The spectrum of Notch3 mutations in 28 Italian CADASIL families

Microbleed clustering in thalamus sign in CADASIL patients with NOTCH3 R75P mutation

Background and objective

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebral microvascular disease characterized by the development of vascular dementia and lacunar infarctions. This study aimed to identify the genetic and clinical features of CADASIL in Japan.

Methods

We conducted genetic analysis on a case series of patients clinically diagnosed with CADASIL. Clinical and imaging analyses were performed on 32 patients with pathogenic mutations in the NOTCH3 gene. To assess the presence of cerebral microbleeds (CMBs), we utilized several established rating scales including the Fazekas scale, Scheltens rating scale, and Microbleed Anatomical Rating Scale, based on brain MRI images.

Results

Among the 32 CADASIL patients, 24 cases were found carrying the R75P mutation in NOTCH3, whereas the remaining eight cases had other NOTCH3 mutations (R75Q, R110C, C134F, C144F, R169C, and R607C). The haplotype analysis of the R75P mutation uncovered the presence of a founder effect. A brain MRI analysis revealed that cases with the R75P mutation had a significantly higher total number of CMBs, particularly in the thalamus when compared to patients with other NOTCH3 mutations. Among 15 out of 24 cases with the R75P mutation, we observed a notable clustering of CMBs in the thalamus, termed microbleed clustering in thalamus sign (MCT sign).

Conclusion

We propose that the MCT sign observed in NOTCH3 R75P-related CADASIL patients may serve as a potentially characteristic imaging feature. This finding offers further insights into the interactions between genotypes and phenotypes between NOTCH3 and CADASIL.

Non-convulsive status epilepticus as the initial manifestation in a family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant small-vessel disease caused by mutations of the NOTCH3 gene. It typically presents with migraine, recurrent brain ischaemia, and cognitive disorders. Seizures rarely present as the initial manifestation, with non-convulsive status epilepticus being even less frequent. We present a series of 3 related patients with this arteriopathy, 2 of whom presented status epilepticus as a manifestation of the disease.

CADASIL in Greece: Mutational spectrum and clinical characteristics based on a systematic review and pooled analysis of published cases

BACKGROUND

Differences have been noted in the clinical presentation and mutational spectrum of CADASIL among various geographical areas. The aim of the present study was to investigate the mode of clinical presentation and genetic mutations reported in Greece.

METHODS

After a systematic literature search, we performed a pooled analysis of all published CADASIL cases from Greece.

RESULTS

We identified 14 studies that reported data from 14 families comprising 54 patients. Migraine with aura was reported in 39%, ischemic cerebrovascular diseases in 68%, behavioral-psychiatric symptoms in 47% and cognitive decline in 60% of the patients. The mean (±SD) age of onset for migraine with aura, ischemic cerebrovascular diseases, behavioral-psychiatric symptoms and cognitive decline was 26.2 ± 8.7, 49.3 ± 14.6, 47.9 ± 9.4 and 42.9 ± 10.3, respectively; the mean age at disease onset and death was 34.6 ± 12.1 and 60.2 ± 11.2 years. With respect to reported mutations, mutations in exon 4 were the most frequently reported (61.5% of all families), with the R169C mutation being the most common (30.8% of all families and 50% of exon 4 mutations), followed by R182C mutation (15.4% of all families and 25% of exon 4 mutations).

CONCLUSIONS

The clinical presentation of CADASIL in Greece is in accordance with the phenotype encountered in Caucasian populations, but differs from the Asian phenotype, which is characterized by a lower prevalence of migraine and psychiatric symptoms. The genotype of Greek CADASIL pedigrees is similar to that of British pedigrees, exhibiting a high prevalence of exon 4 mutations, but differs from Italian and Asian populations, where mutations in exon 11 are frequently encountered.

Non-convulsive status epilepticus as the initial manifestation in a family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant small-vessel disease caused by mutations of the NOTCH3 gene. It typically presents with migraine, recurrent brain ischaemia, and cognitive disorders. Seizures rarely present as the initial manifestation, with non-convulsive status epilepticus being even less frequent. We present a series of 3 related patients with this arteriopathy, 2 of whom presented status epilepticus as a manifestation of the disease.

