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First Report of Arg587Cys Mutation of Notch3 Gene in Two Chinese Families with CADASIL
ARTICLE IN PRESS
Case Studies
First Report of Arg587Cys Mutation of Notch3 Gene in Two Chinese Families with CADASIL Jinsong You, MD, PhD, Shaojun Liao, MD, Foming Zhang, Zhaohui Ma, MD, PhD, and Guifu Li, MD
MD, PhD,
Objective: To explore Notch3 mutation sites of Chinese patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Methods: Direct sequencing of all exons in Notch3 gene was performed on 12 unrelated suspected CADASIL cases from mainland China. Result: A missense p.Arg587Cys (1759C>T) mutation in exon 11 was identified in 2 patients through genetic analysis. Conclusion: Chinese patients with CADASIL of R587C mutation in exon 11 was firstly reported. Key Words: CADASIL—mutations—Notch3 gene—stroke. © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.
Introduction Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare autosomal dominant hereditary cerebrovascular disease, a small vessel disease of the brain that is nonatherosclerotic as well as nonamyloid angiopathy. It is caused by mutations in the Notch3 gene on chromosome 19p13.2-13.1.1 Clinically the syndrome is manifested as recurrent ischemic attacks, either transient ischemic attack or stroke, migraine with aura, progressive cognitive decline, and psychiatric symptoms.1,2 Multiple lacunar infarcts associated with extensive white matter hyperintensities showed From the Department of Neurology, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China. Received August 1, 2016; revision received September 1, 2016; accepted September 11, 2016. Grant support: This study was supported by the Natural Science Foundation of Guangdong (No. 10151040701000064). Address correspondence to Jinsong You, MD, PhD, Department of Neurology, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, 111 Dade Road, Guangzhou, Guangdong 510120, People’s Republic of China. E-mail: [email protected]. 1052-3057/$ - see front matter © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2016.09.014
on brain magnetic resonance imaging (MRI), especially high-signal lesions in the anterior temporal pole on T2-images that have high specificity for the diagnosis of CADASIL.3,4 Granular osmiophilic material (GOM) deposits in the tunica media of the degenerating vascular smooth muscle cells, the pathological hallmarks of this disease, are proposed to be the first diagnostic method, although with limited sensitivity.5,6 To date, more than 200 mutations of Notch3 have been reported in CADASIL patients (data from The Human Gene Mutation Database (HGMD)). To our knowledge, the Arg587Cys Notch3 mutation at exon 11, which had been identified in the Korean families in 2006, has not been reported in other populations. Herein, we report 2 Chinese families affected with CADASIL who have the Arg587Cys mutation of Notch3 gene at exon 11 and we characterize their disease in terms of comprehensive clinical and neuroimaging studies.
Case Report Case 1 The index patient, from Guangdong Province, is a 62year-old man noticed for walking slowly and having a dull reaction for 3 months. He was initially brought to medical attention because the said symptoms developed progressively in 6 days, accompanied by cognitive
Journal of Stroke and Cerebrovascular Diseases, Vol. ■■, No. ■■ (), 2016: pp ■■–■■
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ARTICLE IN PRESS J. YOU ET AL.
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Figure 1. Brain magnetic resonance images of Case 1. MR-Flair (A-D) showed multiple lacunar infarcts and diffuse leukoencephalopathy. Significant abnormalities were not found in magnetic resonance angiography (E).
impairment, which is characterized by difficulty in his activities of daily living such as opening the door with his key and using his cell phone to make calls. He had no remarkable medical history of hypertension, diabetes mellitus, cerebrovascular diseases, and mental disorder. His mother died of stroke and pneumonia aged 76 years old and presented with dementia in her late years. His father died of chronic obstructive pulmonary disease at 80 years old. And only the little sister, among their four siblings, experienced mild cognitive disturbances since juvenile age, without deterioration. His neurological examination was unremarkable except for right central facial paralysis, brisk tendon reflexes in limbs, the right pathological sign being positive, and moderate memory disturbance (his Mini-Mental State Examination [MMSE] score was 18 and cognitive impairment defined as MMSE≤26). Computed tomography scans revealed the presence of hemorrhage in the left thalamus (3 mL approximately). Brain MRI showed multiple subcortical lacunar infarcts in the pontine, bilateral basal ganglia, the right thalamus, bilateral corona radiate, centrum semiovale bilaterally, and frontal-parietal lobe (Fig 1, A-D), and magnetic resonance angiography was normal (Fig 3, E). Following up in 2015, the old multifocal microbleeds were found in the left thalamus, bilateral cerebellar hemisphere, and basal ganglia by susceptibility-weighted imaging (SWI) in brain MRI (Fig 2, A-E). On the basis of the clinical manifestations and neuroimaging data, a diagnosis of CADASIL was sus-
pected. Genetic testing detected the disease-causing mutation, p.Arg587Cys (1759C>T), in exon 11 of Notch3, and a diagnosis of CADASIL was assigned. However, the patient’s little sister with mild cognitive disturbances did not carry any mutation in Notch3, and no other unaffected family members requested genetic testing for Notch3 mutations.
