Prevalence and clinical characteristics of stroke patients with p.R544C NOTCH3 mutation in Taiwan

Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

The Roles of NOTCH3 p.R544C and Thrombophilia Genes in Vietnamese Patients With Ischemic Stroke: Study Involving a Hierarchical Cluster Analysis

BACKGROUND

The etiology of ischemic stroke is multifactorial. Several gene mutations have been identified as leading causes of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary disease that causes stroke and other neurological symptoms.

OBJECTIVE

We aimed to identify the variants of NOTCH3 and thrombophilia genes, and their complex interactions with other factors.

METHODS

We conducted a hierarchical cluster analysis (HCA) on the data of 100 patients diagnosed with ischemic stroke. The variants of NOTCH3 and thrombophilia genes were identified by polymerase chain reaction with confronting 2-pair primers and real-time polymerase chain reaction. The overall preclinical characteristics, cumulative cutpoint values, and factors associated with these somatic mutations were analyzed in unidimensional and multidimensional scaling models.

RESULTS

We identified the following optimal cutpoints: creatinine, 83.67 (SD 9.19) µmol/L; age, 54 (SD 5) years; prothrombin (PT) time, 13.25 (SD 0.17) seconds; and international normalized ratio (INR), 1.02 (SD 0.03). Using the Nagelkerke method, cutpoint 50% values of the Glasgow Coma Scale score; modified Rankin scale score; and National Institutes of Health Stroke Scale scores at admission, after 24 hours, and at discharge were 12.77, 2.86 (SD 1.21), 9.83 (SD 2.85), 7.29 (SD 2.04), and 6.85 (SD 2.90), respectively.

CONCLUSIONS

The variants of MTHFR (C677T and A1298C) and NOTCH3 p.R544C may influence the stroke severity under specific conditions of PT, creatinine, INR, and BMI, with risk ratios of 4.8 (95% CI 1.53-15.04) and 3.13 (95% CI 1.60-6.11), respectively (Pfisher<.05). It is interesting that although there are many genes linked to increased atrial fibrillation risk, not all of them are associated with ischemic stroke risk. With the detection of stroke risk loci, more information can be gained on their impacts and interconnections, especially in young patients.

Prevalence, clinical characteristics, and risk factors of intracerebral haemorrhage in CADASIL: a case series and systematic review

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic form of stroke and is characterised by early onset stroke and dementia. Most strokes are lacunar ischaemic strokes, but intracerebral haemorrhage (ICH) has also been reported, although there are limited published data on its frequency and characteristics.

METHODS

A retrospective review of a prospectively recruited CADASIL register from the British National Referral clinic was performed to identify acute ICH cases and their characteristics. In addition, a systematic review of ICH in CADASIL was performed. MEDLINE (Pubmed), Embase, and Web of Science were searched for articles published from inception until 31/05/2023.

RESULTS

Ten cases of ICH were identified from the National clinic register of 516 symptomatic patients, giving an estimated point prevalence of 1.9%. An additional 119 cases were identified from the systematic review, comprising 129 cases and 142 ICH events in total. Including all identified cases, the mean age at onset of ICH was 56.6 ± 15.7 (SD) years, and 74 (57.4%) were male. ICH was the first manifestation of the disease in 32 patients (38.1%), and ICH recurrence occurred in 16 (12.4%). Most ICHs were subcortical, with the thalamus, 58 (40.8%), and basal ganglia, 34 (23.9%), being the commonest sites. Anticoagulation, but not antiplatelet agents, was associated with an increased risk of ICH (20.0% vs. 1.9%, p = 0.006).

CONCLUSIONS

ICH is a relatively rare manifestation of CADASIL, occurring in about 2% of symptomatic cases. Most of the haemorrhages occurred in the subcortical regions.

Modifiable vascular risk factors contribute to stroke in 1080 NOTCH3 R544C carriers in Taiwan Biobank

BACKGROUND AND AIM

Previous studies have suggested cardiovascular risk factors increase the risk of not only common sporadic stroke but also of stroke in patients with monogenic stroke disorders including CADASIL. We investigated the effects of the NOTCH3 Arg544Cys (R544C) variant and associated vascular risk factors on stroke in the Taiwanese population.

