Voxel-based morphometry in frontotemporal lobar degeneration with ubiquitin-positive inclusions with and without progranulin mutations

Background: Mutations in the progranulin gene (PGRN) have recently been identified as a cause of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) in some families. Objective: To determine whether there is a difference in the patterns of atrophy in FTLD-U cases with and without PGRN mutations. Design: Case-control study. Setting: Brain bank of a tertiary care medical center. Patients: Eight subjects who had screened positive for PGRN mutations (PGRN-positive) and who underwent volumetric magnetic resonance imaging were identified. Subjects were then matched by clinical diagnosis to a group of 8 subjects with a pathological diagnosis of FTLD-U who had screened negative for PGRN mutations (PGRN-negative). All subjects were then age-matched and sex-matched to a control subject. Main Outcome Measures: Voxel-based morphometry was used to assess the patterns of gray matter atrophy in the PGRN-positive group compared with the PGRN-negative group and compared with controls. Results: The PGRN-positive group showed a widespread and severe pattern of gray matter loss predominantly affecting the frontal, temporal, and parietal lobes. The PGRN-negative group showed a less severe pattern of gray matter loss restricted mainly to the temporal and frontal lobes. On direct comparison, the PGRN-positive group showed greater gray matter loss in the frontal and parietal lobes compared with the PGRN-negative group. Conclusion: Findings from this study suggest that PGRN mutations may be associated with a specific and severe pattern of cerebral atrophy in subjects with FTLD-U.