32.
Background
Many cases of frontotemporal dementia (FTD) are familial, often with an autosomal dominant pattern of inheritance. Some are
due to a mutation in the tau- encoding gene, on chromosome 17, and show an accumulation of abnormal tau in brain tissue (FTDP-17T).
Most of the remaining familial cases do not exhibit tau pathology, but display neuropathology similar to patients with dementia
and motor neuron disease, characterized by the presence of ubiquitin-immunoreactive (ub-ir), dystrophic neurites and neuronal
cytoplasmic inclusions in the neocortex and hippocampus (FTLD-U). Recently, we described a subset of patients with familial
FTD with autopsy-proven FTLD-U pathology and with the additional finding of ub-ir neuronal intranuclear inclusions (NII).
NII are a characteristic feature of several other neurodegenerative conditions for which the genetic basis is abnormal expansion
of a polyglutamine-encoding trinucleotide repeat region. The genetic basis of familial FTLD-U is currently not known, however
the presence of NII suggests that a subset of cases may represent a polyglutamine expansion disease.
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