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CADASIL

[Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy]


Authors:
Saskia AJ Lesnik Oberstein, MD, PhD
Elles MJ Boon, PhD
Martin Dichgans, MD, PhD

Initial Posting:
15 March 2000

Last Update:
21 November 2006

 

Summary

Disease characteristics.  CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is characterized by a history of migraine headaches (30%-40% of individuals), mid-adult (30s-60s) onset of cerebrovascular disease progressing to dementia, and diffuse white matter lesions and subcortical infarcts on neuroimaging.

Diagnosis/testing.  The pathologic hallmark of CADASIL is electron-dense granules in the media of arterioles that can often be identified by electron microscopic (EM) evaluation of skin biopsies. NOTCH3 is the only gene known to be associated with CADASIL. More than 90% of individuals have mutations in the NOTCH3 gene. Molecular genetic testing is available on a clinical basis.

Management.  Treatment of manifestations: Supportive care (practical help, emotional support, and counseling) is appropriate for affected individuals and their families. Agents to avoid: Angiography and anticoagulants may provoke cerebrovascular accidents; smoking increases the risk of stroke.

Genetic counseling.  CADASIL is inherited in an autosomal dominant manner. Most affected individuals have an affected parent; de novo mutations are rare. Each child of an affected person is at a 50% risk of inheriting the mutation and developing signs of the disease. Prenatal testing is possible; however, requests for prenatal testing of typically adult-onset disorders are uncommon.


Diagnosis

Clinical Diagnosis

There are no generally accepted diagnostic criteria for CADASIL.

The presenting symptoms, age at onset, and disease progression in CADASIL vary. Typical signs and symptoms:

Frequent and diagnostically important signs on brain magnetic resonance imaging (MRI) [Auer et al 2001 , O'Sullivan et al 2001]:

A family history consistent with autosomal dominant inheritance supports the diagnosis [Dichgans et al 1998 , Razvi et al 2005a] but is not required [Joutel et al 2000].

Brain imaging.  Imaging abnormalities in CADASIL evolve as the disease progresses [van den Boom et al 2003 , Singhal et al 2005]. MRI white matter hyperintensities, although sometimes very subtle, are consistently visualized from age 21 years onward [Lesnik Oberstein 2003]. In individuals age 20-30 years with a pathogenic mutation, distinctive white matter hyperintensities first appear in the anterior temporal lobes, when the rest of the white matter, except for periventricular caps, appears unaffected [Lesnik Oberstein 2003 , van den Boom et al 2003]. In the course of the disease, the load of white matter hyperintensity lesions increases, eventually coalescing to the point where, in some elderly individuals, normal-appearing white matter is barely distinguishable [Chabriat et al 1998].

In symptomatic individuals, white matter hyperintensities are symmetrically distributed and located in the periventricular and deep white matter. Within the white matter, the frontal lobe is the site with the highest lesion load, followed by the temporal and parietal lobes [Chabriat et al 1999 , Auer et al 2001 , O'Sullivan et al 2001].

Additional findings:

Pathology.  The diagnosis can be confirmed by ultrastructural analysis of small arterioles obtained, for example, by skin biopsy [Goebel et al 1997 , Ruchoux & Maurage 1997]. Electron microscopy shows characteristic granular osmiophilic material within the vascular media close to smooth muscle cells. These changes are highly specific for CADASIL but the sensitivity of biopsy is limited and depends on the quality of the sample and skills of the pathologist [Schultz et al 1999].

NOTCH3 immunostaining, a means of confirming the diagnosis, is quite sensitive, specific, and more straightforward than electronmicroscopy, but not yet commercially available [Joutel et al 2001 , Lesnik Oberstein 2003].

Molecular Genetic Testing

GeneReviews designates a molecular genetic test as clinically available only if the test is listed in the GeneTests Laboratory Directory by either a US CLIA-licensed laboratory or a non-US clinical laboratory. GeneTests does not verify laboratory-submitted information or warrant any aspect of a laboratory's licensure or performance. Clinicians must communicate directly with the laboratories to verify information. —ED.

Gene.   NOTCH3 is the only gene currently known to be associated with CADASIL.

