White matter hyperintensities characterize monogenic frontotemporal dementia with granulin mutations.

No study but one has suggested the presence of white matter hyperintensities (WMHs) in frontotemporal dementia (FTD), limited to 4 cases carrying pathogenic Granulin (GRN) gene mutations. We investigated the presence of WMHs in a cohort of 14 FTD patients with pathogenic GRN mutations (GRN+), 28 patients without GRN mutations (GRN-) and 18 healthy controls (HC). We further considered 11 asymptomatic GRN+ subjects and 11 young age-matched healthy controls (yHC). The WMH burden was automatically computed and a voxelwise-based analysis was carried out to explore the differences in WMH brain spatial distribution. FTD-GRN+ patients had increased total WMH burden than both HC (p < 0.001) and FTD-GRN-(p = 0.01) groups. WMHs were mainly localized in the right middle frontal and superior temporal gyri, in the left superior frontal in the left parietal gyri. No significant differences of WMH burden between asymptomatic GRN+ and yHC were observed. The presence of WMHs in cases of FTD may suggest a novel mechanism of GRN disease-related neurodegeneration, may be of help in the differential diagnosis, and in guiding genetic screening.