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

A novel report of Cys1298Gly mutation in exon 24 of NOTCH3 gene in a Chinese family with CADASIL

OBJECTIVES

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is the most common monogenic hereditary small cerebral vessel disease, which is caused by mutation of the neurogenic locus notch homolog protein 3 gene (NOTCH3). The exon 24 encodes EGF-like repeats, variants on this exon are rare. Here, we report a novel heterozygous variant c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 gene in a 57-year-old Chinese woman.

MATERIALS AND METHODS

We present a patient with clinical manifestations, laboratory examination and imaging reveal suspicion of CADASIL. The family and genetic test and pathological examination were performed.

RESULTS

Magnetic resonance imaging revealed diffuse leukoencephalopathy with hyperintense signals in the bilateral temporal poles, periventricular white matter, centrum semiovale, basal ganglia, frontal and parietal cortex and subcortical areas bilaterally. Molecular Genetic testing identified a heterozygous variant c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 gene. Her brother and his son were confirmed as subclinical carriers of the variant. The skin biopsy was negative, but the pathologic role of this mutation is predicted by using the DynaMut database and results showed the stability of the NOTCH gene is decreased.

CONCLUSIONS

To the best of our knowledge, this is the second case of exon 24 mutations reported from China and the variant of c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 has not been reported so far. Our report broadens the mutation spectrum of the NOTCH3 gene in CADASIL.

Association between NOTCH3 gene and Parkinson's disease based on whole-exome sequencing

Objective

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebral small vessel disease caused by mutations in the NOTCH3 gene. Previous studies have established a link between NOTCH3 variants and Parkinson's disease (PD) in terms of neuropathology and clinical characteristics. In this study, we aimed to explore the role of NOTCH3 gene in PD in a large Chinese cohort.

Methods

A total of 1,917 patients with early-onset or familial PD and 1,652 matched controls were included. All variants were divided into common or rare types by minor allele frequency (MAF) at a threshold of 0.01 (MAF > 0.01 into common variants and others into rare variants). Common variants were subjected to single-variant tests by PLINK, then gene-based analyses were used for rare variants with the optimized sequence kernel association test (SKAT-O). For genotype-phenotype correlation assessment, regression models were conducted to compare clinical features between the studied groups.

Results

Three common variants (rs1044006, rs1043997, and rs1043994) showed a nominal protective effect against PD. However, none of these SNPs survived Bonferroni correction. The results in the validation cohort revealed a significant but opposite association between these variants and PD. The gene-based analyses of rare variants showed no significant associations of NOTCH3 with PD. Although we did not find significant associations in the following genotype-phenotype analysis, the higher clinical scores of motor symptoms in NOTCH3-variant carriers were of interest.

Conclusion

Our results indicated that NOTCH3 gene may not play an important role in the early-onset or familial PD of Chinese population.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 1: Genetic Disorders

We selected several "imaging pearls" presented during the Movement Disorder Society (MDS) Video Challenge for this review. While the event, as implicated by its name, was video-centered, we would like to emphasize the important role of imaging in making the correct diagnosis. We divided this anthology into two parts: genetic and acquired disorders. Genetic cases described herein were organized by the inheritance pattern and the focus was put on the imaging findings and differential diagnoses. Despite the overlapping phenotypes, certain described disorders have pathognomonic MRI brain findings that would provide either the "spot" diagnosis or result in further investigations leading to the diagnosis. Despite this, the diagnosis is often challenging with a broad differential diagnosis, and hallmark findings may be present for only a limited time.

Case Report: Progressive Asymmetric Parkinsonism Secondary to CADASIL Without Dementia

Parkinsonism is a rare phenotype of cerebral autosomal dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL), all of which involve cognitive decline. Normal cognition has not been reported in previous disease studies. Here we report the case of a 60-year-old female patient with a 2-year history of progressive asymmetric parkinsonism. On examination, she showed severe parkinsonism featuring bradykinesia and axial and limb rigidity with preserved cognition. Magnetic resonance imaging (MRI) revealed white matter hyperintensity in the external capsule and periventricular region. Dopaminergic response was limited. A missense mutation c.1630C>T (p.R544C) on the NOTCH3 gene was identified on whole-exome sequencing, which confirmed the diagnosis of vascular parkinsonism secondary to CADASIL. A diagnosis of CADASIL should be considered in asymmetric parkinsonism without dementia. Characteristic MRI findings support the diagnosis.

Neurosurgical Management of Lateral Meningocele Syndrome: A Clinical Update for the Pediatric Neurosurgeon

BACKGROUND

Lateral meningocele syndrome (LMS) is an exceedingly rare connective tissue disease with phenotypic anomalies similar to those seen in Marfan syndrome, Ehler-Danlos syndrome, and Loeys-Dietz syndrome. However, this syndrome is invariably associated with the presence of multiple lateral thoracolumbar spinal meningoceles: a distinct point of phenotypic divergence from other connective tissue disorders. The etiopathogenesis of this syndrome has recently been linked to truncating mutations within exon 33 of NOTCH3. Despite numerous reports, neurosurgical management of multiple spinal meningoceles remains poorly defined in the literature. We conducted a literature review to provide insight into the nosology, clinical significance, and neurosurgical management strategies of this distinct connective tissue disorder.