Molecular genetic testing: Clinical uses

Molecular genetic testing: Clinical method

Sequence analysis.  Most mutations in the NOTCH3 gene in individuals with CADASIL are located in exon 4, followed by exons 3, 5, 6, and 11 [Joutel et al 1997 ; Lesnik Oberstein et al 1999 ; Markus et al 2002 ; Peters, Opherk, Bergmann et al 2005]. Geographic variations have been described, showing exon 3 to be the second most common mutation site in French, British, and German persons [Joutel et al 1997 ; Markus et al 2002 ; Peters, Opherk, Bergmann et al 2005], while exon 11 is frequently affected in Dutch persons [Lesnik Oberstein 2003].

The mutation detection rate ranges from 57% to 96% in individuals with well-defined or biopsy-proven CADASIL [Markus et al 2002 ; Peters, Opherk, Bergmann et al 2005].

Possible explanations for the discrepancies between different studies in the location of the mutations and the mutation detection rate include the following:

Table 1 summarizes molecular genetic testing for this disorder.
Table 1. Molecular Genetic Testing Used in CADASIL
Test Method
Mutations Detected
Mutation Detection Rate
Test Availability
Estimated >95%  1
Clinical
Testing
1. When all epidermal growth factor-like (EGFL) repeats are sequenced

Interpetation of test results.  Homozygous mutations have been described in CADASIL [Tuominen 2001 ; Lesnik Oberstein, unpublished observation].

For issues to consider in interpretation of sequence analysis results, click here.

Testing Strategy for a Proband

NOTCH3 molecular genetic testing should begin with exons 2-6 and 11, followed by complete sequencing of all EGFL repeats.

Genetically Related (Allelic) Disorders

No other phenotype is known to be caused by mutations in the NOTCH3 gene.

NOTCH3 over-expression has been described in ovarian cancer [Park et al 2006] and neuroblastoma [van Limpt et al 2005].

Clinical Description

Natural History

CADASIL is a microangiopathy mainly affecting the brain. The presenting symptoms, age at onset, and disease progression in CADASIL vary.

Stroke-like episodes.  Transient ischemic attacks (TIAs) and stroke, the most frequent presentation, are found in about 85% of symptomatic individuals [Chabriat, Vahedi et al 1995 ; Dichgans et al 1998]. Strokes related to small vessel pathology are clearly the main manifestation of the disease.

Mean age at onset for ischemic episodes is around 46 years (range: ~19-67 years) [Opherk et al 2004].

Ischemic episodes typically present as a classic lacunar syndrome (pure motor stroke, ataxic hemiparesis/dysarthria-clumsy hand syndrome, pure sensory stroke, sensorimotor stroke), but other lacunar syndromes (brainstem or hemispheric) are also observed. Ischemic episodes are often recurrent, leading to severe disability with gait disturbance, urinary incontinence, and pseudobulbar palsy.

Strokes involving the territory of a large artery have occasionally been reported [Rubio et al 1997]. However, those observations may be coincidental.

Cognitive deficits and dementia.  Cognitive deficits, the second most frequent feature, are observed in about 60% of symptomatic individuals. They may start as early as age 35 years. About 75% of affected individuals develop dementia [Dichgans et al 1998 , Opherk et al 2004].

The pattern of cognitive dysfunction is characterized by deficits in executive function (timed measures and measures of error monitoring), verbal fluency, and memory with benefit from clues [Peters, Opherk, Danek et al 2005]. Cognitive dysfunction is accompanied by a narrowing of the field of interest. In most cases, cognitive decline is slowly progressive with additional stepwise deterioration. Amberla et al (2004) observed deterioration of working memory and executive function in individuals with NOTCH3 mutations in the prestroke phase, and infer that cognitive decline may start insidiously before the onset of symptomatic ischemic episodes.

Migraine.  Migraine occurs in about 40% of individuals with CADASIL, with the first attack occurring at a mean age of 26 years. Ninety percent of individuals with migraine have migraine with aura [Dichgans et al 1998]. In some families with CADASIL, migraine with aura is the most prominent symptom.

Reversible acute encephalopathy.  Acute encephalopathy has been described in about a dozen individuals, with confusion, headache, pyrexia, seizures, and coma, sometimes leading to death [Chabriat, Vahedi et al 1995 ; Feuerhake et al 2002 ; Schon et al 2003].

Psychiatric disorders.  Thirty percent of individuals with CADASIL experience psychiatric disturbance, varying from personality changes to severe depression [Dichgans et al 1998]. Whether these disturbances are primary or reactive is not yet clear. However, individuals with CADASIL presenting with psychiatric problems have been described [Lalith-Kumar & Mahr 1997 , Leyhe et al 2005 , Nakamura et al 2005].