Notch3 in Development, Health and Disease

Notch3 is one of four mammalian Notch proteins, which act as signalling receptors to control cell fate in many developmental and adult tissue contexts. Notch signalling continues to be important in the adult organism for tissue maintenance and renewal and mis-regulation of Notch is involved in many diseases. Genetic studies have shown that Notch3 gene knockouts are viable and have limited developmental defects, focussed mostly on defects in the arterial smooth muscle cell lineage. Additional studies have revealed overlapping roles for Notch3 with other Notch proteins, which widen the range of developmental functions. In the adult, Notch3, in collaboration with other Notch proteins, is involved in stem cell regulation in different tissues in stem cell regulation in different tissues, and it also controls the plasticity of the vascular smooth muscle phenotype involved in arterial vessel remodelling. Overexpression, gene amplification and mis-activation of Notch3 are associated with different cancers, in particular triple negative breast cancer and ovarian cancer. Mutations of Notch3 are associated with a dominantly inherited disease CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and there is further evidence linking Notch3 misregulation to hypertensive disease. Here we discuss the distinctive roles of Notch3 in development, health and disease, different views as to the underlying mechanisms of its activation and misregulation in different contexts and potential for therapeutic intervention.

Investigating diagnostic sequencing techniques for CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. Our laboratory has been undertaking genetic diagnostic testing for CADASIL since 1997. Work originally utilised Sanger sequencing methods targeting specific NOTCH3 exons. More recently, next-generation sequencing (NGS)-based technologies such as a targeted gene panel and whole exome sequencing (WES) have been used for improved genetic diagnostic testing. In this study, data from 680 patient samples was analysed for 764 tests utilising 3 different sequencing technologies. Sanger sequencing was performed for 407 tests, a targeted NGS gene panel which includes NOTCH3 exonic regions accounted for 354 tests, and WES with targeted analysis was performed for 3 tests. In total, 14.7% of patient samples (n = 100/680) were determined to have a mutation. Testing efficacy varied by method, with 10.8% (n = 44/407) of tests using Sanger sequencing able to identify mutations, with 15.8% (n = 56/354) of tests performed using the NGS custom panel successfully identifying mutations and a likely non-NOTCH3 pathogenic variant (n = 1/3) identified through WES. Further analysis was then performed through stratification of the number of mutations detected at our facility based on the number of exons, level of pathogenicity and the classification of mutations as known or novel. A systematic review of NOTCH3 mutation testing data from 1997 to 2017 determined the diagnostic rate of pathogenic findings and found the NGS-customised panel increases our ability to identify disease-causing mutations in NOTCH3.

Notch Pathway and Inherited Diseases: Challenge and Promise

The evolutionary highly conserved Notch pathway governs many cellular core processes including cell fate decisions. Although it is characterized by a simple molecular design, Notch signaling, which first developed in metazoans, represents one of the most important pathways that govern embryonic development. Consequently, a broad variety of independent inherited diseases linked to defective Notch signaling has now been identified, including Alagille, Adams-Oliver, and Hajdu-Cheney syndromes, CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), early-onset arteriopathy with cavitating leukodystrophy, lateral meningocele syndrome, and infantile myofibromatosis. In this review, we give a brief overview on molecular pathology and clinical findings in congenital diseases linked to the Notch pathway. Moreover, we discuss future developments in basic science and clinical practice that may emerge from recent progress in our understanding of the role of Notch in health and disease.

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.

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.

CADASIL

Cerebral small-vessel disease is a prevalent condition that is strongly associated with ischemic stroke and dementia. The most prevalent inherited cause of cerebral small-vessel disease is CADASIL, cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy, a disorder linked to mutations in NOTCH3. The most common symptoms of CADASIL are small ischemic strokes and/or transient ischemic attacks and cognitive impairment, appearing in middle age, that may progress to frank vascular dementia. However, it is increasingly recognized that individual symptom types, onset, and disease severity span a wide spectrum, even among individuals in the same family. Magnetic resonance imaging in CADASIL reveals severe white-matter hyperintensities, evidence of prior subcortical strokes, and, in some cases, microhemorrhages. Several hundred mutations in NOTCH3 have been described worldwide in CADASIL, and virtually all of these mutations alter the cysteine content of the extracellular NOTCH3 gene product. This molecular genetic signature of CADASIL has led to the hypothesis that structural abnormalities in the vascular smooth-muscle protein NOTCH3 trigger arterial degeneration, vascular protein accumulation, and cerebrovascular failure.

The developmental biology of genetic Notch disorders

Notch signaling regulates a vast array of crucial developmental processes. It is therefore not surprising that mutations in genes encoding Notch receptors or ligands lead to a variety of congenital disorders in humans. For example, loss of function of Notch results in Adams-Oliver syndrome, Alagille syndrome, spondylocostal dysostosis and congenital heart disorders, while Notch gain of function results in Hajdu-Cheney syndrome, serpentine fibula polycystic kidney syndrome, infantile myofibromatosis and lateral meningocele syndrome. Furthermore, structure-abrogating mutations in NOTCH3 result in CADASIL. Here, we discuss these human congenital disorders in the context of known roles for Notch signaling during development. Drawing on recent analyses by the exome aggregation consortium (EXAC) and on recent studies of Notch signaling in model organisms, we further highlight additional Notch receptors or ligands that are likely to be involved in human genetic diseases.

