Pattern of Brain Parenchymal Damage Related to Cerebral Small Vessel Disease in Carriers of Rare NOTCH3 Variants.

BACKGROUND AND OBJECTIVES: Previous studies reported that carriers of rare NOTCH3 variants comprised more than 10% of the general population and are susceptible to a heavy overall burden of cerebral small vessel disease while the injury patterns remain uncovered. This study aimed to investigate the imaging features in relation to rare NOTCH3 variants and the interaction between cortical atrophy and white matter lesions from a longitudinal view, with respect to spatial and dynamic patterns. METHODS: As part of a community-based cohort, we included participants with complete whole-exome sequencing and brain MRI in the baseline analysis. All participants were invited for a 5-year follow-up MRI, and those who did not complete the follow-up were excluded from the longitudinal analysis. NOTCH3 variants with minor allele frequency <1% in all 4 public population databases were defined as rare variants. We used general linear models to compare the volume of white matter hyperintensity (WMH) volume and brain parenchymal fraction between rare NOTCH3 variant carriers and noncarriers. In addition, we compared the WMH probability map and vertex-wise cortex maps at a voxel/vertex-wise level. RESULTS: A total of 1,054 participants were included in baseline analysis (13.56% carried rare NOTCH3 variants), among whom 661 had a follow-up brain MRI (13.76% carried rare NOTCH3 variants). Rare NOTCH3 variant carriers had a heavier white matter hyperintensity burden (1.65 vs 0.85 mL, p = 0.025) and had more extensive WMH distributed in the periventricular areas. We also found that rare NOTCH3 variant carriers were susceptible to worse cortical atrophy (ß = -0.004, SE = 0.002, p = 0.057, adjusted for age and sex). Cortical atrophy of multiple regions in the frontal and parietal lobes was related to white matter hyperintensity progression. DISCUSSION: Individuals with rare NOTCH3 variants have a distinct pattern of brain parenchymal damage related to CSVD. Our findings uncover the important genetic predisposition in age-related cerebral small vessel disease in the general population.

Genetically predicted telomere length and multiple sclerosis.

BACKGROUND: Previous epidemiological studies have indicated a role for telomere length in multiple sclerosis (MS) severity and phenotype. However, these studies failed to establish the causality between telomere length and MS susceptibility. Hence, we performed two-sample Mendelian randomization (MR) analysis to explore the causal relationship between telomere length and MS susceptibility. METHODS: We used data of genetic variants associated with leukocyte telomere length as instrumental variables (IVs), which was identified from the largest and latest genome-wide association study (GWAS) from UK Biobank (UKB) with 472,174 participants. Summary data of MS was obtained from the International Multiple Sclerosis Genetics Consortium. We performed two-sample MR analyses using the inverse-variance weighted method as the primary approach. Other MR approaches, including the MR-Egger, the inverse variance weighted (multiplicative random effects), weighted median, simple median, weighted mode-based methods, and Causal Analysis Using Summary Effect estimates (CAUSE), were also conducted to detect the result robustness. RESULTS: The genetic liability to longer telomere length was associated with a higher risk of MS susceptibility (odds ratio [OR] per one-SD telomere length, 1.91; 95% confidence interval [CI], 1.48-2.47; P = 8.04 × 10-7). The results remained consistent across multiple sensitivity analyses. CONCLUSIONS: Our study supports the causal relationship between longer telomere length and increased risk of MS susceptibility.

Migraine and Ischemic Stroke: A Mendelian Randomization Study.

INTRODUCTION: Previous epidemiological studies have found an increased risk for ischemic stroke in patients with migraine; however, the evidence for a causal relationship between migraine and ischemic stroke is scarce. This study aims to explore the potential causal relationship between migraine and ischemic stroke and its subtypes [including large artery stroke (LAS), small vessel stroke (SVS), and cardioembolic stroke (CES)]. METHODS: We used data on genetic variants associated with migraine identified from a genome-wide association study (GWAS) meta-analysis among 889,018 European ancestries. Summary data for ischemic stroke and its subtypes were obtained from the MEGASTROKE consortium including up to 438,847 participants. We performed two-sample Mendelian randomization (MR) analyses using the inverse-variance-weighted method as the primary approach. The MR-Egger, weighted median, simple median, simple mode, and weighted mode methods were also conducted as sensitivity analyses to determine the robustness of our results. RESULTS: We failed to detect statistically significant associations between migraine and ischemic stroke (OR, 0.935; 95% CI 0.851-1.027; P = 0.159) and its subtypes (LAS: OR, 0.818; 95% CI 0.692-0.967; P = 0.018) (SVS: OR, 0.935; 95% CI 0.781-1.119; P = 0.460) (CES: OR, 1.015; 95% CI 0.867-1.189; P = 0.850). The results were consistent with the sensitivity analyses. CONCLUSIONS: By conducting a series of causal inference approaches, this study supports no causal effect of migraine on ischemic stroke and its subtypes.

Metabolic syndrome, intracranial arterial stenosis and cerebral small vessel disease in community-dwelling populations.

BACKGROUND AND PURPOSE: This study aimed to investigate the association of metabolic syndrome (MetS) with both intracranial atherosclerotic stenosis (ICAS) and imaging markers of cerebral small vessel disease (CSVD) in a community-based sample. METHODS: This study included 943 participants (aged 55.6±9.2 years, 36.1% male) from the community-based Shunyi cohort study. MetS was defined according to the joint interim criteria and quantified by the MetS severity Z-score. ICAS was evaluated by brain magnetic resonance angiography. The MRI markers of CSVD, including white matter hyperintensities (WMHs), lacunes, cerebral microbleeds (CMBs) and enlarged perivascular spaces (EPVS), were assessed. Multiple regression models were used to investigate the association of MetS severity Z-score with ICAS and these CSVD markers. RESULTS: We found that risk of ICAS (OR=1.75, 95% CI 1.39 to 2.21, p<0.001) increased consistently with MetS severity. MetS severity was significantly associated with higher risks of WMH volume (ß=0.11, 95% CI 0.01 to 0.20, p=0.02) and lacunes (OR=1.28, 95% CI 1.03 to 1.59, p=0.03) but not the presence of CMBs (OR=0.93, 95% CI 0.74 to 1.16, p=0.51) and PVS severity (EPVS in basal ganglia: OR=0.96, 95% CI 0.84 to 1.09, p=0.51 and EPVS in white matter: OR=1.09, 95% CI 0.96 to 1.23, p=0.21). CONCLUSIONS: Our findings suggest that WMH and lacunes share risk factors with atherosclerosis of the cerebral artery, whereas the impact of glucose and lipid metabolic disorder to CMB or EPVS might be weak.