Cerebral Cortex Advance Access originally published online on November 19, 2008
Cerebral Cortex 2009 19(8):1751-1760; doi:10.1093/cercor/bhn202
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Cortical Atrophy and Language Network Reorganization Associated with a Novel Progranulin Mutation
1 Neurogenetics, 2 Neuroimaging Laboratories, Division of Neurosciences, Center for Applied Medical Research, University of Navarra, Pamplona, 31008 Spain, 3 Department of Neurology, Hospital do Salnés, Pontevedra, 36619 Spain, 4 Department of Psychiatry, Washington University, St. Louis, MO 63130, USA, 5 Department of Neurology, Clínica Universitaria de Navarra, University of Navarra, Pamplona, 31008 Spain, 6 Department of Psychodiagnosis, Clínica Universitaria de Navarra, University of Navarra, Pamplona, 31008 Spain, 7 Department of Nuclear Medicine, Clínica Universitaria de Navarra, University of Navarra, Pamplona, 31008 Spain
Address correspondence to Dr Pau Pastor, MD, PhD, Neurogenetics Laboratory, Division of Neurosciences, Center for Applied Medical Research (CIMA), Pio XII 55, 31008-Pamplona (Navarra) Spain. Email: ppastor{at}unav.es.
Progressive nonfluent aphasia (PNFA) is an early stage of frontotemporal degeneration. We identified a novel Cys521Tyr progranulin gene variant in a PNFA family that potentially disrupts disulphide bridging causing protein misfolding. To identify early neurodegeneration changes, we performed neuropsychological and neuroimaging studies in 6 family members (MRI [magnetic resonance imaging], fMRI [functional MRI], and 18f-fluorodeoxygenlucose positron emission tomography, including 4 mutation carriers, and in 9 unrelated controls. Voxel-based morphometry (VBM) of the carriers compared with controls showed significant cortical atrophy in language areas. Grey matter loss was distributed mainly in frontal lobes, being more prominent on the left. Clusters were located in the superior frontal gyri, left inferior frontal gyrus, left middle frontal gyrus, left middle temporal gyri and left posterior parietal areas, concordant with 18FDG-PET hypometabolic areas. fMRI during semantic and phonemic covert word generation (CWGTs) and word listening tasks (WLTs) showed recruitment of attentional and working memory networks in the carriers indicative of functional reorganization. During CWGTs, activation in left prefrontal cortex and bilateral anterior insulae was present whereas WLT recruited mesial prefrontal and anterior temporal cortex. These findings suggest that Cys521Tyr could be associated with early brain impairment not limited to language areas and compensated by recruitment of bilateral auxiliary cortical areas.
Key Words: 18FDG-PET • fMRI • frontotemporal dementia • language • primary progressive aphasia • progranulin gene
Dr. Maria A. Pastor and Dr. Pau Pastor contributed equally to this article.