Clinical features and mutation spectrum in Chinese patients with CADASIL: A multicenter retrospective study

AIM

To characterize clinical features and mutation spectrum in Chinese patients with CADASIL.

METHODS

We collected 261 clinically suspected Chinese CADASIL patients from three hospitals located in different regions of China. Sanger sequencing is performed to screen the exons 2 to 24 of NOTCH3 gene. Clinical and genetic data were retrospectively studied. Haplotype analyses were performed in patients carrying p.Arg544Cys and p.Arg607Cys, respectively.

RESULTS

A total of 214 patients were finally genetically diagnosed as CADASIL, with 45 known NOTCH3 mutations and a novel c.1817G>T mutation. We found that patients carrying p.Arg607Cys or p.Arg544Cys mutation located in exon 11 occupied nearly 35% in our mutation spectrum. In retrospectively study of clinical data, we found a higher number of patients having cognitive impairment and a lower number of patients having migraine with aura. Furthermore, we identified that patients carrying mutations in exon 11 seemed to experience a later disease onset (p=6.8×10^-5 ). Additionally, a common haplotype was found in patients from eastern China carrying p.Arg607Cys, and the patients from Fujian carrying p.Arg544Cys shared the same haplotype with patients from Taiwan carrying p.Arg544Cys.

CONCLUSIONS

These findings broaden the mutational and clinical spectrum of CADASIL and provide additional evidences for the existence of founder effect in CADASIL patients.

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) as a model of small vessel disease: update on clinical, diagnostic, and management aspects

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common and best known monogenic small vessel disease. Here, we review the clinical, neuroimaging, neuropathological, genetic, and therapeutic aspects based on the most relevant articles published between 1994 and 2016 and on the personal experience of the authors, all directly involved in CADASIL research and care. We conclude with some suggestions that may help in the clinical practice and management of these patients.

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.

New mutations in the Notch3 gene in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL)

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a cerebrovascular small-vessel disease caused by stereotyped mutations in the Notch3 gene altering the number of cysteine residues.

METHODS

We directly sequenced exons 2-23 of the Notch3 gene in 30 unrelated Russian patients with clinical/neuroimaging picture suggestive of CADASIL. To confirm the pathogenicity of new nucleotide variants, we used the standard bioinformatics tools and screened 200 ethnically matched individuals as controls.

RESULTS

We identified 16 different point mutations in the Notch3 gene in 18 unrelated patients, including 4 new missense mutations (C194G, V252M, C338F, and C484G). All but two mutations affected the cysteine residue. The non-cysteine change V322M was shown to be associated with CADASIL-specific deposits of granular osmiophilic material in the vascular smooth-muscle cells, which confirmed the pathogenicity of this Notch3 variant. Two patients were shown to be compound-heterozygotes carrying two pathogenic Notch3 mutations. The disease was characterized by marked clinical variability, without evident phenotype-genotype correlations.

CONCLUSIONS

In our sample, 60% of Russian patients with 'clinically suspected' CADASIL received the definitive molecularly proven diagnosis. Careful assessment of genealogical, clinical, and neuroimaging data in patients with lacunar stroke can help selecting patients with a high probability of finding mutations on genetic screening.

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.

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.

Clinical variability of the cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy phenotype in two siblings of a large family showing the same mutation

A 44-year-old Albanian male was consulted and diagnosed with dementia. His magnetic resonance imaging suggested diffuse white matter changes. The suspicion of cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) was raised, and a genetic analysis confirmed such a suspicion through uncovering a pathogenic mutation at the level of exon 4 (c.475C>T) of chromosome 19. The patient came from a large family of 13 children, all of whom underwent clinical, genetic, and imaging examination. The pathogenic mutation was found present only in his eldest sister (50 years old), and she presented also very suggestive signs of CADASIL in her respective imaging study, but without any clinically significant counterpart. All other siblings were free from clinical and radiological signs of the disorder. Our opinion was that we were dealing with a mutation showing a very low level of penetrance, with only two siblings affected in a large Albanian family with 13 children.

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.

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephelopathy is an autosomal dominant disease affecting small vessels and often resulting in subcortical infarcts. A skin biopsy may facilitate its diagnosis as the cutaneous surface is much easier to sample than the central nervous system's tissue. Unfortunately, there is no effective treatment available today.