METHODS

This study was conducted using data from the Taiwan Biobank, consisting of at least 130,000 Han Chinese participants. The genotype was derived from customized genome-wide arrays for 650,000 to 750,000 single-nucleotide polymorphisms (SNPs). Individuals with NOTCH3 R544C were subsequently matched with noncarriers based on the propensity score at a 1:10 ratio by demographic and cardiovascular risk factors. The odds ratio (OR) for stroke or other phenotypes in NOTCH3 R544C carriers and matched noncarriers was then calculated. Univariate and multivariate regression analyses were performed on cardiovascular risk factors in NOTCH3 R544C carriers with and without stroke. The polygenic risk score (PRS) model, adopted from the UK Biobank, was then applied to evaluate the role of NOTCH3 R544C in stroke.

RESULTS

From the 114,282 participants with both genotype and questionnaire results, 1080 (0.95%) harbored the pathogenic NOTCH3 R544C variant. When compared to the matched controls (n = 10,800), the carriers presented with a history of stroke (OR: 2.52, 95% confidence interval (CI) (1.45, 4.37)), dementia (OR: 30.1, 95% CI (3.13, 289.43)), and sibling history of stroke (OR: 2.48, 95% CI (1.85, 3.34)) phenotypes. The risk of stroke increased with every 10-year increase in age (p = 0.006, Cochran-Mantel-Haenszel test). Among NOTCH3 R544C carriers, 16 (1.3%) of the 1080 carriers with a stroke history were older, male, and more likely to have hypertension, diabetes, dyslipidemia, and a family history of stroke. In the stepwise multivariate analysis, hypertension (OR: 11.28, 95% CI (3.54, 43.3)) and diabetes mellitus (OR: 4.10, 95% CI (1.31, 12.4)) were independently associated with stroke. Harboring the NOTCH3 R544C variant in the Taiwan Biobank is comparable with a 6.74 standard deviations increase in individual's polygenic risk score for stroke.

CONCLUSION

While the NOTCH3 R544C variant alone increased the risk of stroke, modifiable vascular risk factors also played a role in the occurrence of stroke in Taiwanese community-dwelling individuals carrying the NOTCH3 variant.

The cysteine-altering p.R544C variant in the NOTCH3 gene is a probable candidate for blood pressure and relevant traits in the Taiwan Biobank

BACKGROUND

The cysteine-altering variants in NOTCH3 have been suggested to be associated with stroke, dementia, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), where aberrant blood pressure levels represent the characteristics of these diseases. We aimed to assess whether the cysteine-altering p.Arg544Cys (p.R544C; rs201118034) variant and common single nucleotide variants (SNVs) in NOTCH3 could contribute to systolic and diastolic blood pressure and related phenotypes in the Taiwan Biobank.

METHODS

We employed a discovery sample of 68,925 individuals, an independent replication sample of 45,676 individuals, and a combined/total sample of 114,601 individuals; all from the Taiwan Biobank. Blood pressure, such as systolic and diastolic blood pressure, was measured for all participants. Association was evaluated using a general linear model, where results were considered statistically significant if the P value < 0.05 divided by the number of independent tests per model.

RESULTS

From our analysis, we identified and replicated three novel candidates for blood pressure that have not previously been reported: the cysteine-altering p.R544C variant for systolic blood pressure, the common SNV rs11669950 for diastolic blood pressure, and the common SNV rs4808235 for diastolic blood pressure. We also generalized two previously identified SNVs (i.e., rs10418305 and rs7408868) in NOTCH3 for blood pressure in European and non-Taiwanese East Asian populations to the Taiwanese population. Moreover, the participants with NOTCH3 p.R544C had an increased stroke frequency (P < 1.0 × 10-5) and a higher dementia frequency (P = 2.0 × 10-4) compared with the whole Taiwan Biobank population in the combined/total sample.

CONCLUSION

NOTCH3 is a strong candidate for a role in stroke, dementia, and CADASIL, which has previously been linked to blood pressure changes. While our preliminary study suggests that NOTCH3 p.R544C may influence blood pressure, stroke, and dementia in the Taiwan Biobank, replication in a well-powered external sample is required. This study also underlines considerable prospects of detecting novel genetic biomarkers in underrepresented worldwide populations.

