title: A family with tau-negative frontotemporal dementia and neuronal intranuclear inclusions linked to chromosome 17.
abstract: Over 30 different mutations have now been identified in MAPt that cause frontotemporal dementia (FTD). However, there are several families with FTD that show definite linkage to the region on chromosome 17 that contains MAPt, in which no mutation(s) has been identified. Although these families could have a complex mutation of the MAPt locus that has evaded detection it is also possible that another gene in this region is associated with FTD. This possibility is supported by neuropathological findings in these families, which consist of neuronal inclusions that are immunoreactive for ubiquitin (ub-ir) but not for tau. In addition to neuronal cytoplasmic inclusions, several chromosome 17-linked families are reported to have ub-ir neuronal intranuclear inclusions (NII); a finding which is uncommon in sporadic FTD. Here, we describe detailed clinical and neuropathological findings in a new large, multigenerational family with autosomal dominant FTD and autopsy proven tau-negative, ub-ir neuronal cytoplasmic and intranuclear inclusions. We have demonstrated that this family is linked to a 19.06 cM region of chromosome 17q21 with a maximum multipoint LOD score of 3.911 containing MAPt. By combining the results of our genetic analysis with those previously published for other families with similar pathology, we have further refined the minimal region to a 3.53 cM region of chromosome 17q21. We did not identify point mutations in MAPt by direct sequencing or any gross MAPt gene alterations using fluorescent in situ hybridization. In addition, tau protein extracted from members of this family was unremarkable in size and quantity as assessed by western blotting. Neuropathological characterization of the ub-ir NII in this family shows that they are positive for promyelocytic leukaemia protein (PML) and SUMO-1 that suggests that these inclusions form in the nuclear body and suggests a possible mechanism of neurodegeneration in tau-negative FTD linked to chromosome 17q21.
authors.affiliation: Department of Pathology, University of British Columbia, Vancouver, Canada.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Mackenzie
authors.forename: Matthew
authors.initials: M
authors.lastname: Baker
authors.forename: Gemma
authors.initials: G
authors.lastname: West
authors.forename: John
authors.initials: J
authors.lastname: Woulfe
authors.forename: Najeeb
authors.initials: N
authors.lastname: Qadi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gass
authors.forename: Ashley
authors.initials: A
authors.lastname: Cannon
authors.forename: Jennifer
authors.initials: J
authors.lastname: Adamson
authors.forename: Howard
authors.initials: H
authors.lastname: Feldman
authors.forename: Caroline
authors.initials: C
authors.lastname: Lindholm
authors.forename: Stacey
authors.initials: S
authors.lastname: Melquist
authors.forename: Rachel
authors.initials: R
authors.lastname: Pettman
authors.forename: A Dessa
authors.initials: AD
authors.lastname: Sadovnick
authors.forename: Emily
authors.initials: E
authors.lastname: Dwosh
authors.forename: Sidney W
authors.initials: SW
authors.lastname: Whiteheart
authors.forename: Michael
authors.initials: M
authors.lastname: Hutton
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Pickering-Brown
mesh_terms: D000368:Aged; D015153:Blotting, Western; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D003704:Dementia / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D045586:Intranuclear Inclusion Bodies / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000648:ultrastructure; D010375:Pedigree; D025801:Ubiquitin / Q000032:analysis; D016875:tau Proteins / Q000032:analysis / Q000235:genetics
chemical_list: D025801:Ubiquitin; D016875:tau Proteins