Hereditary cerebral small vessel diseases: a review

Cerebral microangiopathies are responsible of a great number of strokes. In the recent years advances in molecular genetics identified several monogenic conditions involving cerebral small vessels and predisposing to ischemic and/or hemorrhagic stroke and diffuse white matter disease leading to vascular dementia. Clinical features and diagnostic clues of these conditions, [cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), COL4A1-related cerebral small vessel diseases, autosomal dominant retinal vasculopathy with cerebral leukodystrophy (AD-RVLC), and Fabry's disease] are here reviewed. Albeit with variable phenotypes and with different defective genes, all these disorders produce arteriopathy and microvascular disintegration with changes in brain functions. Specific diagnostic tools are recommended, genetic analysis being the gold standard for the diagnosis.

Considerations on a mutation in the NOTCH3 gene sparing a cysteine residue: a rare polymorphism rather than a CADASIL variant

Some missense mutations and small deletions in the NOTCH3 gene, not involving cysteine residues, have been described in patients considered to be affected by paucisymptomatic CADASIL. However, the significance of such molecular variants is still unclear. We describe a 49-year-old woman with a CADASIL-like phenotype, carrying a novel cysteine-sparing mutation in exon 29 of the NOTCH3 gene, and discuss the possible pathogenetic role of this molecular variant. Even though atypical clinical and MRI findings make a diagnosis of CADASIL unlikely in this patient, our report nevertheless underlines the intriguing genotype-phenotype relationship in NOTCH3 mutations and the importance of functional investigation to ascertain the role of new NOTCH3 mutations in CADASIL pathogenesis.

The Cerebral Autosomal-Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL) Scale: a screening tool to select patients for NOTCH3 gene analysis

BACKGROUND AND PURPOSE

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) phenotype is highly variable, and, although the full clinical-neuroimaging picture may be suggestive of the disease, no characteristic is pathognomonic. Thus, a genetic test remains the diagnostic gold standard, but because it is costly and time-consuming, a pregenetic screening appears desirable. We aimed at developing the CADASIL scale, a screening tool to be applied in the clinical setting.

METHODS

A preliminary scale was created assigning weighted scores to common disease features based on their frequencies obtained in a pooled analysis of selected international CADASIL series. The accuracy of the scale versus the genetic diagnosis was tested with receiver operating characteristic analysis after the application of this scale to 61 CADASIL and 54 NOTCH3-negative patients (no pathogenic mutation on exons 2-23 of the NOTCH3 gene). To improve the scale accuracy, we then developed an ad hoc optimization algorithm to detect the definitive scale. A third group of 39 patients affected by sporadic small-vessel disease was finally included in the algorithm to evaluate the stability of the scale.

RESULTS

The cutoff score of the definitive CADASIL scale had a sensitivity of 96.7% and a specificity of 74.2%. This scale was robust to contamination of patients with sporadic small-vessel disease.

CONCLUSIONS

The CADASIL scale is a simple and sufficiently accurate screening tool to select patients with a high probability to be affected by the disease and therefore to be subjected to the genetic testing.

Identification of a known mutation in Notch 3 in familiar CADASIL in China

Background

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited disease leading to recurrent ischemic stroke and vascular dementia. Numerous mutations in the 23 exons of the NOTCH3 gene have been reported to cause CADASIL in Caucasian populations, but the full spectrum of genetic changes leading to this disease is yet to be known and, especially, very few reports are available on CADASIL in Asian populations.

Methods and Results

We genotyped members of a 5-generational Han Chinese family with CADASIL patients and identified an R133C mutation in the NOTCH3 gene. Clinical analysis demonstrated that the penetrance of the mutation was not complete. Five of the mutation carriers, not exposed to the known vascular risk factors, did not show any clinical feature of CADASIL, suggesting the importance of environmental factors to the development of this disease.

Conclusions

Members of a 5-generational Han Chinese family with CADASIL patients had an R133C mutation in the NOTCH3 gene but only individuals exposed to known vascular risk factors developed CADASIL.

Screening for NOTCH3 gene mutations among 151 consecutive Korean patients with acute ischemic stroke

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a single-gene disorder of cerebral small blood vessels caused by mutations in the NOTCH3 gene. The initial detection of CADASIL may be more difficult among Asian populations because common clinical phenotypes and neuroimaging findings are not frequently found in these populations. The purpose of this study was to screen the NOTCH3 gene for mutations among consecutive patients with acute ischemic stroke from our region in Korea.