Update on the Epidemiology, Pathogenesis, and Biomarkers of Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic disorder of the cerebral small blood vessels. It is caused by mutations in the NOTCH3 gene on chromosome 19, and more than 280 distinct pathogenic mutations have been reported to date. CADASIL was once considered a very rare disease with an estimated prevalence of 1.3-4.1 per 100,000 adults. However, recent large-scale genomic studies have revealed a high prevalence of pathogenic NOTCH3 variants among the general population, with the highest risk being among Asians. The disease severity and age at onset vary significantly even among individuals who carry the same NOTCH3 mutations. It is still unclear whether a significant genotype-phenotype correlation is present in CADASIL. The accumulation of granular osmiophilic material in the vasculature is a characteristic feature of CADASIL. However, the exact pathogenesis of CADASIL remains largely unclear despite various laboratory and clinical observations being made. Major hypotheses proposed so far have included aberrant NOTCH3 signaling, toxic aggregation, and abnormal matrisomes. Several characteristic features have been observed in the brain magnetic resonance images of patients with CADASIL, including subcortical lacunar lesions and white matter hyperintensities in the anterior temporal lobe or external capsule, which were useful in differentiating CADASIL from sporadic stroke in patients. The number of lacunes and the degree of brain atrophy were useful in predicting the clinical outcomes of patients with CADASIL. Several promising blood biomarkers have also recently been discovered for CADASIL, which require further research for validation.

Clinical Characteristics and Gene Mutation Analysis of Poststroke Epilepsy

Epilepsy is one of the most common brain disorders worldwide. Poststroke epilepsy (PSE) affects functional retrieval after stroke and brings considerable social values. A stroke occurs when the blood circulation to the brain fails, causing speech difficulties, memory loss, and paralysis. An electroencephalogram (EEG) is a tool that may detect anomalies in brain electrical activity, including those induced by a stroke. Using EEG data to determine the electrical action in the brains of stroke patients is an effort to measure therapy. Hence in this paper, deep learning assisted gene mutation analysis (DL-GMA) was utilized for classifying poststroke epilepsy in patients. This study suggested a model categorizing poststroke patients based on EEG signals that utilized wavelet, long short-term memory (LSTM), and convolutional neural networks (CNN). Gene mutation analysis can help determine the cause of an individual's epilepsy, leading to an accurate diagnosis and the best probable medical management. The test outcomes show the viability of noninvasive approaches that quickly evaluate brain waves to monitor and detect daily stroke diseases. The simulation outcomes demonstrate that the proposed GL-GMA achieves a high accuracy ratio of 98.3%, a prediction ratio of 97.8%, a precision ratio of 96.5%, and a recall ratio of 95.6% and decreases the error rate 10.3% compared to other existing methods.

Comparison of clinical and neuroimaging features between NOTCH3 mutations and nongenetic spontaneous intracerebral haemorrhage

BACKGROUND

The NOTCH3 mutation is a common cause of hereditary cerebral small vessel disease (CSVD) and may be a cause of spontaneous intracerebral haemorrhage (ICH). We aimed to investigate the clinical/imaging features for identifying the NOTCH3 mutations related ICH.

METHODS

The study was based on a cohort of 749 CSVD patients in Taiwan who received next-generation sequencing of CSVD genes including NOTCH3. Patients with history of ICH (n=206) were included for analysis. The CSVD neuroimaging markers were compared between the patients with NOTCH3 and without known genetic mutations.

RESULTS

After excluding the patients with other causes of ICH (structural lesions, systemic/medication-related, or amyloid angiopathy) and those without neuroimaging, 45 NOTCH3 mutation patients and 109 nongenetic ICH patients were included. The NOTCH3 mutation patients were more likely to have thalamic haemorrhage, a family history of stroke, and more severe CSVD neuroimaging markers. A five-point NOTCH3-ICH score was constructed and consisted of: history of stroke in siblings, thalamic haemorrhage, any deep nuclei lacunae, any hippocampal cerebral microbleed (CMB), and a thalamic CMB >5 (one point for each). A score ≥2 had a sensitivity of 88.9% and a specificity of 64.2% in identifying the NOTCH3 mutation. The NOTCH3 mutation patients had a higher risk of recurrent stroke (9.1 vs. 4.5 per 100 person-years; log-rank p = 0.03) during follow-up.

