Effect of NOTCH3 EGFr Group, Sex, and Cardiovascular Risk Factors on CADASIL Clinical and Neuroimaging Outcomes

Abstract

Background: A retrospective study has shown that EGFr (epidermal growth factor-like repeat) group in the NOTCH3 gene is an important cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) disease modifier of age at first stroke and white matter hyperintensity (WMH) volume. No study has yet assessed the effect of other known CADASIL modifiers, that is, cardiovascular risk factors and sex, in the context of NOTCH3 EGFr group. In this study, we determined the relative disease-modifying effects of NOTCH3 EGFr group, sex and cardiovascular risk factor on disease severity in the first genotype-driven, large prospective CADASIL cohort study, using a comprehensive battery of CADASIL clinical outcomes and neuroimaging markers.

Methods: Patients with CADASIL participated in a single-center, prospective cohort study (DiViNAS [Disease Variability in NOTCH3 Associated Small Vessel Disease]) between 2017 and 2020. The study protocol included a clinical assessment, neuropsychological test battery and brain magnetic resonance imaging on a single research day. Multivariable linear, logistic and Cox regression models were used to cross-sectionally assess the effect of CADASIL modifiers on clinical severity (stroke, disability, processing speed) and neuroimaging markers (WMH volume, peak width of skeletonized mean diffusivity, lacune volume, brain volume, cerebral microbleed count).

Results: Two hundred patients with CADASIL participated, of which 103 harbored a NOTCH3 EGFr 1-6 variant and 97 an EGFr 7-34 variant. NOTCH3 EGFr 1-6 group was the most important modifier of age at first stroke (hazard ratio, 2.45 [95% CI, 1.39-4.31]; P=0.002), lacune volume (odds ratio, 4.31 [95% CI, 2.31-8.04]; P=4.0×10^-6), WMH volume (B=0.81 [95% CI, 0.60-1.02]; P=1.1×10^-12), and peak width of skeletonized mean diffusivity (B=0.65 [95% CI, 0.44-0.87]; P=1.6×10^-8). EGFr 1-6 patients had a significantly higher WMH volume in the anterior temporal lobes and superior frontal gyri and a higher burden of enlarged perivascular spaces. After NOTCH3 EGFr group, male sex and hypertension were the next most important modifiers of clinical outcomes and neuroimaging markers.

Conclusions: NOTCH3 EGFr group is the most important CADASIL disease modifier not only for age at first stroke and WMH volume but also strikingly so for a whole battery of clinically relevant disease measures such as lacune volume and peak width of skeletonized mean diffusivity. NOTCH3 EGFr group is followed in importance by sex, hypertension, diabetes, and smoking.

Keywords: CADASIL; hypertension; mutation; neuroimaging; risk factors; sex; white matter.

Figure 1.

Cysteine altering NOTCH3 variants (NOTCH3^cys) located in epidermal growth factor-like repeat (EGFr) domains 1–6 are associated with an increased risk of stroke and lower survival compared to EGFr 7–34 NOTCH3^cys variants. Kaplan-Meier plots showing that EGFr 1–6 patients have a significantly earlier onset of stroke (median 58 vs >73 y; P_LR=8.1×10^-4; A) and transient ischemic attack (TIA; median 57 vs 72 y; P_LR=0.019; B), than EGFr 7–34 patients. Affected parents of EGFr 1–6 patients have an earlier onset of stroke (median 58 vs 68 y; P_LR=0.010; C) and a lower life expectancy (median 69 y vs 74 y; P_LR=0.021; D), than affected parents of EGFr 7–34 patients. The affected parent of 13 patients with a NOTCH3^cys EGFr 7–34 variant could not be discerned as neither parent had obvious cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)–associated signs or symptoms. DiViNAS indicates Disease Variability in NOTCH3 Associated Small Vessel Disease.

Figure 2.

