; the disease is Lewy body dementia.