CONCLUSION

The patients with NOTCH3 mutation-related ICH had a higher burden of CMB in the hippocampus/thalamus and a higher recurrent stroke risk. The NOTCH3-ICH score may assist identifying genetic causes of ICH.

Reduced macular vessel density and inner retinal thickness correlate with the severity of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), caused by mutations in NOTCH3, is the most common cause of hereditary cerebral small vessel disease. Whether it will involve systemic vasculopathy such as retinal vessel remains unknown. Optical coherence tomography angiography (OCT-A) is a noninvasive technique for visualising retinal blood flow. We analysed vessel density and retinal thickness in patients with CADASIL and investigated their correlations with disease severity.

METHODS

This prospective study enrolled 35 patients with CADASIL (59 eyes) and 35 healthy controls (54 eyes). OCT-A was used to measure the vessel density of the macular region and the thickness of retinal layers. Patients with CADASIL were divided into stroke (n = 20) and nonstroke (n = 15) subgroups and underwent cognition and gait speed evaluation. Neuroimaging markers of cortical thickness, white matter hyperintensity, lacunae, and cerebral microbleeds were examined through brain magnetic resonance imaging.

RESULTS

The OCT-A parameters, including vessel density, were comparable between the patients with CADASIL and the controls. In patients with CADASIL, vessel density in the superficial retinal plexus in the macula as was inner retinal thickness was significantly lower in the stroke than the nonstroke subgroup. Macular vessel density and inner retinal thickness were positively correlated with gait speed, while negatively correlated with number of lacunae.

CONCLUSIONS

OCT-A is potentially a useful tool for evaluating disease severity, ischaemic burden, and neurodegeneration in patients with advanced CADASIL.

R558C NOTCH3 Mutation in a CADASIL Patient with Intracerebral Hemorrhage: A Case Report with Literature Review

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic cerebral small-vessel disease, which is characterized by migraine, recurrent ischemic strokes, psychiatric disorder, progressive cognitive decline, and occasionally intracerebral hemorrhage (ICH). ICH events have been reported in a high proportion of East Asian CADASIL patients with R544C mutation in exon 11 of NOTCH3; however, whether any other specific NOTCH3 mutation determines the ICH phenotype has yet to be explored.

CASE PRESENTATION

We report the case of a 60-year-old male CADASIL patient with a novel R558C mutation in exon 11 of the NOTCH3 gene, who presented with ICH in the basal ganglia and cerebellum. Brain imaging revealed multiple confluent white matter hyperintensities and abundant cerebral microbleeds (CMBs) in the bilateral basal ganglia, thalamus, and cerebellum. The patient had been having recurrent ischemic strokes prior to this ICH event, and had taken antiplatelet and antihypertensive agents for six months. We analyzed the possible reasons for ICH onset in the patient to recommend certain guidelines for the clinic.

CONCLUSIONS

Novel R558C mutation-related CADASIL vasculopathy and numerous CMBs, uncontrolled hypertension, and antiplatelet therapy could collectively contribute to ICH onset in the patient with CADASIL. These findings suggest that a diagnosis of CADASIL should also be considered when patients present with ICH, whenever MRI imaging reveals typical white matter abnormalities. Furthermore, this case report emphasizes the importance of CMB assessment, appropriate blood pressure control, and cautious assessment of the risk-benefits of antiplatelet medication in patients with 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.

Etiology and risk factors of intracranial hemorrhage and ischemic stroke in young adults

BACKGROUND

Young stroke incidence has increased worldwide with lifestyle changes. Etiology and risk factors for both ischemic and hemorrhagic stroke in young Asians remain underexplored.

METHODS

We retrospectively reviewed consecutive acute stroke patients aged 16-45 years admitted to the Taipei Veterans General Hospital between 2009 and 2019 to analyze etiologic subtypes, risk factors, and serial modified Rankin Scale scores for 1 year and compare the age groups of 16-30 and 31-45 years.

