A Novel NOTCH3 Gene Mutation in a Polish CADASIL Family

Unveiling a Neurological Enigma: Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL) Presenting With Facial Palsy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an uncommon genetic disorder that affects small blood vessels in the brain. It leads to neurological symptoms, disability-adjusted life years, and difficult emotional and physical situations for patients and their families. As unusual brain symptoms appear, it becomes important to understand the different clinical manifestations of CADASIL. Our case report and review examine several cases to demonstrate different presentations and management strategies of CADASIL. A 52-year-old male with a family history of strokes at a young age from his father and paternal grandfather presented to a neurology clinic for left facial droop and drooling. Brain magnetic resonance imaging showed extensive periventricular and subcortical white matter disease, including the external capsule and subcortical white matter of the temporal lobe. Findings were suggestive of small vessel vasculopathy. A cerebral angiogram showed that all large extra- and intracranial vessels were patent without evidence of aneurysm formation. There was no obvious evidence of beading of the distal intracranial vessels. Cerebrospinal fluid studies were normal. The NOTCH3 mutation was sent to test for CADASIL, which came back positive. The patient was started on aspirin (81 mg) and atorvastatin (20 mg) daily. The patient was counseled on the possibility of having an ischemic or hemorrhagic stroke. Aspirin and atorvastatin were continued, a neuropsychological evaluation was ordered, and CADASIL genetic counseling and testing were offered to him and his children. Over several years, patients developed several strokes and seizures due to infarcts. He also developed intraparenchymal hemorrhage complicated by dysphagia, requiring a feeding tube. Due to his severe physical debility, he was discharged to a nursing home for rehabilitation, where he did not improve with therapy and remained bedbound. He was discharged and sent home with his family. CADASIL can present as a diagnostic challenge due to its common presentation with migraines, transient ischemic attacks, and strokes, with or without risk factors. This unique presentation of CADASIL with facial palsy highlights the importance of emerging atypical presentations and the need for a detailed history of neuroimaging, family history, and personal history of neurovascular events. By accurately diagnosing the condition, patients and families can be counseled on the disease course and genetics. Management requires a multidisciplinary approach with neurology, genetic counseling, physical therapy, psychology, and psychiatry if depression or anxiety is present, with the aim of improving the patient's quality of life.

Case report: Mild leukoencephalopathy caused by a new mutation of NOTCH3 gene

BACKGROUND

Cerebral autosomal dominant arteriosis with subcortical infarction and leukoencephalopathy (CADASIL) is a single-gene small-vessel disease of the brain characterized by migraine, recurrent ischemic stroke, psychiatric disorders, progressive cognitive decline, and occasional intracerebral hemorrhage.[1]NOTCH3 was identified as a pathogenic gene for CADASIL.[2] The NOTCH3 gene encodes a membrane-bound receptor protein, and to date, several different NOTCH3 gene mutations have been identified.[3] Here, we report a case of CADASIL with a heterozygous mutation c.931T > G (thymine > guanine) on the exon region of the NOTCH3 gene, resulting in an amino acid change p.C311G (cysteine > glycine).

CASE REPORT

We report a case of a female patient with CADASIL whose genetic sequencing revealed a mutation in the NOTCH3 gene. However, this patient did not exhibit any of the typical clinical findings of CADASIL but the patient's cerebral magnetic resonance imaging was consistent with the characteristic findings of CADASIL.

CONCLUSIONS

This case reminds us that mutations caused by different mutation sites present different clinical symptoms.

