Clinical, neuropathological, and genetic characteristics of the novel IVS9+1delG GRN mutation in a patient with frontotemporal dementia.

Frontotemporal lobar degeneration (FTLD) refers to a clinically, pathologically, and genetically heterogeneous group of dementias that arises from the degeneration of the frontal and temporal lobes. Mutations in the progranulin gene (GRN) are a major cause of FTLD with TDP-43 inclusions. Herein, we describe the clinical, neuropathological, and genetic findings in a case of autosomal dominant behavioral variant of frontotemporal dementia (bvFTD) with asymmetrical parkinsonism and prominent visuospatial deficits that carries a novel GRN mutation. This case highlights important clinical characteristics that seem to be common in FTLD GRN-associated patients, such as asymmetrical parkinsonism and parietal symptoms, and that are correlated to the pathological involvement of striatum (rather than substantia nigra in our case) and parietal lobe. We also emphasize that plasma progranulin level can be useful to infer about the pathogenicity of new GRN mutations.