Three-tiered EGFr domain risk stratification for individualized NOTCH3-small vessel disease prediction

Hack, R.J.; Gravesteijn, G.; Cerfontaine, M.N.; Santcroos, M.A.; Gatti, L.; Kopczak, A.; ... ; Oberstein, S.A.J.L. (2022)

Article / Letter to editor

Cysteine-altering missense variants (NOTCH3^cys) in one of the 34 epidermal growth-factor-like repeat (EGFr) domains of the NOTCH3 protein are the cause of NOTCH3-associated small vessel disease (NOTCH3-SVD). NOTCH3-SVD is highly variable, ranging from cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) at the severe end of the spectrum to non-penetrance. The strongest known NOTCH3-SVD modifier is NOTCH3^cys variant position: NOTCH3^cys variants located in EGFr domains 1–6 are associated with a more severe phenotype than NOTCH3^cys variants located in EGFr domains 7–34. The objective of this study was to further improve NOTCH3-SVD genotype-based risk prediction by using relative differences in NOTCH3^cys variant frequencies between large CADASIL and population cohorts as a starting point.

Scientific CADASIL literature, cohorts and population databases were queried for NOTCH3^cys variants. For each EGFr domain, the relative difference in NOTCH3^cys variant frequency (NVFOR) was calculated using genotypes of 2574 CADASIL patients and 1647 individuals from population databases. Based on NVFOR cut-off values, EGFr domains were classified as either low (LR-EGFr), medium (MR-EGFr) or high risk (HR-EGFr). The clinical relevance of this new three-tiered EGFr risk classification was cross-sectionally validated by comparing SVD imaging markers and clinical outcomes between EGFr risk categories using a genotype-phenotype data set of 434 CADASIL patients and 1003 NOTCH3^cys positive community-dwelling individuals.

CADASIL patients and community-dwelling individuals harboured 379 unique NOTCH3^cys variants. Nine EGFr domains were classified as an HR-EGFr, which included EGFr domains 1–6, but additionally also EGFr domains 8, 11 and 26. Ten EGFr domains were classified as MR-EGFr and 11 as LR-EGFr. In the population genotype–phenotype data set, HR-EGFr individuals had the highest risk of stroke [odds ratio (OR) = 10.81, 95% confidence interval (CI): 5.46–21.37], followed by MR-EGFr individuals (OR = 1.81, 95% CI: 0.84–3.88) and LR-EGFr individuals (OR = 1 [reference]). MR-EGFr individuals had a significantly higher normalized white matter hyperintensity volume (nWMHv; P = 0.005) and peak width of skeletonized mean diffusivity (PSMD; P = 0.035) than LR-EGFr individuals. In the CADASIL genotype–phenotype data set, HR-EGFr domains 8, 11 and 26 patients had a significantly higher risk of stroke (P = 0.002), disability (P = 0.041), nWMHv (P = 1.8 × 10⁻⁸), PSMD (P = 2.6 × 10⁻⁸) and lacune volume (P = 0.006) than MR-EGFr patients. SVD imaging marker load and clinical outcomes were similar between HR-EGFr 1–6 patients and HR-EGFr 8, 11 and 26 patients. NVFOR was significantly associated with vascular NOTCH3 aggregation load (P = 0.006), but not with NOTCH3 signalling activity (P = 0.88).

In conclusion, we identified three clinically distinct NOTCH3-SVD EGFr risk categories based on NFVOR cut-off values, and identified three additional HR-EGFr domains located outside of EGFr domains 1–6. This EGFr risk classification will provide an important key to individualized NOTCH3-SVD disease prediction.

• NOTCH3
• SVD
• CADASIL
• risk classification
• EGFr domain

• All authors: Hack, R.J.; Gravesteijn, G.; Cerfontaine, M.N.; Santcroos, M.A.; Gatti, L.; Kopczak, A.; Bersano, A.; Duering, M.; Rutten, J.W.; Oberstein, S.A.J.L.
• Date: 2022-12-20
• Journal: Brain
• Volume: 146
• Issue: 7
• Pages: 2913 - 2927
• DOI: doi:10.1093/brain/awac486
• Link: https://academic.oup.com/brain/article/146/7/2913/6940341