A translocation within a region of the human FGF14 gene that is nearly identical to the syntenic segment of Fgf14 disrupted by the tau transgene in rTg4510 has been reported to be linked to phenotypes ranging from ataxia (mother) to microcephaly and severe mental retardation (proband)25, suggesting that these types of FGF14 disruptions may increase susceptibility to significant loss of brain mass and function. This evidence concerns the gene MAPT and microcephaly.