Case 2 The proband, from Guangdong Province similarly, is a 60-year-old man who had suffered from a 7-year history of recurrent dizziness or vertigo. He presented to our department with little benefit from the therapy of improving cerebral circulation, and with an onset of memory disturbance for nearly 6 months, progressive for about 10 days. Additional symptoms such as progressive mood disturbance are observed as well. The patient had a 6-year history of hypertension that is controlled perfectly, and was in absence of clear histories of diabetes mellitus and other disorders. The mother of the patient died of lung cancer at 75, and the father died of myocardial infarction at 68, He has a younger brother and a son who have no history of migraine, stroke, transient ischemic attack, and memory problem. Salient findings of his neurologic examination included brisk tendon reflexes in the left limbs and suspected bilateral positive pathological sign. His performance on the MMSE was mildly impaired (a score of 22 out of 30). The Selfrating Anxiety Scale and Self-rating Depression Scale,
Figure 2. Susceptibility-weighted imaging of Case 1 (A-E) revealed old hemorrhage in the left thalamus and multifocal microbleeds both in the brainstem and the basal ganglia.
ARTICLE IN PRESS ARG587CYS MUTATION OF NOTCH3 IN CHINESE FAMILIES WITH CADASIL
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Figure 3. Brain magnetic resonance images of Case 2. MR-Flair (A-D) showed multiple lacunar infarcts and diffuse leukoencephalopathy. Significant abnormalities were not found in magnetic resonance angiography (E).
respectively, showed moderate anxiety (an original score of 55 and a standard score of 69) and moderate depression (an original score of 47 and a standard score of 59). Brain MRI typically revealed multiple subcortical lacunar infarcts, affected bilateral basal ganglia, thalamus, corona radiate, centrum semiovale, and deep white matter of frontal parietal temporal occipital (Fig 3, A-D). SWI showed multiple areas of low-signal lesions over bilateral cerebellar hemisphere, bilateral frontotemporal lobe, the right parietal lobe, and bilateral thalami, indicative of old multiple microbleeds (Fig 4, A-E). Significant abnormalities were not found in magnetic resonance angiography (Fig 3, E). Neuroimaging data and medical history led us to raise suspicion of CADASIL. Notch3 analysis revealed the same p.1759C>T mutation on exon 11 of this patient, and the diagnosis was confirmed. Unfortunately, his younger brother and son without any symptoms of stroke refused the correlative examination of CADASIL, including brain MRI and genetic test.
Discussion CADASIL is one of the most common hereditary forms of stroke, of which vascular smooth muscle cell degeneration caused by the Notch 3 mutation plays a critical role in the pathogenetic mechanism. Notch3 containing 33 exons encodes the Notch3 protein, a single-pass transmembrane protein of 2321 amino acids, that is predominantly expressed in vascular smooth muscle cells
Figure 4.
