CADASIL with Atypical Clinical Symptoms, Magnetic Resonance Imaging, and Novel Mutations: Two Case Reports and a Review of the Literature

SNP and Structural Study of the Notch Superfamily Provides Insights and Novel Pharmacological Targets against the CADASIL Syndrome and Neurodegenerative Diseases

The evolutionary conserved Notch signaling pathway functions as a mediator of direct cell-cell communication between neighboring cells during development. Notch plays a crucial role in various fundamental biological processes in a wide range of tissues. Accordingly, the aberrant signaling of this pathway underlies multiple genetic pathologies such as developmental syndromes, congenital disorders, neurodegenerative diseases, and cancer. Over the last two decades, significant data have shown that the Notch signaling pathway displays a significant function in the mature brains of vertebrates and invertebrates beyond neuronal development and specification during embryonic development. Neuronal connection, synaptic plasticity, learning, and memory appear to be regulated by this pathway. Specific mutations in human Notch family proteins have been linked to several neurodegenerative diseases including Alzheimer's disease, CADASIL, and ischemic injury. Neurodegenerative diseases are incurable disorders of the central nervous system that cause the progressive degeneration and/or death of brain nerve cells, affecting both mental function and movement (ataxia). There is currently a lot of study being conducted to better understand the molecular mechanisms by which Notch plays an essential role in the mature brain. In this study, an in silico analysis of polymorphisms and mutations in human Notch family members that lead to neurodegenerative diseases was performed in order to investigate the correlations among Notch family proteins and neurodegenerative diseases. Particular emphasis was placed on the study of mutations in the Notch3 protein and the structure analysis of the mutant Notch3 protein that leads to the manifestation of the CADASIL syndrome in order to spot possible conserved mutations and interpret the effect of these mutations in the Notch3 protein structure. Conserved mutations of cysteine residues may be candidate pharmacological targets for the potential therapy of CADASIL syndrome.

Determining the etiology of cerebral stroke: from the most prevalent to rare causes

Cerebral stroke remains the leading cause of death and disability worldwide as well as in Ukraine. After a cerebral stroke, there is an increased risk of a new cerebral stroke (9‒15 % within 1 year), and about a quarter of all cerebral stroke are recurrent. Up to 80 % of recurrent cerebral stroke can be avoided through lifestyle modifications (healthy diet, sufficient amount of physical activity, normalization of body weight, cessation of smoking and alcohol abuse) and control of chronic diseases such as hypertension, diabetes, hyperlipidemia and atrial fibrillation. The key to effective secondary prevention is determining the etiology of cerebral stroke, which requires a primary examination in all cases and a number of additional tests as needed. The most common causes of ischemic cerebral stroke are cardiogenic embolism, atherosclerosis of the large cerebral arteries (macroangiopathy), and brain small vessels disease (microangiopathy), but approximately 1/3 of cerebral stroke have other, rear, determined cause or the cause remains unknown despite the appropriate workup (cryptogenic cerebral stroke). In the review, we discuss modern approaches to ischemic cerebral stroke classification and determination of their etiology, from the most prevalent to the rarest causes. A careful search for the cause of cerebral stroke is particularly important in young patients (aged 18 to 50 years) with a high life expectancy. We have reviewed in detail the possibilities of screening for subclinical atrial fibrillation by long-term cardiac monitoring with implantable devices and the diagnosis of monogenetic causes of cerebral stroke, with a particular focus on Fabry disease, for which there is an effective treatment.

Monogenic Causes of Strokes

Strokes are the main cause of death and long-term disability worldwide. A stroke is a heterogeneous multi-factorial condition, caused by a combination of environmental and genetic factors. Monogenic disorders account for about 1% to 5% of all stroke cases. The most common single-gene diseases connected with strokes are cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) Fabry disease, mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS) and a lot of single-gene diseases associated particularly with cerebral small-vessel disease, such as COL4A1 syndrome, cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), and Hereditary endotheliopathy with retinopathy, nephropathy, and stroke (HERNS). In this article the clinical phenotype for the most important single-gene disorders associated with strokes are presented. The monogenic causes of a stroke are rare, but early diagnosis is important in order to provide appropriate therapy when available.