METHODS

Between April 2008 and March 2009, 151 consecutive patients with acute ischemic stroke were screened for NOTCH3 mutations. All patients underwent a detailed clinical examination and structured interview for clinical symptoms and family history. We reviewed brain magnetic resonance imaging data from stroke patients to assess the severity of white-matter hyperintensity lesions, the number of cerebral microbleeds, and the number of lacunar infarctions. Polymerase chain reaction was used to screen exons 3, 4, 6, 11, and 18 of the NOTCH3 gene.

RESULTS

Among 151 consecutive patients with acute ischemic stroke, 6 patients (4.0%; 95% confidence interval [CI] 0.9-7.1) possessed a NOTCH3 gene mutation. All patients exhibited the same R544C mutation in exon 11. Four of these 6 patients presented with large artery atherosclerosis. The prevalence of CADASIL in patients with neuroimaging features consistent with advanced small-vessel disease was 36.0% (95% CI 8.0-64.8).

CONCLUSIONS

In this region, NOTCH3 gene mutations are frequently found in acute stroke patients who present with neuroimaging features consistent with advanced small-vessel disease.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

INTRODUCTION

Fast and precise diagnostics of the disease from the large group of adult leukoencephalopathy is difficult but responsible job, because the outcome of the disease is very often determined by its name. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by the mutation of Notch 3 gene on chromosome locus 19p13. Beside the brain arterioles being the main disease targets, extracerebral small blood vessels are affected by the pathological process. Clinically present signs are recurrent ischemic strokes and vascular dementia. CADASIL in its progressive form shows a distinctive pattern of pathological changes on MRI of endocranium. The diagnosis is confirmed by the presence of granular osmiophilic material (GOM) in histopathological skin biopsies.

CASE REPORTS

Two young adult patients manifested ischemic strokes of unknown etiology, cognitive deterioration, migraine and psychopathological phenomenology. MRI of endocranium pointed on CADASIL. Ultrastructural examination of skin biopsy proved the presence of GOM in the basal lamina and near smooth muscle cells of arteriole dermis leading to CADASIL diagnosis. The presence of GOM in histopathological preparation is 100% specific for CADASIL. The patients were not searched for mutation in Notch 3 gene on chromosome 19, because some other leukoencephalopathy was disregarded.

CONCLUSION

Suggestive clinical picture, distinctive finding of endocranium MRI, the presence of GOM by ultrastructural examination of histopathological skin biopsies are sufficient to confirm CADASIL diagnosis.

Vascular cognitive impairment: disease mechanisms and therapeutic implications

The prevalence of vascular cognitive impairment (VCI) is likely to increase as the population ages and cardiovascular disease survival improves. We provide an overview of the definition and disease mechanisms of VCI and present a systematic literature review of the current evidence for the pharmacologic and nonpharmacologic therapies used to treat the VCI symptoms of cognitive dysfunction or to modify VCI through primary and secondary prevention. The Cochrane Database of Systematic Reviews was searched from 2005 to October 2010 using the keywords "vascular dementia" or "vascular cognitive impairment and therapy." MEDLINE was searched for English-language articles published within the last 10 years using the combined Medical Subject Headings (MeSH) "therapeutics and dementia," "vascular" or "vascular cognitive impairment." Although cholinesterase inhibitors and memantine produce small cognitive improvements in patients with VCI, these drugs do not improve global clinical outcomes and have adverse effects and costs. Selective serotonin reuptake inhibitors and dihydropyridine calcium channel blockers may improve short-term cognitive function in patients with VCI. Anti-hypertensive therapy with an ACE inhibitor-based regimen and statins may prevent the major subtype of VCI known as poststroke cognitive decline. Clinical and effectiveness studies with long-term follow-up are needed to determine the benefits and risks of pharmacologic and nonpharmacologic therapies to prevent and treat VCI. Given its growing health, social, and economic burden, the prevention and treatment of VCI are critical priorities for clinical care and research.

NOTCH3 gene mutations in subjects clinically suspected of CADASIL

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebrovascular disease due to mutations involving loss or gain of a cysteine residue in the NOTCH3 gene. A cluster of mutations around exons 3 and 4 was originally reported. Identification of pathogenic mutation is important for diagnostic confirmation of the disease, however genetic counselling and testing of relatives at risk is critical in mutation carriers.

METHODS

Mutation analysis of the NOTCH3 gene was performed through direct sequencing in 140 patients with clinical suspicion of CADASIL. Patients underwent genetic counselling pre and post testing. The 2-23 exons containing all EGF-like domains were screened.