in adults.7 The ectodomain of Nctch3 consists of 34 epidermal growth factor-like repeat (EGFR) domains, and each of the EGFR domains contains exactly 6 highly conserved cysteine residues, binding 3 cysteine-cysteine disulfide bonds.8 It was suggested that the unpaired cysteine residues caused by Notch3 mutations might result in a misfolding of the protein through disruption of the disulfide bonds. This abnormal structure could then alter maturation, targeting, and degradation, and affect the function of the Notch3 receptor finally. Using polymerase chain reaction-directed sequence analysis, we identified a missense p.Arg587Cys (1759C>T) mutation of the Notch3 from the 2 unrelated patients. The mutation was caused by a 1759C>T substitution in exon 11, introducing an additional cysteine residue between the first and second cysteine residues in the EGFR 15. Korean families with CADASIL who have R587C were firstly identified in 2006.9 The reported patients typically present with stroke, dementia, as well as mood disturbances, but with absence of clear histories of migraine with aura. Their brain MRI was characterized by multiple subcortical lacunar infarcts and diffuse leukoencephalopathy. In our study, migraine with aura, which is considered to be the earliest clinical manifestation among Caucasian CADASIL patients, was not found in the reported cases. This is consistent with previous studies that migraine presents relatively infrequent incidences in CADASIL patients from Asian populations.9,10 In agreement with previous finding, the first case in our study suffered from symptomatic intracranial hemorrhage, and
Susceptibility-weighted imaging (A-E) of Case 2 revealed multifocal microbleeds in the brainstem, cerebellum, and basal ganglia bilaterally.
ARTICLE IN PRESS J. YOU ET AL.
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both the patients showed asymptomatic microbleeds in cerebellum, brainstem, and basal ganglia bilaterally, however, there was no typical white matter lesions involving the medial temporal lobe in MRI. Which means the diversity of clinical symptoms and neuroimaging in CADASIL patients. The largest study, Notch3 mutational spectrum in 33 pedigrees with CADASIL from mainland China, indicates that the mutation hotspots are located in exons 4 (55%) and 3 (30%).11 In 21 CADASIL patients from Taiwan, NOTCH3 mutations resided most frequently in exon 11 (47.6%), followed by exons 4 and 8 (both 19%); moreover, R544C was present in all patients with a mutation in exon 11.12,13 As a result of the vast population in China and the population migration in history, we speculate that CADASIL mutations in mainland China are derived from more than one ancestor. The higher frequency of mutations in exon 11 from the Guangdong population found in the present study and the Notch3 R544C mutation that had been reported here both potentially suggest that there is distribution discrepancy of Notch3 mutations between population from Guangdong and Min-Tai and the northerners.
References 1. Joutel A, Corpechot C, Ducros A, et al. Notch3 mutations in CADASIL, a hereditary adult-onset condition causing stroke and dementia. Nature 1996;383:707-710. 2. Chabriat H, Vahedi K, Iba-Zizen MT, et al. Clinical spectrum of CADASIL: a study of 7 families. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Lancet 1995;346:934-939.
3. Dichgans M, Mayer M, Uttner I, et al. The phenotypic spectrum of CADASIL: clinical findings in 102 cases. Ann Neurol 1998;44:731-739. 4. Chabriat H, Levy C, Taillia H, et al. Patterns of MRI lesions in CADASIL. Neurology 1998;51:452-457. 5. Ruchoux MM, Guerouaou D, Vandenhaute B, et al. Systemic vascular smooth muscle cell impairment in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Acta Neuropathol 1995;89:500-512. 6. Markus HS, Martin RJ, Simpson MA, et al. Diagnostic strategies in CADASIL. Neurology 2002;59:1134-1138. 7. Joutel A, Andreux F, Gaulis S, et al. The ectodomain of the Notch3 receptor accumulates within the cerebrovasculature of CADASIL patients. J Clin Invest 2000;105:597-605. 8. Chabriat H, Joutel A, Dichgans M, et al. Cadasil. Lancet Neurol 2009;8:643-653. 9. Kim Y, Choi EJ, Choi CG, et al. Characteristics of CADASIL in Korea: a novel cysteine-sparing Notch3 mutation. Neurology 2006;66:1511-1516. 10. Wilder-Smith E, Shen Y, Ng YK, et al. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Chinese family: clinical, radiological and skin biopsy features. J Clin Neurosci 2004;11:304-307. 11. Wang Z, Yuan Y, Zhang W, et al. NOTCH3 mutations and clinical features in 33 mainland Chinese families with CADASIL. J Neurol Neurosurg Psychiatry 2011;82:534-539. 12. Lee YC, Liu CS, Chang MH, et al. Population-specific spectrum of NOTCH3 mutations, MRI features and founder effect of CADASIL in Chinese. J Neurol 2009;256:249-255. 13. Liao Y-C, Hsiao C-T, Fuh J-L, et al. Characterization of CADASIL among the Han Chinese in Taiwan: distinct genotypic and phenotypic profiles. PLoS ONE 2015; 10:e0136501.
