Journal Article

A family with tau-negative frontotemporal dementia and neuronal intranuclear inclusions linked to chromosome 17

Ian R. Mackenzie, Matthew Baker, Gemma West, John Woulfe, Najeeb Qadi, Jennifer Gass, Ashley Cannon, Jennifer Adamson, Howard Feldman, Caroline Lindholm, Stacey Melquist, Rachel Pettman, A. Dessa Sadovnick, Emily Dwosh, Sidney W. Whiteheart, Michael Hutton and Stuart M. Pickering-Brown

in Brain

Published on behalf of The Guarantors of Brain

Volume 129, issue 4, pages 853-867
Published in print April 2006 | ISSN: 0006-8950
Published online January 2006 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awh724
A family with tau-negative frontotemporal dementia and neuronal intranuclear inclusions linked to chromosome 17

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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.

Keywords: frontotemporal dementia; ubiquitin; linkage analysis; neuronal intranuclear inclusions; FTD = frontotemporal dementia; NII = neuronal intranuclear inclusions; NSF = N-ethylmaleimide-sensitive factor; PML = promyelocytic leukaemia protein; ub-ir = immunoreactive for ubiquitin

Journal Article.  8881 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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