In the FTD group, GFAP and NfL were associated with MMSE decline (estimate [SE], -2.118 [0.566], P < .001 and -2.360 [0.428], P < .001, respectively), whereas p-tau217 was not (estimate [SE], 0.071 [0.418], P = .87). The gene discussed is GFAP; the disease is frontotemporal dementia.