Mutational and haplotype map of NOTCH3 in a cohort of Italian patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Headache and NOTCH3 Gene Variants in Patients with CADASIL

Autosomal dominant cerebral arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited vascular disease characterized by recurrent strokes, cognitive impairment, psychiatric symptoms, apathy, and migraine. Approximately 40% of patients with CADASIL experience migraine with aura (MA). In addition to MA, CADASIL patients are described in the literature as having migraine without aura (MO) and other types of headaches. Mutations in the NOTCH3 gene cause CADASIL. This study investigated NOTCH3 genetic variants in CADASIL patients and their potential association with headache types. Genetic tests were performed on 30 patients with CADASIL (20 women aged 43.6 ± 11.5 and 10 men aged 39.6 ± 15.8). PCR-HRM and sequencing methods were used in the genetic study. We described three variants as pathogenic/likely pathogenic (p.Tyr189Cys, p.Arg153Cys, p.Cys144Arg) and two benign variants (p.Ala202=, p.Thr101=) in the NOTCH3 gene and also presented the NOTCH3 gene variant (chr19:15192258 G>T), which has not been previously described in the literature. Patients with pathogenic/likely pathogenic variants had similar headache courses. People with benign variants showed a more diverse clinical picture. It seems that different NOTCH3 variants may contribute to the differential presentation of a CADASIL headache, highlighting the diagnostic and prognostic value of headache characteristics in this disease.

NOTCH3 C201R variant causes cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) that can be confused with early-onset Alzheimer's disease

BACKGROUND

NOTCH3 is the causative gene for autosomal dominant cerebral arteriopathy with subcortical infarctions and leukoencephalopathy (CADASIL) which is associated with both stroke and dementia. When CADASIL presents primarily as dementia it can be difficult to distinguish from Alzheimer's disease (AD) at both the clinical and neuropathological levels.

METHODS

We performed exome sequencing of several affected individuals from a large family affected with AD. PCR amplification and direct Sanger sequencing were used to verify variants detected by exome analysis and to screen family members at-risk to carry those variants. Neuropathologic brain evaluation by immunohistochemistry and MRI were performed for the carriers of the NOTCH3 variant.

RESULTS

In a three-generation family with AD, we found a c.601 T > C p.Cys201Arg variant in the NOTCH3 gene that caused clinical and neuropathological manifestations of CADASIL. These features included earlier onset of dementia accompanied by behavioral abnormalities in the father and son and white matter abnormalities in the asymptomatic grandson. The family is one branch of a large pedigree studied by the Alzheimer's Disease Sequencing Project (ADSP). As part of the ADSP linkage analysis and whole genome sequencing endeavor, an ABCA1 variant, p.Ala937Val, was previously found associated with AD in this pedigree.

CONCLUSIONS

Our findings, together with other reported pathogenic missense variants of the C201 codon in NOTCH3, support the role of cysteine 201 as a mutation hotspot for CADASIL and highlight the genetic complexity both clinically and pathologically of AD and related dementia.

Genetic Study of Cerebral Small Vessel Disease in Chinese Han Population

Cerebral small vessel disease (CSVD) is a syndrome of clinical, neuroimaging, and neuropathological manifestations caused by disorders that affect small cerebral vessels. Although the pathogenesis of the disease remains unclear, some studies have demonstrated that genetic variants contribute to the development of CSVD. Our study aimed to explore the genetic characteristics of CSVD in the Chinese Han population. We enrolled 182 sporadic CSVD Chinese Han patients whose magnetic resonance imaging results showed grade 2-3 white matter lesions. Target region sequencing of seven monogenic CSVD-related genes, including NOTCH3, HTRA1, COL4A1, COL4A2, GLA, TREX1, and CTSA, was performed, and we identified pathogenic variants by screening the sequencing results and functional predictive analysis. All variants were predicted to be pathogenic by the SIFT Score, Polymorphism Phenotyping-2 score, Mutation Taster, Splice site score calculation, and MaxEntScan. All variants were validated in 300 healthy controls. In total, eight variants were identified in patients with CSVD, including five novel variants, c.1774C>T (NOTCH3), c.3784C>T (NOTCH3), c. 1207C>T (HTRA1), and c. 1274+1G> A (HTRA1), c.1937G>C (COL4A1) and three reported mutations. None of these variants were present in 300 healthy controls. No pathogenic variants in COL4A2, GLA, TREX1, and CTSA were detected. This study identified five novel variants in CSVD-related genes in Chinese Han patients with sporadic CSVD. Our results expand the genetic profile of CSVD.

