Friday, December 25, 2009

MAPT and types of tau

Patients with MAPT all have neuronal or glial tau inclusions, but phenotype can vary even among relatives with the disease.  Types include s Picks, s CBD, s PSP and s AGD. 
Tau is divided into 3-tau and 4-tau depending on the number and type of binding sites available.  3Repeat tau is associated with Picks, and 4R tau is associated with CBD, PSP, AGD whereas AD has isoforms of both 3rtau and 4r tau. Thus the neuropathologic diagnosis depends not only on immunostaining but also genotyping of MAPT.
Phenotypes of patients with progranulin mutation are varied and include CBD, AD, MCI, PDD, DLB, FTD+/- Parkinsonism and progressive aphasia syndromes.
Genetically, all PRGN mutations cause premature termination codons, This induces nonsense mediated decay or true haploinsufficiency.