Influence of different spectra of NOTCH3 variants on the clinical phenotype of CADASIL - experience from Slovakia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary vascular disorder causing ischaemic attacks and strokes in middle-aged adults. Though the clinical spectrum includes some typical symptoms, recognition of the disease, especially at an earlier stage, is very difficult because of the highly variable manifestation and incomplete clinical picture. Characteristic brain MRI findings and the presence of pathogenic variants in the NOTCH3 gene are fundamental for CADASIL diagnosis. In this paper, we provide the first comprehensive report on CADASIL patients from Slovakia. Altogether, we identified 23 different pathogenic variants in 35 unrelated families. In our cohort of patients with clinical suspicion of CADASIL, we found a causal genetic defect and confirmed the diagnosis in 10.2% of cases. We present the case reports with up-to-date unpublished NOTCH3 variants and describe their phenotype-genotype correlation: p.(Cys65Phe), p.(Pro86Leu/Ser502Phe), p.(Arg156*), p.(Cys408Arg), p.(Tyr423Cys), p.(Asp1720His), and p.(Asp1893Thrfs*13). The most frequently described location for pathogenic variants was in exon 4, whereas the most common single variant was p.Arg1076Cys in exon 20. Based on the results of our study, we propose a re-evaluation of the criteria for the selection of patients suitable for NOTCH3 gene analysis. We hereby state that the currently used protocol of a high score requirement is not ideal for assessing molecular analysis, and it will be desirable to be less strict in criteria for genetic testing.

A case of CADASIL caused by NOTCH3 c.512_605delinsA heterozygous mutation

BACKGROUND

Autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebrovascular disease closely related to the NOTCH3 gene. More than 200 mutations in this gene have been reported to be associated with this disease.

METHODS

The NOTCH3 gene from CADASIL patient was screened for mutations by whole-exome sequencing (WES). PCR amplification and direct Sanger sequencing were used to verify the suspicious gene mutation sites detected by WES.

RESULTS

We performed second-generation sequencing on a sample of the patient's genome and found a heterozygous deletion-insertion mutation c.512_605delinsA in exon 4 of NOTCH3, which resulted in amino acid changes p.G171_A202delinsE. This variation was confirmed by the direct Sanger sequencing. It may be rated as a CADASIL clinical variation.

CONCLUSION

Discovery of this mutation site provides an important theoretical basis for specific gene-based diagnosis and treatment of CADASIL.

Nidogen-2 Maintains the Contractile Phenotype of Vascular Smooth Muscle Cells and Prevents Neointima Formation via Bridging Jagged1-Notch3 Signaling

Background: How the extracellular matrix (ECM) microenvironment modulates the contractile phenotype of vascular smooth muscle cells (VSMCs) and confers vascular homeostasis remains elusive. Methods: To explore the key ECM proteins in the maintenance of the contractile phenotype of VSMCs, we applied protein-protein interaction (PPI) network analysis to explore novel ECM proteins associated with the VSMC phenotype. By combining in vitro and in vivo genetic mice vascular injury model, we identified nidogen-2, a basement membrane (BM) glycoprotein, as a key ECM protein for maintenance of vascular smooth muscle cell identity. Results: We collected a VSMC phenotype-related gene dataset (VSMCPRG dataset) by using Gene Ontology (GO) annotation combined with a literature search. A computational analysis of protein-protein interactions between ECM protein genes and the genes from the VSMCPRG dataset revealed the candidate gene nidogen-2, a BM glycoprotein involved in regulation of the VSMC phenotype. Indeed, nidogen-2-deficient VSMCs exhibited loss of contractile phenotype in vitro, and compared with wild-type (WT) mice, nidogen-2^-/- mice showed aggravated post-wire injury neointima formation of carotid arteries. Further bioinformatics analysis, co-immunoprecipitation assays and luciferase assays revealed that nidogen-2 specifically interacted with Jagged1, a conventional Notch ligand. Nidogen-2 maintained the VSMC contractile phenotype via Jagged1-Notch3 signaling but not Notch1 or Notch2 signaling. Notably, nidogen-2 enhanced Jagged1 and Notch3 interaction and subsequent Notch3 activation. Reciprocally, Jagged1 and Notch3 interaction, signaling activation, and Jagged1-triggered VSMC differentiation were significantly repressed in nidogen-2-deficient VSMCs. In accordance, the suppressive effect of Jagged1 overexpression on neointima formation was attenuated in nidogen-2^-/- mice compared to wild-type mice. Conclusions: Nidogen-2 maintains the contractile phenotype of VSMCs through Jagged1-Notch3 signaling in vitro and in vivo. Nidogen-2 is required for Jagged1-Notch3 signaling.