Identification of recurrent genetic patterns from targeted sequencing panels with advanced data science: a case-study on sporadic and genetic neurodegenerative diseases

Background

Targeted Next Generation Sequencing is a common and powerful approach used in both clinical and research settings. However, at present, a large fraction of the acquired genetic information is not used since pathogenicity cannot be assessed for most variants. Further complicating this scenario is the increasingly frequent description of a poli/oligogenic pattern of inheritance showing the contribution of multiple variants in increasing disease risk. We present an approach in which the entire genetic information provided by target sequencing is transformed into binary data on which we performed statistical, machine learning, and network analyses to extract all valuable information from the entire genetic profile. To test this approach and unbiasedly explore the presence of recurrent genetic patterns, we studied a cohort of 112 patients affected either by genetic Creutzfeldt–Jakob (CJD) disease caused by two mutations in the PRNP gene (p.E200K and p.V210I) with different penetrance or by sporadic Alzheimer disease (sAD).

Results

Unsupervised methods can identify functionally relevant sources of variation in the data, like haplogroups and polymorphisms that do not follow Hardy–Weinberg equilibrium, such as the NOTCH3 rs11670823 (c.3837 + 21 T > A). Supervised classifiers can recognize clinical phenotypes with high accuracy based on the mutational profile of patients. In addition, we found a similar alteration of allele frequencies compared the European population in sporadic patients and in V210I-CJD, a poorly penetrant PRNP mutation, and sAD, suggesting shared oligogenic patterns in different types of dementia. Pathway enrichment and protein–protein interaction network revealed different altered pathways between the two PRNP mutations.

Conclusions

We propose this workflow as a possible approach to gain deeper insights into the genetic information derived from target sequencing, to identify recurrent genetic patterns and improve the understanding of complex diseases. This work could also represent a possible starting point of a predictive tool for personalized medicine and advanced diagnostic applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01173-4.

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.

Notch3 Signaling and Aggregation as Targets for the Treatment of CADASIL and Other NOTCH3-Associated Small-Vessel Diseases

Mutations in the NOTCH3 gene can lead to small-vessel disease in humans, including the well-characterized cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a condition caused by NOTCH3 mutations altering the number of cysteine residues in the extracellular domain of Notch3. Growing evidence indicates that other types of mutations in NOTCH3, including cysteine-sparing missense mutations or frameshift and premature stop codons, can lead to small-vessel disease phenotypes of variable severity or penetrance. There are currently no disease-modifying therapies for small-vessel disease, including those associated with NOTCH3 mutations. A deeper understanding of underlying molecular mechanisms and clearly defined targets are needed to promote the development of therapies. This review discusses two key pathophysiological mechanisms believed to contribute to the emergence and progression of small-vessel disease associated with NOTCH3 mutations: abnormal Notch3 aggregation and aberrant Notch3 signaling. This review offers a summary of the literature supporting and challenging the relevance of these mechanisms, together with an overview of available preclinical experiments derived from these mechanisms. It highlights knowledge gaps and future research directions. In view of recent evidence demonstrating the relatively high frequency of NOTCH3 mutations in the population, and their potential role in promoting small-vessel disease, progress in the development of therapies for NOTCH3-associated small-vessel disease is urgently needed.