Cysteine altering NOTCH3 variants (NOTCH3^cys) located in EGFr (epidermal growth factor-like repeat) domains 1–6 are associated with a higher white matter hyperintensity volume, peak width of skeletonized mean diffusivity, lacune volume, and brain parenchymal fraction compared to EGFr 7–34 NOTCH3^cys variants. Scatterplots showing that EGFr 1–6 patients have a significantly higher normalized white matter hyperintensity volume (nWMHv; B=0.80 [95% CI, 0.60–1.01]; P=7.6×10^-13; A), peak width of skeletonized mean diffusivity (PSMD; B=0.65 [95% CI, 0.43–0.86]; P=2.2×10^-8; B), normalized lacune volume (nLV; odds ratio [OR], 3.74 [95% CI, 2.07–6.92]; P=1.8×10^-5; C), and brain parenchymal fraction (BPF; B=0.24 [95% CI, 0.01–0.48]; P=0.045; D) than EGFr 7–34 patients. (E) There were no significant difference in cerebral microbleed count (total and per region). The odds ratio is shown for EGFr 1–6 patients compared to EGFr 7–34 patients (reference group: OR=1).

Figure 3.

Cysteine altering NOTCH3 variants (NOTCH3^cys) located in epidermal growth factor-like repeat (EGFr) domains 1–6 are associated with a higher burden of white matter hyperintensity volume and enlarged perivascular spaces in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)–specific regions, that is, anterior temporal lobes and superior frontal gyri, than EGFr 7–34 NOTCH3^cys variants. A and B, EGFr 1–6 patients have a significantly higher normalized white matter hyperintensity volume (nWMHv) in the anterior temporal lobes (ATL; B=1.00 [95% CI, 0.77–1.23]; P=5.8×10^-15) and superior frontal gyri (SFG; B=0.83 [95% CI, 0.59–1.07]; P=1.6×10^-10) than EGFr 7–34 patients. C and D, After adjustment for total nWMHv, this remained significant for nWMHv in the ATL (B=0.26 [95% CI, 0.11–0.42]; P=9.7×10^-4; C) and was borderline significant for SFG (B=0.18 [95% CI, −0.02 to 0.37]; P=0.072). E, EGFr 1–6 patients have a significantly higher burden of enlarged perivascular spaces than EGFr 7–34 patients in the ATL (P=8.3×10^-7) and subinsular regions (P=0.006), but not in the basal ganglia (P=0.10) or the white matter (P=0.49). The odds ratio is shown for EGFr 1–6 patients compared to EGFr 7–34 patients (reference group: odds ratio, 1).

Figure 4.

Representative brain magnetic resonance imaging (MRI) of an EGFr (epidermal growth factor-like repeat) 1–6 and an EGFr 7–34 patient with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A, Brain MRI FLAIR images of an EGFr 1–6 patient aged in his late 40s showing large confluent white matter hyperintensity (WMH) and a high burden of enlarged perivascular spaces (ePVS) in the anterior temporal lobes (yellow arrow), a high burden of ePVS in the subinsular regions (red arrow), and confluent WMH in the superior frontal gyri (blue arrow). B, Brain MRI fluid-attenuated inversion recovery images of an EGFr 7–34 patient aged in his early 60s with a similar total WMHv, but with no WMH in anterior temporal lobes, only small punctate foci of WMH in superior frontal gyri, and very low burden of ePVS in anterior temporal lobes and subinsular regions.

Figure 5.

Effect of cysteine altering missense NOTCH3 variant (NOTCH3^cys) EGFr (epidermal growth factor-like repeat) group, sex, and cardiovascular risk factors on cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) disease severity. Forest plots showing the effect of EGFr group, sex and cardiovascular risk factors on clinical outcomes (A and B) and SVD imaging markers (C–F) in multivariable models expressed as hazard ratios, odds ratios and as regression coefficients. All dependent and independent continuous variables were standardized by dividing their value by their SD. DM indicates diabetes; HC, hypercholesterolemia; HT, hypertension; mRS, modified Rankin Scale; nWMHv, normalized white matter hyperintensity volume; and PSMD, peak width of the skeletonized mean diffusivity. *Hazard ratio (HR)/odds ratio (OR)/B is shown per SD of the variable. †HR/OR/B is shown for the presence of variable. ‡=normalized lacune volume was stratified in 4 categories (0; 0–0.005; 0.005–0.025; >0.025).