RESULTS

Among 670 young Taiwanese patients (mean age at onset 37.5 ± 7.0 years; male 65.1%), there were 366 nontraumatic spontaneous hemorrhagic stroke (including 259 intracerebral hemorrhage [ICH] and 107 subarachnoid hemorrhage, SAH), 292 ischemic stroke and 12 cerebral venous thromboses. Notably, ICH was more prevalent in patients aged 16-30 than in those aged 31-45 (54.8% vs 36.8%). Specifically, structural vasculopathy (e.g., arteriovenous malformation, cavernoma) was the most common etiologic subtype in patients aged 16-30 (p < 0.001), whereas hypertensive ICH was the most common subtype in patients aged 31-45 (p < 0.001). On the other hand, the top ischemic subtype for both age groups was other determined diseases (e.g., arterial dissection, autoimmune diseases, moyamoya disease, etc.) rather than large artery atherosclerosis. Hyperlipidemia, diabetes, and cigarette smoking were more common risk factors for infarction than ICH. Familial stroke patients whose first- or second-degree relatives had a stroke by age 80 (n = 104, 15.5%) had more infarctions than those without a familial stroke history. In multivariate analyses, initial stroke severity, and infarction type were important predictors of favorable outcomes after 3 months. At the 1-year follow-up, patients with ICH and SAH had worse functional outcomes and survival rates than those with infarction.

CONCLUSION

An aggressive approach to elucidate the etiology of stroke is indicated because structural vasculopathy-induced ICH and other determined infarction are distinctively prevalent in young adults, particularly those aged 16-30.

Prominent juxtacortical white matter lesion hallmarks NOTCH3-related intracerebral haemorrhage

Background and purpose

NOTCH3 p.R544C mutation accounts for 5% of spontaneous intracerebral haemorrhage (ICH) in East Asian patients. We investigated whether certain CT features are associated with NOTCH3-related ICH.

Methods

Patients with spontaneous ICH from a prospective stroke registry were screened for NOTCH3 p.R544C mutation. The neuroimaging features on the initial non-contrast CT scans selected to predict NOTCH3 p.R544C mutation, including burden of white matter lesion (WML), degree of brain atrophy, number of lacunes, prominent juxtacortical WML and prominent lobar lacunes, were analysed by neuroradiologists blinded to the mutation status.

Results

Of 299 patients with spontaneous ICH (mean age, 61 years; male, 68%; ICH volumes, 14.1±17.8 mL), 13 patients (4.3%) carried NOTCH3 p.R544C mutation. The clinical features, haematoma size and location were similar between NOTCH3 p.R544C mutation carriers and non-carriers. The CT scan revealed that patients with NOTCH3 p.R544C mutation had more severe WML and more frequently had prominent juxtacortical WML (69.2% vs 17.8%, p<0.001), and the effects were not driven by ageing as seen in patients without mutation. Prominent juxtacortical WML (area under receiver operating characteristic curve=0.76) outperformed the total WML score and prominent lobar lacunes and significantly predicted NOTCH3 p.R544C mutation in a multivariable-adjusted model (OR, 20.9; 95% CI 4.94 to 88.6).

Conclusion

In patients with spontaneous ICH, the severity and topographic distribution of WML can help in identifying potential NOTCH3 mutation-related ICH.

NOTCH3 variants are more common than expected in the general population and associated with stroke and vascular dementia: an analysis of 200 000 participants

BACKGROUND

Cysteine-altering NOTCH3 variants identical to those causing the rare monogenic form of stroke, CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), have been reported more common than expected in the general population, but their clinical significance and contribution to stroke and dementia risk in the community remain unclear.

METHODS

Cysteine-altering NOTCH3 variants were identified in UK Biobank whole-exome sequencing data (N=200 632). Frequency of stroke, vascular dementia and other clinical features of CADASIL, and MRI white matter hyperintensity volume were compared between variant carriers and non-carriers. MRIs from those with variants were visually rated, each matched with three controls.

RESULTS

Of 200 632 participants with exome sequencing data available, 443 (~1 in 450) carried 67 different cysteine-altering NOTCH3 variants. After adjustment for various covariates, NOTCH3 variant carriers had increased risk of stroke (OR: 2.33, p=0.0004) and vascular dementia (OR: 5.00, p=0.007), and increased white matter hyperintensity volume (standardised difference: 0.52, p<0.001) and white matter ultrastructural damage on diffusion MRI (standardised difference: 0.72, p<0.001). On visual analysis of MRIs from 47 carriers and 148 matched controls, variants were associated with presence of lacunes (OR: 5.97, p<0.001) and cerebral microbleeds (OR: 4.38, p<0.001). White matter hyperintensity prevalence was most increased in the anterior temporal lobes (OR: 7.65, p<0.001) and external capsule (OR: 13.32, p<0.001).