SUMMARY

Our literature search revealed 11 articles (16 cases) of LMS, which included 9 males and 7 females, belonging to 14 different families. Half of these cases underwent genetic screening: all of which were discovered to exhibit a truncating mutation within exon 33 of NOTCH3. All patients exhibited multiple lateral thoracolumbar spinal meningoceles with craniofacial dysmorphisms. Other clinical characteristics included pathologic changes in spine morphology, Chiari I malformation, syringomyelia, hydrocephalus, and tethered cord. Operative management of multiple spinal meningoceles in LMS is complicated by the presence of such coexisting structural neurologic pathologies, which may alter cerebrospinal fluid flow dynamics and, ultimately, impact operative intervention. Key Messages: LMS is an exceedingly rare connective tissue disorder with severe spinal dural involvement. Neurosurgical management of multiple spinal meningoceles is complex, which is further complicated by the presence of coexisting neuropathology, such as pathologic transformation of spine morphology and Chiari I malformation. Patients with a connective tissue disorder phenotype found to have multiple spinal meningoceles on imaging studies may benefit from evaluation by a medical geneticist and a pediatric neurosurgeon.

A Japanese Case of CADASIL with a Rare Mutation in Exon 24 of the NOTCH3 Gene

A 50-year-old man with a family history of stroke and depression slowly developed brain lesions. Magnetic resonance imaging revealed hyperintense lesions in the diffuse white matter, external capsules, and temporal poles on T2-weighted imaging. A heterozygous mutation c.3879C>G in exon 24 of the NOTCH3 gene (p.Cys1293Trp) was detected, confirming a diagnosis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Exon 24 mutations are rather rare and this represents the first Japanese case of CADASIL.

Clinical, familial, and neuroimaging features of CADASIL-like patients

OBJECTIVES

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited small vessel disease caused by NOTCH3 mutations. There are no clinical and neuroimaging findings pathognomonic of the disease. The aim of this paper was to provide a description of a group of NOTCH3-negative patients with a phenotype closely resembling that of CADASIL.

MATERIALS AND METHODS

We performed NOTCH3 analysis (exons 2-23) in 117 probands because of a clinician's suspicion of CADASIL. The CADASIL scale, a recently developed tool that allows to better select patients for NOTCH3 analysis, was retrospectively applied to NOTCH3-negative patients; the patient subgroup that scored higher than the screening cutoff for CADASIL was defined as CADASIL-like.

RESULTS

Thirty-four CADASIL-like patients (mean age at onset 57.8 years [52.1-63.4], 50% males) were identified. Compared with 25 patients with CADASIL for clinical, familial, and neuroimaging features, only the following variables were significantly (α level <0.05) different in frequency between patients with CADASIL and CADASIL-like patients: a positive family history for stroke at age ≤ 60 years, more frequent in patients with CADASIL, and hypertension, more frequent in CADASIL-like patients.

CONCLUSIONS

Our experience highlights the growing number of patients presenting with a high suspicion of a cerebral small vessel disease with an autosomal dominant pattern of inheritance and a phenotype closely similar to that of CADASIL but without NOTCH3 mutations. This group remains to be characterized from the genetic point of view. The role of other genes or NOTCH3 alterations on exons other than 2-23 or introns has to be further assessed.

Migraine genetics: current findings and future lines of research

In the last two decades, migraine research has greatly advanced our current knowledge of the genetic contributions and the pathophysiology of this common and debilitating disorder. Nonetheless, this knowledge still needs to grow further and to translate into more effective treatments. To date, several genes involved in syndromic and monogenic forms of migraine have been identified, allowing the generation of animal models which have significantly contributed to current knowledge of the mechanisms underlying these rare forms of migraine. Common forms of migraine are instead posing a greater challenge, as they may most often stem from complex interactions between multiple common genetic variants, with environmental triggers. This paper reviews our current understanding of migraine genetics, moving from syndromic and monogenic forms to oligogenic/polygenic migraines most recently addressed with some success through genome-wide association studies. Methodological issues in study design and future perspectives opened by biomarker research will also be briefly addressed.

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.

Parkinsonism is a late, not rare, feature of CADASIL: a study on Italian patients carrying the R1006C mutation

BACKGROUND AND PURPOSE

To describe parkinsonism as a clinical manifestation of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

METHODS

We report 5 patients carrying the R1006C mutation in the exon 19 of NOTCH3 gene. All cases presented late onset, slowly progressive parkinsonism, not responsive to l-dopa. We performed brain MRI and (123)I-FP-CIT SPECT in all and in 3 additional patients carrying the same mutation but without parkinsonism. Four patients with parkinsonism underwent myocardial (123)I-meta-iodobenzylguanidine scintigraphy.

RESULTS

In all patients, brain MRI showed widespread ischemic lesions in the periventricular white matter, the internal and external capsules, the basal ganglia, and thalami. (123)I-FP-CIT SPECT showed symmetrical or asymmetrical reduction of tracer uptake in the putamen, with inconstant caudate involvement. Myocardial (123)I-meta-iodobenzylguanidine scintigraphy resulted normal. Nigrostriatal denervation was also demonstrated in 2 patients without parkinsonism.

CONCLUSIONS

In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, parkinsonism may be a not rare, late onset manifestation. The clinical picture, the lack of response to dopaminergic treatment, and MRI findings suggest a vascular parkinsonism, which may be preceded by a protracted presymptomatic phase.

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.