Meisler et al. [19] found a proband with bipolar affective disorder harboring C9ORF72 gene expansion, whose father had autopsy-proven frontotemporal lobar degeneration (frontotemporal dementia with different pathological subtypes based on tau, TDP, FUS, and C9ORF72-associated dipeptides), and an earlier diagnosis of bipolar affective disorder. The gene discussed is MAPT; the disease is frontotemporal dementia.