CONCLUSIONS

Cysteine-changing NOTCH3 variants are more common in the general population than expected from CADASIL prevalence and are risk factors for apparently 'sporadic' stroke and vascular dementia. They are associated with MRI changes of small vessel disease, in a distribution similar to that seen in CADASIL.

Mutations in NOTCH3 Gene may Promote the Clinical Presentation of Spinocerebellar Ataxia Type 37 Caused by Mutations in DAB1 Gene

Background: Autosomal dominant spinocerebellar ataxia type 37 (SCA37) and Cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy (CADASIL) result from DAB1 and NOTCH3 gene mutations, respectively.

Methods: In addition to conventional diagnostic methods, next-generation sequencing (NGS) and Sanger sequencing were performed to define and confirm the DAB1 and NOTCH3 gene mutation for a Chinese pedigree. Bioinformatics analysis was also applied for the mutated DAB1 and NOTCH3 protein using available software tools.

Results: Brain magnetic resonance imaging shows diffuse leukoencephalopathy and cerebellar atrophy in the proband. NGS and Sanger sequencing identified two novel heterozygous mutations: NM_021080:c.318T > G (p.H106Q) in the DAB1 gene and NM_000435:c.3298C > T (p.R1100C) in the NOTCH3 gene. Bioinformatics analysis suggested that the DAB1 and NOTCH3 gene mutations are disease-causing and may be responsible for the phenotypes.

Conclusion: This is the first report of a pedigree with both SAC37 and CADASIL phenotypes carrying corresponding gene mutations. Mutations in the NOTCH3 gene may promote the clinical presentation of spinocerebellar ataxia type 37 caused by mutations in the DAB1 gene. In addition to general examinations, it is vital for physicians to apply molecular genetics to get an accurate diagnosis in the clinic, especially for rare diseases.

Genotypic and Phenotypic Characteristics of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy from China

BACKGROUND AND PURPOSE

Studies have shown characteristics of genotypes and phenotypes in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This study aimed to describe the clinical and genetic characteristics of and correlations between the genotypes and phenotypes observed in CADASIL in China on the basis of exon classification.

METHODS

Consecutive Chinese patients with CADASIL were evaluated. The detailed clinical and genetic features of CADASIL patients were collected. Genotypic and phenotypic characteristics were compared among 3 CADASIL groups: group 1 included patients with NOTCH3 mutations in exons 3-4, group 2 included those with NOTCH3 mutations in exon 11, and group 3 included those with NOTCH3 mutations in other exons.

RESULTS

A total of 46 patients with CADASIL were evaluated. A comparison of 3 groups with mutations in different NOTCH3 exons revealed that individuals with exon 11 mutations were diagnosed at the oldest age, had the lowest modified Rankin Scale (mRS) scores, and were most likely to have basal ganglia (BG) enlarged perivascular spaces (EPVS) > 20 and atrophy. There were no significant clinical or neuroimaging differences between patients with mutations in exons 3-4 and those with mutations in other exons.

CONCLUSIONS

Clinical and neuroimaging features are different among Chinese patients with mutations in exons 3-4, exon 11, or other exons. Exon 11 showed characterized phenotype (the oldest age at diagnosis, the lowest mRS scores, and were most likely to have BG EPVS > 20 and atrophy), there were no significant differences between exons 3-4 and other exons.

Genetic profiles of 103,106 individuals in the Taiwan Biobank provide insights into the health and history of Han Chinese

Personalized medical care focuses on prediction of disease risk and response to medications. To build the risk models, access to both large-scale genomic resources and human genetic studies is required. The Taiwan Biobank (TWB) has generated high-coverage, whole-genome sequencing data from 1492 individuals and genome-wide SNP data from 103,106 individuals of Han Chinese ancestry using custom SNP arrays. Principal components analysis of the genotyping data showed that the full range of Han Chinese genetic variation was found in the cohort. The arrays also include thousands of known functional variants, allowing for simultaneous ascertainment of Mendelian disease-causing mutations and variants that affect drug metabolism. We found that 21.2% of the population are mutation carriers of autosomal recessive diseases, 3.1% have mutations in cancer-predisposing genes, and 87.3% carry variants that affect drug response. We highlight how TWB data provide insight into both population history and disease burden, while showing how widespread genetic testing can be used to improve clinical care.