Case Studies
First Report of Arg587Cys Mutation of Notch3 Gene in Two Chinese Families with CADASIL Jinsong You, MD, PhD, Shaojun Liao, MD, Foming Zhang, Zhaohui Ma, MD, PhD, and Guifu Li, MD
MD, PhD,
Objective: To explore Notch3 mutation sites of Chinese patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Methods: Direct sequencing of all exons in Notch3 gene was performed on 12 unrelated suspected CADASIL cases from mainland China. Result: A missense p.Arg587Cys (1759C>T) mutation in exon 11 was identified in 2 patients through genetic analysis. Conclusion: Chinese patients with CADASIL of R587C mutation in exon 11 was firstly reported. Key Words: CADASIL—mutations—Notch3 gene—stroke. © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.
Introduction Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare autosomal dominant hereditary cerebrovascular disease, a small vessel disease of the brain that is nonatherosclerotic as well as nonamyloid angiopathy. It is caused by mutations in the Notch3 gene on chromosome 19p13.2-13.1.1 Clinically the syndrome is manifested as recurrent ischemic attacks, either transient ischemic attack or stroke, migraine with aura, progressive cognitive decline, and psychiatric symptoms.1,2 Multiple lacunar infarcts associated with extensive white matter hyperintensities showed From the Department of Neurology, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, People’s Republic of China. Received August 1, 2016; revision received September 1, 2016; accepted September 11, 2016. Grant support: This study was supported by the Natural Science Foundation of Guangdong (No. 10151040701000064). Address correspondence to Jinsong You, MD, PhD, Department of Neurology, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, 111 Dade Road, Guangzhou, Guangdong 510120, People’s Republic of China. E-mail: [email protected]. 1052-3057/$ - see front matter © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2016.09.014
on brain magnetic resonance imaging (MRI), especially high-signal lesions in the anterior temporal pole on T2-images that have high specificity for the diagnosis of CADASIL.3,4 Granular osmiophilic material (GOM) deposits in the tunica media of the degenerating vascular smooth muscle cells, the pathological hallmarks of this disease, are proposed to be the first diagnostic method, although with limited sensitivity.5,6 To date, more than 200 mutations of Notch3 have been reported in CADASIL patients (data from The Human Gene Mutation Database (HGMD)). To our knowledge, the Arg587Cys Notch3 mutation at exon 11, which had been identified in the Korean families in 2006, has not been reported in other populations. Herein, we report 2 Chinese families affected with CADASIL who have the Arg587Cys mutation of Notch3 gene at exon 11 and we characterize their disease in terms of comprehensive clinical and neuroimaging studies.
Case Report Case 1 The index patient, from Guangdong Province, is a 62year-old man noticed for walking slowly and having a dull reaction for 3 months. He was initially brought to medical attention because the said symptoms developed progressively in 6 days, accompanied by cognitive
Journal of Stroke and Cerebrovascular Diseases, Vol. ■■, No. ■■ (), 2016: pp ■■–■■
1
ARTICLE IN PRESS J. YOU ET AL.
2
Figure 1. Brain magnetic resonance images of Case 1. MR-Flair (A-D) showed multiple lacunar infarcts and diffuse leukoencephalopathy. Significant abnormalities were not found in magnetic resonance angiography (E).
impairment, which is characterized by difficulty in his activities of daily living such as opening the door with his key and using his cell phone to make calls. He had no remarkable medical history of hypertension, diabetes mellitus, cerebrovascular diseases, and mental disorder. His mother died of stroke and pneumonia aged 76 years old and presented with dementia in her late years. His father died of chronic obstructive pulmonary disease at 80 years old. And only the little sister, among their four siblings, experienced mild cognitive disturbances since juvenile age, without deterioration. His neurological examination was unremarkable except for right central facial paralysis, brisk tendon reflexes in limbs, the right pathological sign being positive, and moderate memory disturbance (his Mini-Mental State Examination [MMSE] score was 18 and cognitive impairment defined as MMSE≤26). Computed tomography scans revealed the presence of hemorrhage in the left thalamus (3 mL approximately). Brain MRI showed multiple subcortical lacunar infarcts in the pontine, bilateral basal ganglia, the right thalamus, bilateral corona radiate, centrum semiovale bilaterally, and frontal-parietal lobe (Fig 1, A-D), and magnetic resonance angiography was normal (Fig 3, E). Following up in 2015, the old multifocal microbleeds were found in the left thalamus, bilateral cerebellar hemisphere, and basal ganglia by susceptibility-weighted imaging (SWI) in brain MRI (Fig 2, A-E). On the basis of the clinical manifestations and neuroimaging data, a diagnosis of CADASIL was sus-
pected. Genetic testing detected the disease-causing mutation, p.Arg587Cys (1759C>T), in exon 11 of Notch3, and a diagnosis of CADASIL was assigned. However, the patient’s little sister with mild cognitive disturbances did not carry any mutation in Notch3, and no other unaffected family members requested genetic testing for Notch3 mutations.