George-Hyslop P, Londos E, Zetterberg H, Morgan K, Troakes C, Al-Sarraj S, Lashley T, Holton J, Compta Y, Van Deerlin V, Trojanowski JQ, Serrano GE, Beach TG, Lesage S, Galasko D, Masliah E, Santana I, Pastor P, Tienari PJ, Myllykangas L, Oinas M, Revesz T, Lees A, Boeve BF, Petersen RC, Ferman TJ, Escott-Price V, Graff-Radford N, Cairns NJ, Morris JC, Pickering-Brown S, Mann D, Halliday G, Stone DJ, Dickson DW, Hardy J, Singleton A, Guerreiro R, Bras J. Analysis of neurodegenerative disease-causing genes in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a clinically heterogeneous disorder with a substantial burden on healthcare. Despite this, the genetic basis of the disorder is not well defined and its boundaries with other neurodegenerative diseases are unclear. Here, we performed whole exome sequencing of a cohort of 1118 Caucasian DLB patients, and focused on genes causative of monogenic neurodegenerative diseases. We analyzed variants in 60 genes implicated in DLB, Alzheimer’s disease, Parkinson’s disease, frontotemporal dementia, and atypical parkinsonian or dementia disorders, in order to determine their frequency in DLB. We focused on variants that have previously been reported as pathogenic, and also describe variants reported as pathogenic which remain of unknown clinical significance, as well as variants associated with strong risk. Rare missense variants of unknown significance were found in APP, CHCHD2, DCTN1, GRN, MAPT, NOTCH3, SQSTM1, TBK1 and TIA1. Additionally, we identified a pathogenic GRN p.Arg493* mutation, potentially adding to the diversity of phenotypes associated with this mutation. The rarity of previously reported pathogenic mutations in this cohort suggests that the genetic overlap of other neurodegenerative diseases with DLB is not substantial. Since it is now clear that genetics plays a role in DLB, these data suggest that other genetic loci play a role in this disease.

Recognition of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) in Two Oligosymptomatic Sisters with Low CADASIL Scale Scores and a Venous Dysplasia: Report of a Novel Greek Family

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) due to mutations of the NOTCH3 gene is the most common cause of inherited cerebral small-vessel disease and one of the genetic causes of migraine with aura. The so-called CADASIL scale has been proposed as a clinical screening tool, and a score of 15 or higher seems useful in identifying patients with high probability of carrying NOTCH3 mutations. We studied a novel Greek family with clinical features compatible with CADASIL. Genetic analysis of NOTCH3 in the 2 living patients revealed the R182C mutation. Both patients had low scores (12 and 14) in the CADASIL scale, probably due to their relatively young age (38 and 37 years, respectively) at which cognitive decline and external capsule involvement have not developed yet. Another unusual feature in the second patient was a venous dysplasia in the parietal lobe. Observations presented here add to the notion that the CADASIL scale, although useful, probably needs a revision, taking into account the patient's age at which the score is calculated.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoancepahlopathy presenting with postpartum psychosis and late-onset stroke

Aim: To describe the unusual presentation of a novel family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoancepahlopathy. Presentation of cases: The clinical features of five patients from three successive generations are described. The index patient presented with postpartum psychosis followed by cognitive decline. Brain imaging revealed no temporal pole involvement. Genetic testing was performed by full scan of the entire NOTCH3 gene revealing the R169C mutation. Multiple cardiovascular risk factors and late-onset strokes were present in the family. Conclusion: The combination of atypical psychiatric onset, absence of anterior temporal lesions, presence of cardiovascular risk factors and late-onset stroke may obscure the correct diagnosis for many years and requires a high index of suspicion.

APOE and AGT in the Finnish p.Arg133Cys CADASIL population

BACKGROUND

CADASIL is an inherited systemic small vessel disease, the affected status of brain vessels leading to subcortical vascular dementia. The defective gene is NOTCH3 in which over 230 different pathogenic mutations have been identified. The clinical course of CADASIL is highly variable even within families. Previous studies have shown that additional genetic factors modify the phenotype.

AIMS AND METHODS

Altogether, 134 Finnish CADASIL patients with p.Arg133Cys mutation were analysed for possible associations between the apolipoprotein E (APOE) genotype, angiotensinogen (AGT) p.Met268Thr polymorphism or neutral p.Ala202Ala NOTCH3 polymorphism and earlier first-ever stroke or migraine.

RESULTS

We found no association between the APOE genotypes, AGT polymorphism, NOTCH3 polymorphism and earlier first-ever stroke or migraine.

CONCLUSIONS

The APOE, AGT and NOTCH3 polymorphism did not modify the onset of strokes or migraine in our CADASIL sample, which is one of the largest mutationally homogenous CADASIL populations published to date. International collaboration, pooled analyses and genomewide approaches are warranted to identify the genetic factors that modify the highly variable CADASIL phenotype.

