Besides the MAPT gene duplication referred to above (Rovelet-Lecrux et al., 2010), the other mutations in MAPT which cause FTD either increase the proportion of four repeat tau by altering the splicing of exon 10 of the gene (Hutton et al., 1998), or by reducing the binding of tau to microtubules and thus increasing the concentration of free tau protein (Hong et al., 1998). The gene discussed is MAPT; the disease is frontotemporal dementia.