RESULTS

14 familial forms of the disease have been identified with 14 different causative mutations in exons 2, 3, 4, 5, 7, 10, 14, 19, 20 and 22 of the NOTCH3 gene; no pathogenetic mutations have been identified in exons 6 and 8; several genetic variations both in coding as well as in intronic regions were identified too.

CONCLUSIONS

Our data confirm the importance of screening the whole EGF-like domains region of NOTCH3 gene for the molecular diagnosis of CADASIL among the Italian population too. Moreover genetic variants different from loss or gain of a cysteine residue are identified and presented.

First report of a pathogenic mutation on exon 24 of the NOTCH3 gene in a CADASIL family

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetically transmitted small vessel disease clinically characterized by migraine, recurrent subcortical strokes, and cognitive and mood disorders. Pathogenic mutations are located on any of the exons of the NOTCH3 gene coding for epidermal-growth factor (EGF)-like repeats of the extracellular domain of the NOTCH3 receptor. Because the gene is large and the mutations cluster on some exons, many laboratories restrict the analysis to these exons. We report the first missense mutation involving exon 24 and causing CADASIL in a 64-year-old man. The patient was admitted to the hospital for a loss of consciousness accompanied by profuse sweating. On examination, some parkinsonian features were present. Over the last 4 years, he had developed postural instability and gait disturbances with repeated falls, behavioral disorders, and cognitive impairment. A diagnostic hypothesis of atypical parkinsonism had been advanced. The presence of multiple subcortical lacunar infarcts and leukoencephalopathy extended to the external capsule on cerebral MRI suggested the presence of CADASIL. The diagnosis was confirmed by finding a heterozygous mutation leading to a cysteine substitution on exon 24 of the NOTCH3 gene. One proband's brother, who had progressive gait disturbances, unilateral action tremor and bradykinesia, and an asymptomatic niece also resulted affected. This report underlines that when CADASIL is suspected the genetic analysis should be performed on all the NOTCH3 exons coding for EGF-like repeats including exon 24 and confirms that CADASIL may have heterogeneous phenotypes.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy in an Israeli family

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic form of hereditary cerebral microangiopathy, and is caused by over 170 different mutations in the NOTCH3 gene at locus 19p13.1-13.26. We report the first study of familial CADASIL in a 39-year-old Jewish woman and her mother who had died previously. The patient's investigations revealed a normal hemogram with no vascular risk factors or chronic disease. Lumbar puncture was normal. Cranial computed tomography scan revealed bilateral diffuse hypodensities in the subcortical white matter. Cranial magnetic resonance imaging showed hyperintense lesions in the cerebral white matter on T2-weighted images. On electron microscopy, a characteristic granular osmiophilic material was seen in the basement membrane surrounding the pericytes and smooth muscle cells in small-sized and medium-sized vessels. Molecular analysis of the NOTCH3 gene was performed with automatic sequencing of exon 3 and 4 (and intron-exon boundaries) showing a nucleotide c.268C > T substitution, leading to a pathogenic amino acid substitution of p.Arg90Cys, confirming a diagnosis of CADASIL. This mutation was also found in the patient's mother. Although the exact prevalence of CADASIL is not known, this disorder has been reported worldwide, and now including Jews, with a genotype and clinical phenotype similar to that in other ethnic groups.

CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a dominantly inherited small artery disease that leads to dementia and disability in mid-life. The clinical presentation of CADASIL is variable between and within affected families and is characterized by symptoms including migraine with aura, subcortical ischemic events, mood disturbances, apathy, and cognitive impairment. The mean age at onset of symptoms is 45 years, with variable duration of the disease ranging from 10 to 40 years. In 1996, linkage studies mapped and identified mutations in the NOTCH3 gene on chromosome 19 as causative in CADASIL. Head magnetic resonance imaging (MRI) is always abnormal in participants with NOTCH3 mutations after age 35. Magnetic resonance imaging shows on T2-weighted images or fluid attenuation inversion recovery (FLAIR) sequence, widespread areas of increased signal in the white matter associated with focal hyperintensities in basal ganglia, thalamus, and brainstem. The pathologic hallmark of CADASIL is the presence of electron-dense granules in the media of arterioles that can be identified by electron microscopic evaluation of skin biopsies.