Ataxia Associated with CADASIL: a Pathology-Confirmed Case Report and Literature Review

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is primarily characterized by migraine, stroke, mood disturbances, and cognitive decline. Ataxia has seldom been reported as a presenting symptom. Here, we review reports of CADASIL presenting as ataxia and compare these to the first pathologically confirmed case of CADASIL presenting with progressive ataxia. A 50-year-old woman presented with progressive truncal ataxia. Brain magnetic resonance imaging (MRI) revealed white matter hyperintensities in the bilateral anterior temporal lobes, external capsules, and periventricular areas, but not the cerebellum. Electron microscopy of skin biopsy material revealed multiple granular osmiophilic materials. Genetic testing confirmed a c.4552C > A mutation in exon 25 of the NOTCH3 gene. CADASIL is a rare cause of progressive ataxia, and only four cases of CADASIL presenting with ataxia have been reported in the literature. We also discuss the possible pathophysiology of cerebellar ataxia associated with CADASIL.

Leukoaraiosis and acute ischemic stroke

Ischaemic stroke is characterized by high morbidity, high disability rate, high mortality and high recurrence rate, which can have a grave impact on the quality of life of the patients and consequently becomes an economic burden on their families and society. With the developments in imaging technology in recent years, patients with acute cerebral infarction are predominantly more likely to be diagnosed with leukoaraiosis (LA). LA is a common degenerative disease of the nervous system, which is related to cognitive decline, depression, abnormal gait, ischaemic stroke and atherosclerosis. The aetiology of LA is not clear and there is no gold standard for imaging assessment. Related studies have shown that LA has an adverse effect on the prognosis of cerebral infarction, but some experts have contrary beliefs. Hence, we undertook the present review of the literature on the mechanism and the effect of LA on the prognosis of patients with acute ischaemic stroke.

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

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

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

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

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

Prevalence and Atypical Clinical Characteristics of NOTCH3 Mutations Among Patients Admitted for Acute Lacunar Infarctions

Objectives: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary small vessel disease, with reported frequencies of 2-5/100,000 individuals. Recently, it has been reported that some patients with NOTCH3 gene mutations show atypical clinical symptoms of CADASIL. Assuming that CADASIL is underdiagnosed in some cases of lacunar infarction, this study was designed to examine the prevalence of NOTCH3 gene mutations in the patients at highest risk who were admitted for lacunar infarctions.

Methods: From January 2011 to April 2018, 1,094 patients with lacunar infarctions were admitted to our hospital, of whom 31 patients without hypertension but with white matter disease (Fazekas scale 2 or 3) were selected and genetically analyzed for NOTCH3 gene mutations (Phase 1). Furthermore, 54 patients, who were 60 years or younger, were analyzed for NOTCH3 mutations (Phase 2). NOTCH3 exons 2–24, which encode the epidermal growth factor-like repeat domain of the NOTCH3 receptor, were analyzed for mutations by direct sequencing of genomic DNA.

Results: Three patients presented NOTCH3 p.R75P mutations: two in the Phase 1 and one in the Phase 2 cohort. Among patients aged 60 years or younger and those without hypertension but with moderate-to-severe white matter lesions, the carrier frequency of p.R75P was 3.5% (3/85), which was significantly higher than that in the Japanese general population (4.7KJPN) (odds ratio [95% CI] = 58.2 [11.6–292.5]). All three patients with NOTCH3 mutations had family histories of stroke, and the average patient age was 51.3 years. All three patients also showed white matter lesions in the external capsule but not in the temporal pole. The CADASIL and CADASIL scale-J scores of the three patients were 6, 17, 7 (mean, 10.0) and 13, 20, 10 (mean, 14.3), respectively.

Conclusion: Among patients hospitalized for lacunar infarctions, the p.R75P prevalence may be higher than previously estimated. The NOTCH3 p.R75P mutation may be underdiagnosed in patients with early-onset lacunar infarctions due to the atypical clinical and neuroimaging features of CADASIL. Early-onset, presence of family history of stroke, external capsule lesions, and absence of hypertension may help predict underlying NOTCH3 mutations despite no temporal white matter lesions.