Epilepsy.  Epilepsy is present in 10% of individuals with CADASIL and presents at middle age [Dichgans et al 1998].

Pregnancy.  A retrospective study of 25 women found an increased frequency of ischemic symptoms (TIA and stroke) during pregnancy, particularly in those older than age 30 years [Roine et al 2005].

Other

Genotype-Phenotype Correlations

Although some studies describe phenotype-genotype correlations, the genotype cannot be used to predict the phenotype in individuals with CADASIL [Singhal et al 2004]. Even within a single family, the age of onset, disease severity, and disease progression can vary significantly.

Dichgans et al (1999) found no influence of the NOTCH3 genotype on quantitative MRI variables.

Opherk et al (2004) found the p.C117F mutation associated with a lower age at death and the p.C174K mutation with a lower of age of onset for stroke and death.

Lesnik Oberstein et al (2001) detected an increased number of cerebral microbleeds in individuals with the p.R153C mutation.

Homozygous mutations have been described in CADASIL [Tuominen 2001 ; Lesnik Oberstein, unpublished observation]. The phenotype of individuals homozygous for NOTCH3 mutations falls within the CADASIL spectrum.

Penetrance

Penetrance of the disease is probably 100%, but expression varies in age of onset, severity of the clinical symptoms, and progression of the disease.

Anticipation

Anticipation, the phenomenon in which increasing disease severity or decreasing age of onset is observed in successive generations, was suggested in a family with a p.S180C mutation reported by Nakamura et al (2005). No other occurrence of anticipation in persons with CADASIL has been reported.

Nomenclature

Previous descriptions of families with "hereditary multi-infarct dementia," "chronic familial vascular encephalopathy," and "familial subcortical dementia" represent early reports of CADASIL [Sourander & Walinder 1977 , Stevens et al 1977 , Davous & Fallet-Bianco 1991].

Prevalence

Based on a small registry for CADASIL in the area of Glasgow, Razvi and colleagues (2005b) calculated a mutation carrier frequency of 1.98 per 100,000 adults.

While the majority of published data have come from Europe, CADASIL has been observed on all continents.

A founder effect has been reported for Finnish individuals with CADASIL [Mykkanen et al 2004].

Differential Diagnosis

For current information on availability of genetic testing for disorders included in this section, see GeneTests Laboratory Directory. —ED.

The differential diagnosis of CADASIL includes multiple sclerosis (MS) [Vahedi et al 1996], sporadic small vessel disease including Binswanger's disease [Caplan 1995], and primary angiitis of the nervous system [Williamson et al 1999]. The clinical characteristics and MRI abnormalities in these conditions may resemble those of CADASIL. The presence of temporopolar MRI lesions, the absence of optic nerve and spinal cord involvement, the absence of oligoclonal bands in the cerebrospinal fluid, and the absence of hypertension are critical in this regard [Dichgans et al 1999].

Other inherited disorders in the differential diagnosis include Fabry disease , CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy) [Yanagawa et al 2002], MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes), and some forms of leukodystrophy. These disorders can be distinguished from CADASIL by the associated clinical signs, MRI, mode of inheritance, and appropriate laboratory investigations.

CADASIL should also be considered in any young person who has migraine with aura in conjunction with multiple white matter lesions on MRI [Glastone & Dodick 2005].

Management

Evaluations at Initial Diagnosis to Establish the Extent of Disease

Treatment of Manifestations

Supportive care in the form of practical help, emotional support, and counseling are appropriate for affected individuals and their families.

No specific support group exists for individuals with CADASIL, but information relevant to Huntington disease and Alzheimer disease can well be applied to CADASIL.

Prevention of Primary Manifestations

Smoking increases the risk of stroke in individuals with CADASIL and should be avoided [Singhal et al 2004].

Surveillance

The interval at which individuals with CADASIL should be seen for follow-up depends on the severity and type of symptoms and the needs of the patients and their care givers.

Agents/Circumstances to Avoid

Angiography and anticoagulants are contraindicated in CADASIL as they may provoke cerebrovascular accidents [Dichgans & Petersen 1997 , Lesnik Oberstein et al 2001].

