BACKGROUND AND PURPOSE: Previous studies have shown that diffusion tensor imaging suggests a diffuse loss of white matter integrity in people with white matter hyperintensities or lacunes. The purpose of this study was to investigate whether the presence of cerebral microbleeds and their distribution are related to the integrity of white matter microstructures. MATERIALS AND METHODS: The study comprised 982 participants who underwent brain MR imaging to determine microbleed status. The cross-sectional relation between microbleeds and the microstructural integrity of the white matter was assessed by 2 statistical methods: a multilinear regression model based on the average DTI parameters of normal-appearing white matter and Tract-Based Spatial Statistics analysis, a tract-based voxelwise analysis. Fiber tractography was used to spatially describe the microstructural abnormalities along WM tracts containing a cerebral microbleed. RESULTS: The presence of cerebral microbleeds was associated with lower mean fractional anisotropy and higher mean diffusivity, axial diffusivity, and radial diffusivity, and the association remained when cardiovascular risk factors and cerebral small-vessel disease markers were further adjusted. Tract-Based Spatial Statistics analysis indicated strictly lobar cerebral microbleeds associated with lower fractional anisotropy, higher mean diffusivity, and higher radial diffusivity in the internal capsule and corpus callosum after adjusting other cerebral small-vessel disease markers, while only a few voxels remained associated with deep cerebral microbleeds. Diffusion abnormalities gradients along WM tracts containing a cerebral microbleed were not found in fiber tractography analysis. CONCLUSIONS: Cerebral microbleeds are associated with widely distributed changes in white matter, despite their focal appearance on SWI. ABBREVIATIONS: CMB ¼ cerebral microbleed; CSVD ¼ cerebral small vessel disease; MD ¼ mean diffusivity; FA ¼ fractional anisotropy; NAWM ¼ normalappearing white matter; WMH ¼ white matter hyperintensity; TBSS ¼ Tract-Based Spatial Statistics A ccording to recent evidence, cerebral small vessel disease (CSVD) was found to have focal brain parenchymal lesions not only visible on brain MR imaging but also related to a wider range of white matter microstructural injury. 1-3 These studies mainly focused on ischemic lesions related to CSVD, such as lacunes or white matter hyperintensities. Cerebral microbleeds (CMBs), characterized as focal hemosiderin deposits without remarkable brain tissue loss in

Background and Purpose: Researches on rare variants of NOTCH3 in the general Chinese population are lacking. This study aims to describe the spectrum of rare NOTCH3 variants by whole-exome sequencing in a Chinese community-based cohort and to investigate the association between rare NOTCH3 variants and age-related cerebral small vessel disease. Methods: The cross-sectional study comprised 1065 participants who underwent whole-exome sequencing and brain magnetic resonance imaging. NOTCH3 variants with minor allele frequency<1% in all 4 public population databases (1000 Genomes, ESP6500siv2_ALL, GnomAD_ALL, and GnomAD_EAS) were defined as rare variants. Multivariable linear and logistic regressions were used to investigate the associations between rare NOTCH3 variants and volume of white matter hyperintensities and cerebral small vessel disease burden. Clinical and imaging characteristics of rare NOTCH3 variant carriers were summarized. Results: Sixty-five rare NOTCH3 variants were identified in 147 of 1065 (13.8%) participants, including 57 missense single nucleotide polymorphisms (SNPs), 5 SNPs in splice branching sites, and 3 frameshift deletions. A significantly higher volume of white matter hyperintensities and heavier burden of cerebral small vessel disease was found in carriers of rare NOTCH3 EGFr (epidermal growth factor-like repeats)-involving variants, but not in carriers of EGFr-sparing variants. The carrying rate of rare EGFr-involving NOTCH3 variants in participants with dementia or stroke was significantly higher than those without dementia or stroke (12.4% versus 6.6%, P =0.041). Magnetic resonance imaging signs suggestive of CADASIL were found in 3.4% (5/145) rare EGFr cysteine-sparing NOTCH3 variant carriers but not in 2 cysteine-altering NOTCH3 variant carriers. Conclusions: Carriers of rare NOTCH3 variants involving the EGFr domain may be genetically predisposed to age-related cerebral small vessel disease in the general Chinese population.