Alternative spicing of tau (Andreadis, 2005; Hong et al., 1998; Janke et al., 1999; Roberson et al., 2007), which forms NFTs and is mutated in Frontotemporal Dementia (Goedert et al., 1998; Grover et al., 2003; Grundke-Iqbal et al., 1986; Hutton et al., 1998; Kowalska et al., 2002; Spillantini and Goedert, 1998; Stanford et al., 2003; Yasuda et al., 2000), leads to expression of tau isoforms with three or four microtubule binding domains (3R and 4R, respectively). The gene discussed is MAPT; the disease is frontotemporal dementia.