Smoking increases the risk of stroke in individuals with CADASIL and should be avoided [Singhal et al 2004].

Therapies Under Investigation

A double-blind placebo-controlled trial evaluating the efficacy and safety of Donepezil HCL in individuals with CADASIL who have cognitive impairment has just been completed. The data of this trial are currently being analyzed.

Search ClinicalTrials.gov for access to information on clinical studies for a wide range of diseases and conditions.

Other

Cross-sectional and longitudinal studies suggest that disease progression is faster in individuals with CADASIL who have increased blood pressure [Peters et al 2004 , Holtmannspotter et al 2005 , Peters et al 2006]. However, no controlled data are available regarding the effect of antihypertensive treatment on disease progression.

Based on the experience with stroke in general, many neurologists prescribe salicylates. Whether these have any effect on preventing stroke in individuals with CADASIL has not been studied.

Genetic Counseling

Genetic counseling is the process of providing individuals and families with information on the nature, inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. The following section deals with genetic risk assessment and the use of family history and genetic testing to clarify genetic status for family members. This section is not meant to address all personal, cultural, or ethical issues that individuals may face or to substitute for consultation with a genetics professional. To find a genetics or prenatal diagnosis clinic, see the GeneTests Clinic Directory. —ED.

Mode of Inheritance

CADASIL is inherited in an autosomal dominant manner.

Risk to Family Members

Parents of a proband

Note: Although most individuals diagnosed with CADASIL have an affected parent, the family history may appear to be negative because of failure to recognize the disorder in family members, early death of the parent before the onset of symptoms, or late onset of the disease in the affected parent.

Sibs of a proband

Offspring of a proband

Related Genetic Counseling Issues

Testing of at-risk asymptomatic adults.  Testing of at-risk asymptomatic adults is available using the same techniques described in Molecular Genetic Testing . This testing is not useful in predicting age of onset, severity, type of symptoms, or rate of progression in asymptomatic individuals. Routine testing of asymptomatic at-risk individuals with nonspecific or equivocal symptoms is predictive testing, not diagnostic testing. When testing at-risk individuals, an affected family member should be tested first to confirm that the mutation is identifiable by currently available techniques.

It is appropriate to follow the guidelines published for presymptomatic testing for Huntington disease . At-risk asymptomatic adult family members may seek testing in order to make personal decisions regarding reproduction, financial matters, and career planning. Others may have different motivations, including simply the "need to know." Testing of asymptomatic at-risk adult family members usually involves pretest interviews in which the motives for requesting the test, the individual's knowledge of CADASIL, and the possible impact of positive and negative test results are assessed. Those seeking testing should be counseled about possible problems that they may encounter with regard to health, life, and disability insurance coverage, employment and educational discrimination, and changes in social and family interaction. Other issues to consider are implications for the at-risk status of other family members. Informed consent should be procured and records kept confidential. Individuals with a positive test result need arrangements for long-term follow-up and evaluations.

Testing for at-risk asymptomatic individuals during childhood.  Consensus holds that individuals younger than age 18 years at risk for adult-onset disorders should not have testing in the absence of symptoms. The principal arguments against testing asymptomatic individuals during childhood are that it removes their choice to know or not know this information, it raises the possibility of stigmatization within the family and in other social settings, and it could have serious educational and career implications. Symptomatic individuals who are younger than age 18 years usually benefit from having a specific diagnosis established. (See also the National Society of Genetic Counselors resolution on genetic testing of children and the American Society of Human Genetics and American College of Medical Genetics points to consider : ethical, legal, and psychosocial implications of genetic testing in children and adolescents.)

Considerations in families with an apparent de novo mutation.  When neither parent of a proband with an autosomal dominant condition has the disease-causing mutation or clinical evidence of the disorder, it is likely that the proband has a de novo mutation. However, possible non-medical explanations including alternate paternity or undisclosed adoption could also be explored.

Family planning.  The optimal time for determination of genetic risk and discussion of the availability of prenatal testing is before pregnancy. Similarly, decisions about testing to determine the genetic status of at-risk asymptomatic family members are best made before pregnancy.

DNA banking.  DNA banking is the storage of DNA (typically extracted from white blood cells) for possible future use. Because it is likely that testing methodology and our understanding of genes, mutations, and diseases will improve in the future, consideration should be given to banking DNA, particularly in situations in which the sensitivity of currently available testing is less than 100%. See DNA Banking for a list of laboratories offering this service.

