ApoE4 carrier status increased the likelihood of Aβ pathology, both in cases with tau and TDP43 pathology (chi-squared test, P = .001 and chi-squared test, P = .006, respectively): for the tau+ ApoE4+ patients with FTD and available neuropathology data, 15 of 21 (71.4%) had Aβ copathology compared with 11/42 (26.2%) ApoE4− tau+ cases (chi-squared test, P = .001); for the TDP+ ApoE4+ FTD cases, 8/13 (61.5%) had Aβ copathology compared with 10/47 (21.3%) of ApoE4− TDP+ cases (chi-squared test, P = .013). The gene discussed is MAPT; the disease is frontotemporal dementia.