MAPT and Intellectual disability: However, a neurodevelopmental predisposition to dementia has been observed in non-demented pre-symptomatic family members with an FTDP-17 mutation (Geschwind et al., 2001), and microdeletions surrounding the MAPT locus have been linked to intellectual disability, suggesting that tau might be involved in the regulation of early functions during development (Sapir et al., 2012).