Intracerebral hemorrhage in CADASIL

BACKGROUND

Intracerebral hemorrhage (ICH) has been reported in few cases of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), mostly in hypertensive patients. We aimed to assess the clinical and radiological characteristics of patients with CADASIL who presented with ICH.

METHODS

A retrospective analysis of all neuroimaging exams of CADASIL patients hospitalized in our academic neurology department for acute cerebrovascular events was performed to find ICH. A systematic review of the literature was performed on this topic.

RESULTS

Including our five patients, a total number of 52 subjects with CADASIL and ICH (mean age: 56 years, SD 11, 36-69%- male) were reported. Intracerebral hemorrhages were mainly deep (34 subjects), followed by lobar (8 subjects), infratentorial (6 subjects) and mixed locations (4 subjects). Three ICHs were asymptomatic. Fourteen patients were taking antithrombotic medication, 18 had no regular antiplatelet or anticoagulant treatment while in 20 patients medical treatment was not detailed. Arterial hypertension was present in 37 out of 51 patients with available information. Neuroimaging showed extensive FLAIR hyperintensities in all CADASIL subjects with ICH, cerebral microbleeds in all but three patients, and lacunar infarction in 19 out of 25 subjects with available information.

CONCLUSIONS

Intracerebral hemorrhage represents a possible yet uncommon manifestation of CADASIL and should be considered as a possibility in patients with ICH associated with leukoencephalopathy and microbleeds, even in the absence of other clinical symptoms.

Imaging-based pregenetic screening for NOTCH3 p.R544C mutation in ischemic stroke in Taiwan

Objective

To develop an easily applicable screening score to guide NOTCH3 p.R544C genetic testing for patients who presented with acute ischemic cerebrovascular events in Taiwan.

Methods

1734 patients who presented with ischemic cerebrovascular events were enrolled from the Formosa Stroke Genetic Consortium stroke registry and were screened for the NOTCH3 p.R544C mutation. Clinical and MRI characteristics of NOTCH3 p.R544C mutation carriers (n = 36) and a subset of noncarriers (n = 673) were tested in a logistic regression model to identify key features associated with the NOTCH3 p.R544C carrier status. Variables and their odds ratios in the regression model were used to develop the R544C screening score to predict positive NOTCH3 p.R544C test results.

Results

We constructed the R544C screening score using five clinical and imaging characteristics, including stroke onset before 50 years of age, the small vessel occlusion subtype, a family history of stroke/TIA in siblings, external capsule involvement, and advanced deep white matter hyperintensity. The area under the ROC curve of the screening score was 0.867 (95% CI = 0.810‐0.924). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 0.75, 0.88, 0.13, 0.99, and 0.88, respectively, for a cutoff score of 5 points. In addition, the R544C screening score was validated in another cohort composed of 235 stroke patients with comparable performance (area under the ROC curve = 0.957, 95% CI = 0.916‐0.997).

Interpretations

For Taiwanese patients presenting with acute ischemic cerebrovascular events, the R544C screening score is easily applicable and can efficiently select high‐risk patients for NOTCH3 p.R544C mutation test.

Plasma neurofilament light chain and glial fibrillary acidic protein predict stroke in CADASIL

Background

Stroke remains the most cumbersome disease burden in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This study aimed to investigate whether plasma biomarkers can reflect disease severity and predict stroke recurrence in CADASIL patients.

Methods

Sixty-three CADASIL patients (mean age 58.9 ± 9.3 years old, male 63%) from a multicenter registry and 17 controls were recruited. Plasma biomarkers, namely neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), tau, and ubiquitin carboxy-terminal hydrolase L1 (UCHL1), were measured using an ultra-sensitive single molecule array at baseline. Neuroimaging markers assessed included the Fazekas scale of white matter hyperintensity, numbers of lacunes, and cerebral microbleeds (CMBs). Cox proportional hazards regression models were applied to calculate the hazard ratio (HR) of plasma biomarkers at baseline for predicting incident stroke during follow-up.