Characterization of CADASIL among the Han Chinese in Taiwan: Distinct Genotypic and Phenotypic Profiles

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is originally featured with a strong clustering of mutations in NOTCH3 exons 3–6 and leukoencephalopathy with frequent anterior temporal pole involvement. The present study aims at characterizing the genotypic and phenotypic profiles of CADASIL in Taiwan. One hundred and twelve patients with CADASIL from 95 families of Chinese descents in Taiwan were identified by Sanger sequencing of exons 2 to 24 of NOTCH3. Twenty different mutations in NOTCH3 were uncovered, including 3 novel ones, and R544C in exon 11 was the most common mutation, accounting for 70.5% of the pedigrees. Haplotype analyses were conducted in 14 families harboring NOTCH3 R544C mutation and demonstrated a common haplotype linked to NOTCH3 R544C at loci D19S929 and D19S411. Comparing with CADASIL in most Caucasian populations, CADASIL in Taiwan has several distinct features, including less frequent anterior temporal involvement, older age at symptom onset, higher incidence of intracerebral hemorrhage, and rarer occurrence of migraine. Subgroup analyses revealed that the R544C mutation is associated with lower frequency of anterior temporal involvement, later age at onset and higher frequency of cognitive dysfunction. In conclusion, the present study broadens the spectrum of NOTCH3 mutations and provides additional insights for the clinical and molecular characteristics of CADASIL patients of Han-Chinese descents.

CADASIL in central Italy: a retrospective clinical and genetic study in 229 patients

The objective of the study is to detail clinical and NOTCH3 gene mutational spectrum in a large group of Italian CADASIL patients. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a familial cerebral small vessels disease caused by mutations in the NOTCH3 gene on 19p13 usually presenting in young or middle adulthood. Characteristic features include migraine, recurrent lacunar stroke, subcortical dementia, mood disturbances and leukoencephalopathy. The disorder is often overlooked and misdiagnosed. CADASIL prevalence and disease burden is still undetermined. We retrospectively reviewed demographic, clinical, and mutational characteristic of all CADASIL patients diagnosed from January 2002 to December 2012 in three referral centers for neurogenetic and cerebrovascular diseases in central Italy. 229 NOTCH3 positive subjects were identified. Mean age at diagnosis was 57.8 ± 14.7 years, and 48.6 ± 17.1 years at first symptom onset. Most frequent clinical symptoms were ischemic events (59 %) and psychiatric disturbances (48 %). The highest percentage of mutations were found on exons 4 and 19 (20.6 and 17.6 % respectively), the remaining being dispersed over the entire EGF-like region of the NOTCH3 gene. 209 patients resided in a circumscribed geographic area which included three regions of the central Italy, yielding a minimum prevalence of 4.1 per 100.000 adult inhabitants. This is the most extensive study on CADASIL in Italy. Clinical phenotype showed several peculiarities in frequency and presentation of the main disease manifestations. Our study enlarges the number of pathogenic NOTCH3 mutations and due to the heterogeneous mutational spectrum observed suggests that full sequencing of exons 2-24 is mandatory for CADASIL screening in the Italian population.

Hypomorphic NOTCH3 mutation in an Italian family with CADASIL features

The cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is because of NOTCH3 mutations affecting the number of cysteine residues. In this view, the role of atypical NOTCH3 mutations is still debated. Therefore, we investigated a family carrying a NOTCH3 nonsense mutation, with dominantly inherited recurrent cerebrovascular disorders. Among 7 family members, 4 received a clinical diagnosis of CADASIL. A heterozygous truncating mutation in exon 3 (c.307C>T, p.Arg103X) was found in the 4 clinically affected subjects and in one 27-year old lady, only complaining of migraine with aura. Magnetic resonance imaging scans found typical signs of small-vessel disease in the 4 affected subjects, supporting the clinical diagnosis. Skin biopsies did not show the typical granular osmiophilic material, but only nonspecific signs of vascular damage, resembling those previously described in Notch3 knockout mice. Interestingly, messenger RNA (mRNA) analysis supports the hypothesis of an atypical NOTCH3 mutation, suggesting a nonsense-mediated mRNA decay. In conclusion, the present study broadens the spectrum of CADASIL mutations, and, therefore, opens new insights about Notch3 signaling.