CSF Biomarkers Profile in CADASIL-A Model of Pure Vascular Dementia: Usefulness in Differential Diagnosis in the Dementia Disorder

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is considered a model of pure vascular dementia (VD) because it occurs in young adults unlikely to have concomitant age and Alzheimer's Disease-(AD-) related pathology. CSF levels of β-amyloid 1-42 (Aβ42), total tau protein (t-tau), and phosphorylated tau-protein (p-tau), well accepted biomarkers of AD, were evaluated in 10 CADASIL patients, 22 AD patients, and 17 healthy age-matched subjects. Innotest β-amyloid 1-42, Innotest hTAU-Ag, and Innotest Phospho-tau 181p sandwich enzyme-linked immunoassay were used to determine CSF biomarkers levels. A case-control statistical analysis was carried out. CSF Aβ42 levels were significantly lower in CADASIL patients and considerable overlap with AD whereas t-tau and p-tau levels were normal and significantly different with respect to AD. A significant altered CSF biomarkers profile in a pure VD supports the use of CSF Aβ42, t-tau, and p-tau levels in the differential diagnosis of VD and AD.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: a genetic cause of cerebral small vessel disease

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a single-gene disorder of the cerebral small blood vessels caused by mutations in the Notch3 gene. The exact prevalence of this disorder was unknown currently, and the number of reported CADASIL families is steadily increasing as the clinical picture and diagnostic examinations are becoming more widely known. The main clinical manifestations are recurrent stroke, migraine, psychiatric symptoms, and progressive cognitive impairment. The clinical course of CADASIL is highly variable, even within families. The involvement of the anterior temporal lobe and the external capsule on brain magnetic resonance imaging was found to have high sensitivity and specificity in differentiating CADASIL from the much more common sporadic cerebral small-vessel disease (SVD). The pathologic hallmark of the disease is the presence of granular osmiophilic material in the walls of affected vessels. CADASIL is a prototype single-gene disorder that has evolved as a unique model for studying the mechanisms underlying cerebral SVD. At present, the incidence and prevalence of CADASIL seem to be underestimated due to limitations in clinical, neuroradiological, and genetic diagnoses of this disorder.

CADASIL: extended polymorphisms and mutational analysis of the NOTCH3 gene

CADASIL is a cerebrovascular disease caused by mutations in the NOTCH3 gene. Most mutations result in a gain or loss of cysteine residue in one of the 34 epidermal growth factor-like repeats in the extracellular domain of the Notch3 protein, thus sparing the number of cysteine residues. To date, more than 130 different mutations in the NOTCH3 gene have been reported in CADASIL patients, of which 95% are missense point mutations. Many polymorphisms have also been identified in the NOTCH3 coding sequence, some of them leading to amino acid substitutions. The aim of the present study was to analyze the NOTCH3 gene in a large group of patients affected by leukoencephalopathy and to investigate the presence of genetic variants. The molecular analysis revealed several nucleotide alterations. In particular, we identified 20 different mutations, 22 polymorphisms, and 8 genetic variants of unknown pathological significance never reported previously. We hope that this NOTCH3 gene mutational analysis, performed in such a significant number of unrelated and related patients affected by leukoencephalopathy, will help in molecular screening for the NOTCH3 gene, thus contributing to enlargement of the NOTCH3 gene variation database.

CADASIL management or what to do when there is little one can do

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare disease that leads to migraine, mood disorders, recurrent lacunar strokes and early vascular dementia. This autosomal-dominant condition is caused by mutations in the NOTCH3 gene and is characterized by degeneration of vascular smooth muscle cells. At present, no evidence-based treatment for CADASIL is available and only relief of symptoms can be offered to patients. This review focuses on an update of CADASIL management, based on the recent clinical and basic evidence, and discusses possible new treatment targets for CADASIL.

Distinct phenotypic and functional features of CADASIL mutations in the Notch3 ligand binding domain

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant small-vessel disease of the brain caused by mutations in the NOTCH3 receptor. The highly stereotyped nature of the mutations, which alter the number of cysteine residues within the epidermal growth factor-like repeats (EGFR), predicts that all mutations share common mechanisms. Prior in vitro assays and genetic studies in the mouse support the hypothesis that common mutations do not compromise canonical Notch3 function but instead convey a non-physiological and deleterious activity to the receptor through the unpaired cysteine residue. Intriguingly, in vitro studies predict that mutations located in the Delta/Serrate/LAG-2 ligand binding domain-(EGFR10-11) may result in a loss of Notch3 receptor function. However, the in vivo relevance and functional significance of this with respect to the pathogenic mechanisms and clinical expression of the disease remain largely unexplored. To ascertain, in vivo, the functional significance of EGFR10-11 mutations, we generated transgenic mice with one representative mutation (C428S) in EGFR10 of Notch3. These mice, like those with a common R90C mutation, developed characteristic arterial accumulation of Notch3 protein and granular osmiophilic material upon aging. By introducing the mutant C428S transgene into a Notch3 null background, we found that, unlike the R90C mutant protein, the C428S mutant protein has lost wild-type Notch3 activity and exhibited mild dominant-negative activity in three different biological settings. From a large prospectively recruited cohort of 176 CADASIL patients, we identified 10 patients, from five distinct pedigrees carrying a mutation in EGFR10 or 11. These mutations were associated with significantly higher Mini-Mental State Examination and Mattis Dementia Rating Scale scores (P < 0.05), when compared with common mutations. Additionally, we found a strong effect of this genotype on the burden of white matter hyperintensities (P < 0.01). Collectively, these results highlight distinctive functional and phenotypic features of EGFR10-11 mutations relative to the common CADASIL mutations. Our findings are compatible with the hypothesis that EGFR10-11 mutations cause the disease through the same gain of novel function as the common mutations, and lead us to propose that reduced Notch3 signalling acts as a modifier of the CADASIL phenotype.