Case 2 The proband, from Guangdong Province similarly, is a 60-year-old man who had suffered from a 7-year history of recurrent dizziness or vertigo. He presented to our department with little benefit from the therapy of improving cerebral circulation, and with an onset of memory disturbance for nearly 6 months, progressive for about 10 days. Additional symptoms such as progressive mood disturbance are observed as well. The patient had a 6-year history of hypertension that is controlled perfectly, and was in absence of clear histories of diabetes mellitus and other disorders. The mother of the patient died of lung cancer at 75, and the father died of myocardial infarction at 68, He has a younger brother and a son who have no history of migraine, stroke, transient ischemic attack, and memory problem. Salient findings of his neurologic examination included brisk tendon reflexes in the left limbs and suspected bilateral positive pathological sign. His performance on the MMSE was mildly impaired (a score of 22 out of 30). The Selfrating Anxiety Scale and Self-rating Depression Scale,
Figure 2. Susceptibility-weighted imaging of Case 1 (A-E) revealed old hemorrhage in the left thalamus and multifocal microbleeds both in the brainstem and the basal ganglia.
ARTICLE IN PRESS ARG587CYS MUTATION OF NOTCH3 IN CHINESE FAMILIES WITH CADASIL
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Figure 3. Brain magnetic resonance images of Case 2. MR-Flair (A-D) showed multiple lacunar infarcts and diffuse leukoencephalopathy. Significant abnormalities were not found in magnetic resonance angiography (E).
respectively, showed moderate anxiety (an original score of 55 and a standard score of 69) and moderate depression (an original score of 47 and a standard score of 59). Brain MRI typically revealed multiple subcortical lacunar infarcts, affected bilateral basal ganglia, thalamus, corona radiate, centrum semiovale, and deep white matter of frontal parietal temporal occipital (Fig 3, A-D). SWI showed multiple areas of low-signal lesions over bilateral cerebellar hemisphere, bilateral frontotemporal lobe, the right parietal lobe, and bilateral thalami, indicative of old multiple microbleeds (Fig 4, A-E). Significant abnormalities were not found in magnetic resonance angiography (Fig 3, E). Neuroimaging data and medical history led us to raise suspicion of CADASIL. Notch3 analysis revealed the same p.1759C>T mutation on exon 11 of this patient, and the diagnosis was confirmed. Unfortunately, his younger brother and son without any symptoms of stroke refused the correlative examination of CADASIL, including brain MRI and genetic test.
Discussion CADASIL is one of the most common hereditary forms of stroke, of which vascular smooth muscle cell degeneration caused by the Notch 3 mutation plays a critical role in the pathogenetic mechanism. Notch3 containing 33 exons encodes the Notch3 protein, a single-pass transmembrane protein of 2321 amino acids, that is predominantly expressed in vascular smooth muscle cells
Figure 4.