Prenatal Testing

Prenatal testing for pregnancies at increased risk is possible by analysis of DNA extracted from fetal cells obtained by amniocentesis usually performed at about 15-18 weeks' gestation or chorionic villus sampling (CVS) at about ten to 12 weeks' gestation. The disease-causing mutation of an affected family member must be identified before prenatal testing can be performed. Prenatal diagnosis of CADASIL has been reported [Milunsky et al 2005 ; Lesnik Oberstein, unpublished data].

Note: Gestational age is expressed as menstrual weeks calculated either from the first day of the last normal menstrual period or by ultrasound measurements.

Preimplantation genetic diagnosis (PGD) may be available for families in which the disease-causing mutation has been identified in an affected family member. For laboratories offering PGD, see Testing .

Molecular Genetics

Information in the Molecular Genetics tables may differ from that in the text; tables may contain more recent information. —ED.


Molecular Genetics of CADASIL
Gene Symbol
Chromosomal Locus
Protein Name
NOTCH3
19p13.2-p13.1
Neurogenic locus notch homolog protein 3
Data are compiled from the following standard references: Gene symbol from HUGO; chromosomal locus, locus name, critical region, complementation group from OMIM; protein name from Swiss-Prot.

OMIM Entries for CADASIL
 125310 
CEREBRAL ARTERIOPATHY, AUTOSOMAL DOMINANT, WITH SUBCORTICAL INFARCTS AND LEUKOENCEPHALOPATHY; CADASIL
 600276 
NOTCH, DROSOPHILA, HOMOLOG OF, 3; NOTCH3


Genomic Databases for CADASIL
Gene Symbol
Entrez Gene
HGMD
NOTCH3
For a description of the genomic databases listed, click here.
Note:  HGMD requires registration.


Normal allelic variants: The NOTCH3 gene consists of 33 exons spanning roughly 7 kb.

Pathologic allelic variants: The majority of sequence alterations in the NOTCH3 gene are missense mutations (95%), characteristically leading to the loss or gain of a cysteine residue in one of the EGF-like domains of the protein encoded by the NOTCH3 gene [Dichgans et al 2001]. This results in an uneven number of cysteine residues in the given domain, most likely modifying the tertiary structure of the protein [Joutel et al 1997]. A splice-site mutation and five small deletions, also resulting in an uneven number of cysteine residues, have been described [Joutel & Tournier-Lasserve 1998 , Federico et al 2005]. Almost 90% of mutations occurred in exons 2-6 [Peters, Opherk, Bergmann et al 2005], but there are regional differences [Federico et al 2005]. (For more information, see Genomic Databases table above.)

Normal gene product: Members of the NOTCH gene family encode evolutionarily conserved transmembrane receptors, which are involved in cell fate specification during development [Weinmaster 1997]. The protein encoded by the NOTCH3 gene consists of 2321 amino acids. It has an extracellular ligand-binding domain of 34 epidermal growth factor-like repeats, traverses the membrane once, and has an intracellular domain required for signal transduction [Weinmaster 1997].

Abnormal gene product: The functional consequences of NOTCH3 mutations in the abnormal protein are unknown. The mutations lead to loss or gain of a cysteine residue. This has led to the hypotheses that either the mutations affect folding by disrupting disulphide bonding of the cysteine residues or they could lead to increased reactivity of the NOTCH3 protein. Another proposal is that the receptor cannot be properly internalized resulting in enhanced ligand binding or, alternatively, toxic effects [Louvi et al 2006].

Resources

GeneReviews provides information about selected national organizations and resources for the benefit of the reader. GeneReviews is not responsible for information provided by other organizations. -ED.

  • National Library of Medicine Genetics Home Reference
    CADASIL

  • United Leukodystrophy Foundation (ULF)
    2304 Highland Drive
    Sycamore IL 60178
    Phone: 800-728-5483; 815-895-3211
    Fax: 815-895-2432
    Email: office@ulf.org
    www.ulf.org

  • Alzheimer's Association
    The Alzheimer’s Association has material on their site to assist in caretaking issues for adult with dementia.
    www.alz.org

  • Huntington's Disease Society of America (HDSA)
    HDSA has material on their site to assist in caretaking issues for adult onset progressive neurologic diseases.
    www.hdsa.org

  Resources Printable Copy

References

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