Population-specific spectrum of NOTCH3 mutations, MRI features and founder effect of CADASIL in Chinese

BACKGROUND AND PURPOSE

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disorder caused by NOTCH3 mutations and characterized by recurrent subcortical infarctions, dementia and leukoencephalopathy. So far, most clinical, molecular and neuroimaging information has come from Caucasians. Therefore, we investigated the spectrum of NOTCH3 mutations and MRI features in CADASIL patients of Chinese origin on Taiwan.

METHODS

Mutational analysis of NOTCH3 exons 2 to 23 by direct nucleotide sequencing was performed in patients with clinically suspected CADASIL. MRI findings were retrospectively evaluated and scored using a modified Schelten's scale.

RESULTS

Nine different point mutations of NOTCH3 were identified in 21 unrelated patients. Intriguingly, 47.6 % were in exon 11, and 19 % in each of exon 4 and 18. R544C was very common and present in all patients with a mutation in exon 11. Many patients with NOTCH3 R544C share the same haplotype linked to the mutation using markers D19S929 and D19S411, which flank the NOTCH3. The sensitivity of T2-weighted MRI detecting anterior temporal abnormality was only 42.9 %. Furthermore, the neuroimaging evidence of intracerebral hemorrhage (ICH) was present in 23.8 % of the 21 patients.

CONCLUSIONS

A population-specific mutational spectrum of CADASIL was found in the Chinese patients on Taiwan. The Chinese patients carrying NOTCH3 R544C may descend from a common ancestor. Anterior temporal hyperintensity on T2-weighted MRI may not be a sensitive marker for CADASIL. ICH is a relatively common manifestation of CADASIL in East Asians, especially in the presence of hypertension.

Congruence between NOTCH3 mutations and GOM in 131 CADASIL patients

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary subcortical vascular dementia. It is caused by mutations in NOTCH3 gene, which encodes a large transmembrane receptor Notch3. The key pathological finding is the accumulation of granular osmiophilic material (GOM), which contains extracellular domains of Notch3, on degenerating vascular smooth muscle cells (VSMCs). GOM has been considered specifically diagnostic for CADASIL, but the reports on the sensitivity of detecting GOM in patients' skin biopsy have been contradictory. To solve this contradiction, we performed a retrospective investigation of 131 Finnish, Swedish and French CADASIL patients, who had been adequately examined for both NOTCH3 mutation and presence of GOM. The patients were examined according to the diagnostic practice in each country. NOTCH3 mutations were assessed by restriction enzyme analysis of specific mutations or by sequence analysis. Presence of GOM was examined by electron microscopy (EM) in skin biopsies. Biopsies of 26 mutation-negative relatives from CADASIL families served as the controls. GOM was detected in all 131 mutation positive patients. Altogether our patients had 34 different pathogenic mutations which included three novel point mutations (p.Cys67Ser, p.Cys251Tyr and p.Tyr1069Cys) and a novel duplication (p.Glu434_Leu436dup). The detection of GOM by EM in skin biopsies was a highly reliable diagnostic method: in this cohort the congruence between NOTCH3 mutations and presence of GOM was 100%. However, due to the retrospective nature of this study, exact figure for sensitivity cannot be determined, but it would require a prospective study to exclude possible selection bias. The identification of a pathogenic NOTCH3 mutation is an indisputable evidence for CADASIL, but demonstration of GOM provides a cost-effective guide for estimating how far one should proceed with the extensive search for a new or an uncommon mutations among the presently known over 170 different NOTCH3 gene defects. The diagnostic skin biopsy should include the border zone between deep dermis and upper subcutis, where small arterial vessels of correct size are located. Detection of GOM requires technically adequate biopsies and distinction of true GOM from fallacious deposits. If GOM is not found in the first vessel or biopsy, other vessels or additional biopsies should be examined.