Mutational screening of NOTCH3 gene reveals two novel mutations: complexity of CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult onset hereditary vascular disease with neurological manifestations. The classical clinical course is relentlessly progressive with early transient ischaemic attacks (TIA) or strokes, dementia and finally death in the mid-1960s. The disorder is inherited in an autosomal dominant fashion, with high penetrance and broad variable clinical course even within family. It is caused by mutations in the NOTCH3 gene; all causative mutations result in gain or loss of a cysteine residue within the extracellular domain, with exons 3 and 4 reported as hot spot mutational sites. Mutation analysis of the NOTCH3 gene was performed through direct sequencing of the 2-23 exons containing all EGF-like domains. Patients underwent genetic counselling pre and post testing. Here, we report two novel mutations located in exons 6 and 15 of the NOTCH3 gene; clinical description for the probands and for available relatives is enclosed. No reliable data on incidence or prevalence rates of this disease are available: it is therefore essential that the diagnosis is obtained in all suspected cases through the extensive analysis of the NOTCH3 gene and that all cases are brought to the attention of the scientific community.

Spectrum of NOTCH3 mutations in Korean patients with clinically suspicious cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by mutations in the NOTCH3 gene on chromosome 19. Previous studies showed that NOTCH3 contains mutational hotspots that can vary among individuals of different ethnic backgrounds. In this study, we investigated the spectrum of NOTCH3 mutations in Korean patients with CADASIL. We retrospectively analyzed 156 patients who underwent NOTCH3 gene testing for molecular diagnosis of CADASIL using Sanger sequencing with a tiered approach. First, we screened previously reported mutational hotspots (exons 2-6, 8, 11, 18, 19, and 22). If no mutation was detected and samples were available, we extended our analysis to additional exons (7, 9, 10, 14, 15, 20, 21, 23, and 25). In 45 of 156 patients (28.8%), 29 mutations and 16 novel variants of unknown significance (VUS) were identified. The p.R544C mutation in exon 11 of NOTCH3 was the most frequently observed mutation (n = 8), followed by p.R75P in exon 3 (n = 7), p.R332C in exon 6 (n = 3), p.R54C in exon 2 (n = 2), and p.R90C in exon 3 (n = 2). Among the VUS, p.R1175W in exon 22, p.S414C in exon 8, and p.N1207S in exon 22 were found in 5, 3, and 2 patients, respectively. Other mutations and VUS were observed in 1 patient each. Although this was not a prospective, nationwide cohort study, the results above suggested that the spectrum of NOTCH3 mutations might be different in Koreans than in individuals of Caucasian ethnicity. Therefore, further analysis of Koreans with CADASIL might be necessary to implement a Korean-specific mutation screening paradigm.

Role of electron microscopy in the diagnosis of cadasil syndrome: a study of 32 patients

Background and Purpose

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by NOTCH3 gene mutations that result in vascular smooth muscle cell (VSMC) degeneration. Its distinctive feature by electron microscopy (EM) is granular osmiophilic material (GOM) detected in VSMC indentations and/or the extracellular space close to VSMCs. Reports of the sensitivity of EM in detecting GOM in biopsies from CADASIL patients are contradictory. We present data from 32 patients clinically suspected to have CADASIL and discuss the role of EM in its diagnosis in this retrospective study.

Methods

Skin, skeletal muscle, kidney and pericardial biopsies were examined by EM; the NOTCH3 gene was screened for mutations. Skin and muscle biopsies from 12 patients without neurological symptoms served as controls.

Results and Discussion

All GOM-positive patients exhibited NOTCH3 mutations and vice versa. This study i) confirms that EM is highly specific and sensitive for CADASIL diagnosis; ii) extends our knowledge of GOM distribution in tissues where it has never been described, e.g. pericardium; iii) documents a novel NOTCH3 mutation in exon 3; and iv) shows that EM analysis is critical to highlight the need for comprehensive NOTCH3 analysis. Our findings also confirm the genetic heterogeneity of CADASIL in a small Italian subpopulation and emphasize the difficulties in designing algorithms for molecular diagnosis.

Brain pericyte plasticity as a potential drug target in CNS repair

Brain pericytes (BrPCs) are essential cellular components of the central nervous system neurovascular unit involved in the regulation of blood flow, blood-brain barrier function, as well as in the stabilization of the vessel architecture. More recently, it became evident that BrPCs, besides their regulatory activities in brain vessel function and homeostasis, have pleiotropic functions in the adult CNS ranging from stromal and regeneration promoting activities to stem cell properties. This special characteristic confers BrPC cell plasticity, being able to display features of other cells within the organism. BrPCs might also be causally involved in certain brain diseases. Due to these properties BrPCs might be potential drug targets for future therapies of neurological disorders. This review summarizes BrPC properties, disorders in which this cell type might be involved, and provides suggestions for future therapeutic developments targeting BrPCs.