in adults.7 The ectodomain of Nctch3 consists of 34 epidermal growth factor-like repeat (EGFR) domains, and each of the EGFR domains contains exactly 6 highly conserved cysteine residues, binding 3 cysteine-cysteine disulfide bonds.8 It was suggested that the unpaired cysteine residues caused by Notch3 mutations might result in a misfolding of the protein through disruption of the disulfide bonds. This abnormal structure could then alter maturation, targeting, and degradation, and affect the function of the Notch3 receptor finally. Using polymerase chain reaction-directed sequence analysis, we identified a missense p.Arg587Cys (1759C>T) mutation of the Notch3 from the 2 unrelated patients. The mutation was caused by a 1759C>T substitution in exon 11, introducing an additional cysteine residue between the first and second cysteine residues in the EGFR 15. Korean families with CADASIL who have R587C were firstly identified in 2006.9 The reported patients typically present with stroke, dementia, as well as mood disturbances, but with absence of clear histories of migraine with aura. Their brain MRI was characterized by multiple subcortical lacunar infarcts and diffuse leukoencephalopathy. In our study, migraine with aura, which is considered to be the earliest clinical manifestation among Caucasian CADASIL patients, was not found in the reported cases. This is consistent with previous studies that migraine presents relatively infrequent incidences in CADASIL patients from Asian populations.9,10 In agreement with previous finding, the first case in our study suffered from symptomatic intracranial hemorrhage, and
Susceptibility-weighted imaging (A-E) of Case 2 revealed multifocal microbleeds in the brainstem, cerebellum, and basal ganglia bilaterally.
ARTICLE IN PRESS J. YOU ET AL.
4
both the patients showed asymptomatic microbleeds in cerebellum, brainstem, and basal ganglia bilaterally, however, there was no typical white matter lesions involving the medial temporal lobe in MRI. Which means the diversity of clinical symptoms and neuroimaging in CADASIL patients. The largest study, Notch3 mutational spectrum in 33 pedigrees with CADASIL from mainland China, indicates that the mutation hotspots are located in exons 4 (55%) and 3 (30%).11 In 21 CADASIL patients from Taiwan, NOTCH3 mutations resided most frequently in exon 11 (47.6%), followed by exons 4 and 8 (both 19%); moreover, R544C was present in all patients with a mutation in exon 11.12,13 As a result of the vast population in China and the population migration in history, we speculate that CADASIL mutations in mainland China are derived from more than one ancestor. The higher frequency of mutations in exon 11 from the Guangdong population found in the present study and the Notch3 R544C mutation that had been reported here both potentially suggest that there is distribution discrepancy of Notch3 mutations between population from Guangdong and Min-Tai and the northerners.
References 1. Joutel A, Corpechot C, Ducros A, et al. Notch3 mutations in CADASIL, a hereditary adult-onset condition causing stroke and dementia. Nature 1996;383:707-710. 2. Chabriat H, Vahedi K, Iba-Zizen MT, et al. Clinical spectrum of CADASIL: a study of 7 families. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Lancet 1995;346:934-939.
3. Dichgans M, Mayer M, Uttner I, et al. The phenotypic spectrum of CADASIL: clinical findings in 102 cases. Ann Neurol 1998;44:731-739. 4. Chabriat H, Levy C, Taillia H, et al. Patterns of MRI lesions in CADASIL. Neurology 1998;51:452-457. 5. Ruchoux MM, Guerouaou D, Vandenhaute B, et al. Systemic vascular smooth muscle cell impairment in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Acta Neuropathol 1995;89:500-512. 6. Markus HS, Martin RJ, Simpson MA, et al. Diagnostic strategies in CADASIL. Neurology 2002;59:1134-1138. 7. Joutel A, Andreux F, Gaulis S, et al. The ectodomain of the Notch3 receptor accumulates within the cerebrovasculature of CADASIL patients. J Clin Invest 2000;105:597-605. 8. Chabriat H, Joutel A, Dichgans M, et al. Cadasil. Lancet Neurol 2009;8:643-653. 9. Kim Y, Choi EJ, Choi CG, et al. Characteristics of CADASIL in Korea: a novel cysteine-sparing Notch3 mutation. Neurology 2006;66:1511-1516. 10. Wilder-Smith E, Shen Y, Ng YK, et al. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Chinese family: clinical, radiological and skin biopsy features. J Clin Neurosci 2004;11:304-307. 11. Wang Z, Yuan Y, Zhang W, et al. NOTCH3 mutations and clinical features in 33 mainland Chinese families with CADASIL. J Neurol Neurosurg Psychiatry 2011;82:534-539. 12. Lee YC, Liu CS, Chang MH, et al. Population-specific spectrum of NOTCH3 mutations, MRI features and founder effect of CADASIL in Chinese. J Neurol 2009;256:249-255. 13. Liao Y-C, Hsiao C-T, Fuh J-L, et al. Characterization of CADASIL among the Han Chinese in Taiwan: distinct genotypic and phenotypic profiles. PLoS ONE 2015; 10:e0136501.