Possible Role of a Missense Mutation of p.P167S on NOTCH3 Gene Associated with Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy

Genetic spectrum of NOTCH3 and clinical phenotype of CADASIL patients in different populations

Introduction

Cerebral autosomal‐dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a relatively common cerebral small vessel disease. NOTCH3 has been identified as the causative gene of CADASIL. Clinical variability and genetic heterogeneity were observed in CADASIL patients and need to be further clarified.

Aims

The aim of the study was to clarify genetic spectrum of NOTCH3 and clinical phenotype of CADASIL patients.

Methods

Suspected CADASIL patients were collected by our center between 2016 and 2021. Whole exome sequencing was performed to screen NOTCH3 mutations of these patients. Genetic and clinical data of CADASIL patients from previous studies were also analyzed. Studies between 1998 and 2021 that reported more than 9 pedigrees with detailed genetic data or clinical data were included. After excluding patients carrying cysteine‐sparing mutations, genetic data of 855 Asian pedigrees (433 Chinese; 226 Japanese, and 196 Korean) and 546 Caucasian pedigrees, in a total of 1401 CADASIL pedigrees were involved in mapping mutation spectrum. Clinical data of 901 Asian patients (476 Chinese patients, 217 Japanese patients, and 208 Korean patients) and 720 Caucasian patients, in a total of 1621 patients were analyzed and compared between different populations.

Results

Two novel mutations (c.400T>C, p.Cys134Arg; c.1511G>A, p.Cys504Tyr) and 24 known cysteine‐affecting variants were identified in 36 pedigrees. Genetic spectrums of Asians (Chinese, Japanese, and Korean) and Caucasians were clarified, p.R544C and p.R607C were the most common mutations in Asians while p.R1006C and p.R141C in Caucasians. For clinical features, Asians were more likely to develop symptoms of TIA or ischemic stroke (p < 0.0001) and cognitive impairment (p < 0.0001). Nevertheless, Caucasians had a higher tendency to present migraine (p < 0.0001) and psychiatric disturbance (p < 0.0001). The involvement of temporal pole was more likely to happen in Caucasians (p < 0.0001).

Conclusion

The findings help to better understand the clinical variability and genetic heterogeneity of CADASIL.

Mutation spectrum and genotype-phenotype correlations in 157 Korean CADASIL patients: a multicenter study

CADASIL is an inherited disease caused by mutations in the NOTCH3 gene. We aimed to investigate the mutation and clinical spectrum, and genotype-phenotype correlations of Korean CADASIL patients. Samples from 492 clinically suspicious patients were collected from four hospitals. Sanger sequencing was performed to screen exons 2 to 25 of the NOTCH3 gene and variants of unknown significance (VUS) were analyzed using the ACMG guidelines. The medical records and MRI data were received from each hospital, for comprehensive analysis of genotype-phenotype correlations. Previously reported NOTCH3 variants were most commonly detected in exon 11 whereas exon 4 was the most common in European studies. The variants were detected equally between the EGFr domains 1-6 and 7-34, which was different from EGFr 1-6 predominant European studies. The average age-of-onset of patients with EGFr 1-6 variants were 4.81 ± 1.95 years younger than patients with EGFr 7-34 variants. Overall, it took Korean patients 51.2 ± 10 years longer to develop CADASIL in comparison to European patients. The most common mutation was p.R544C, which was associated with a later onset of stroke and a significant time-to-event curve difference. We verified four atypical phenotypes of p.R544C that had been reported in previous studies. Eight novel variants in 15 patients were detected but remained a VUS based on the ACMG criteria. This study reported a different EGFr distribution of Korean patients in comparison to European patients and its correlation with a later age-of-onset. An association between a later onset of stroke/TIA and p.R544C was observed.

CADASIL vs. Multiple Sclerosis: Is It Misdiagnosis or Concomitant? A Case Series

Introduction: Cerebral autosomal dominant arteriopathy and subcortical infarct leukoencephalopathy (CADASIL) is the most common form of hereditary stroke caused by a mutation in the NOTCH3 gene located on the short arm of chromosome 19. A small number of published reports describe CADASIL patients who were initially diagnosed as multiple sclerosis. Although it was previously indicated that there was no association between NOTCH3 mutations and multiple sclerosis, the involvement of autoimmune mechanisms among patients with CADASIL has been hypothesized.

Case Presentation: Case 1 is a middle-aged woman with initial diagnoses of multiple sclerosis (MS) and myelitis that continued to progress despite treatment with disease-modifying agents. She had occasional migraines, transient blurred vision, and multiple lacunar infarcts. She continued treatment for about 15 years with no significant alleviation and progressive changes on brain MRI; genetic testing was ordered which showed NOTCH3 mutation, and diagnosis was changed to CADASIL with subsequent revision of treatment course. However, the presence of myelitis in this patient is unusual and may raise the question of a concurrent autoimmune process. Case 2 is a woman presenting with vertigo and paresthesia and diagnosed with MS based on an initial brain MRI showing biventricular white matter hyperintensities; however, she was not started on any disease-modifying agents. Her symptoms were reevaluated by a neurologist, and genetic testing was performed for NOTCH 3. Case 3 is a young woman with a history of migraines who initially presented with numbness and gait ataxia which later progressed to speech difficulty and memory loss. A diagnosis of MS was established which was later changed to CADASIL.

Conclusion: Since CADASIL is a rare disease, it is imperative to raise awareness of its unique clinical condition as well as variation in its clinical presentations. It is crucial that the overlapping symptoms between MS and CADASIL be thoroughly examined to avoid misdiagnosis and treatment complications. The involvement of autoimmune mechanisms in CADASIL and the role of NOTCH3 gene mutations in provoking an autoimmune process should be further investigated.

Clinical Features of 4 Novel NOTCH3 Mutations of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy in China

Background

This study aimed to identify NOTCH3 mutations and describe the genetic and clinical features and magnetic resonance imaging results in 11 unrelated patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) from Henan province in China.

Material/Methods

NOTCH3 was directly sequenced in 11 unrelated patients of Chinese descent. The clinical presentations and magnetic resonance imaging features were retrospectively analyzed in the 11 index patients with a definite diagnosis.

Results

Seven different mutations were identified in 11 unrelated patients, including 4 novel mutations (p.P167S, p.P652S, p.C709R, and p.R1100H) in China and 3 reported mutations (p.C117R, p.R578C, and p.R607C). Four novel mutations (p.P167S, p.P652S, p.C709R, and p.R1100H) were predicted to be probably pathogenic using an online pathogenicity prediction program through comprehensive analysis. Clinical presentations in symptomatic patients included stroke, cognitive decline, psychiatric disturbances, and migraine. Multiple lacunars infarcts and leukoaraiosis were detected on MRI in most symptomatic patients, while white-matter lesions were identified in the temporal pole or the external capsule in all affected patients.

Conclusions

The mutation spectrum of CADASIL patients from Henan province in China displayed some differences from that of those reported previously. DNA sequencing was used to diagnose all 11 patients as having CADASIL, and we found 4 novel mutations. The present results further contribute to the enrichment of NOTCH3 mutation databases.