Clinicopathologic features of frontotemporal dementia with Progranulin sequence variation

Background: Frontotemporal lobar degeneration with ubiquitin-immunoreactive (ub-ir) inclusions (FTLD-U) has been associated with frontotemporal dementia (FTD) and ALS. Recently, mutations in Progranulin ( PGRN ), predicted to cause premature truncation of the PGRN coding sequence, were found in patients with inherited FTLD-U and ub-ir neuronal intranuclear inclusions (NII). Objective: To describe clinical, pathologic, and genetic features of three FTD patients having either a family history of FTD (A.III.1 and B.II.1) or of ALS (C.III.1). Methods: Patients underwent a single clinical assessment, MRI, and [ 18 F]fluorodeoxyglucose PET brain scan. Neuropathologic examination and genetic analyses were carried out. Results: Patients presented clinically with the behavioral variant of FTD. Language dysfunctions were marked with comprehension being particularly affected. Neuroimaging revealed frontotemporal atrophy and glucose hypometabolism, with predominant left-side involvement, in Patients A.III.1 and B.II.1. Subject C.III.1 displayed mild atrophy and symmetric anterior hypometabolism. All patients were neuropathologically diagnosed with FTLD-U. Ub-ir NII were noted in Patients A.III.1 and B.II.1 but were absent in Patient C.III.1. The following PGRN sequence variations were found: IVS6-2A→G (A.III.1), R493X (B.II.1), and R433W (C.III.1). IVS6-2A→G may lead to skipping of exon 7 with consequent frameshift of the coding sequence and premature termination of PGRN translation. Conclusions: We have found two PGRN mutations associated with FTD, in affected individuals who are members of families with possible autosomal dominant FTD. A third PGRN sequence variation (R433W) was found in an FTD patient with family history of ALS.