Results

Plasma NfL, GFAP, and UCHL1 levels were significantly elevated in the CADASIL patients than in the controls. Among the CADASIL patients, both plasma NfL and GFAP levels positively correlated with the numbers of CMBs (r = 0.32 and r = 0.37, respectively; both p < 0.05). Higher plasma levels of NfL and GFAP were associated with any stroke (odds ratio 2.02, 95% confidence interval [CI] 1.06–3.87) and ICH (odds ratio 2.06, 95% CI 1.26–3.35) at baseline, respectively. Within a mean follow-up period of 3.1 ± 2.1 years, 10 patients (16%) had incident stroke and 6 of them were ICH. Higher baseline NfL (HR 1.93, 95% CI 1.19–3.13) predicted any incident stroke, whereas higher GFAP (HR 2.80, 95% CI 1.21–6.53) predicted incident ICH.

Conclusions

In CADASIL patients, plasma NfL can be a promising biomarker for monitoring incident stroke, whereas GFAP may have a role in cerebral hemorrhage.

NOTCH3 cysteine-altering variant is an important risk factor for stroke in the Taiwanese population

OBJECTIVE

To test the hypothesis that the prevalence and clinical effect of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) have been underestimated in Asian populations.

METHODS

The Taiwan Biobank, containing 1,517 Taiwanese genome sequences, was queried for pathogenic NOTCH3 cysteine-altering mutations. NOTCH3 mutations identified in the reference population were genotyped in 7,038 stroke- and dementia-free individuals and 800 patients with ischemic stroke. NOTCH3 genotyping, clinical manifestations, and the severity of white matter lesions on MRI were compared between the 2 groups.

RESULTS

Three cysteine-altering NOTCH3 variants (p.R544C, p.C853Y, and p.C884Y) were identified from the Taiwan Biobank. We confirmed that the NOTCH3 p.R544C mutation was present in a significant number of individuals in Taiwan, including 60 of the 7,038 healthy controls (0.9%), 17 of the 800 patients with ischemic stroke (2.1%), and 16 of the 245 patients with small vessel occlusion (SVO) stroke (6.5%). The other 2 cysteine-altering mutations were rarely detected. After adjusting for vascular risk factors, harboring the p.R544C variant resulted in a 3.40-fold increased risk for overall stroke and an 11.05-fold increased risk for SVO stroke (p = 0.0001 and 3.9 × 10^-10, respectively). Three symptom-free individuals carrying the p.R544C mutation had extensive leukoencephalopathy typical of CADASIL at age 59, 66, and 67, suggesting that p.R544C-related CADASIL could remain subclinical at advanced age.

CONCLUSION

The NOTCH3 p.R544C variant is an important risk factor for SVO stroke in Taiwan. Phenotypic variation among individuals carrying a NOTCH3 mutation indicates the existence of disease-modifying factors in CADASIL.

Novel Characteristics of Race-Specific Genetic Functions in Korean CADASIL

Background and Objectives: Previous studies found differences in the characteristics of NOTCH3 mutations in Caucasians and Asians with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Therefore, we sought to investigate the correlations between genetic and clinical/radiological findings in Korean CADASIL patients including some variants of unknown significance (VUS). Materials and Methods: We screened 198 patients with a suspected diagnosis of CADASIL between 2005 and 2015 via Sanger sequencing. Results: A total of 34 subjects (52.5 ± 9.5 years) were included. The majority of the mutations were in exon 3 and exon 11. R75P mutations (n = 5), followed by Y465C and R544C mutations (n = 4) were the most prevalent. Patients with those mutations exhibited less frequent anterior temporal (AT) or external capsular (EC) hyperintensities compared to patients with other locus mutations. Hemorrhagic stroke (HS) was found to be associated with mutations in exon 3 (R75P), exon 9 (Y465C), exon 11 (R587C), and exon 22 (R1175W variants), which were common locations in our study. Although it is unclear that genetic differences might affect the phenotypes in ethnicities, Asian population shows less migraine or seizure, but more intracerebral hemorrhage. Unlike in westernized countries, typical AT or EC hyperintensities may not be significant MRI markers, at least in Korean CADASIL patients. Furthermore, similar to R75P phenotypes, it is a novel finding that patients with Y465C and R1175W VUS have less frequent AT involvement than Caucasians. Conclusion: The associations between HS and common genetic locations account for the increased development of intracerebral hemorrhage in Koreans rather than Caucasians. We suggest that some CADASIL mutations appear to impart novel region-specific characteristics.