Moyamoya-like cerebrovascular disease in a child with a novel mutation in myosin heavy chain 11

Cardiovascular Management of Aortopathy in Children: A Scientific Statement From the American Heart Association

Aortopathy encompasses a spectrum of conditions predisposing to dilation, aneurysm, dissection, or rupture of the aorta and other blood vessels. Aortopathy is diagnosed commonly in children, from infancy through adolescence, primarily affecting the thoracic aorta, with variable involvement of the peripheral vasculature. Pathogeneses include connective tissue disorders, smooth muscle contraction disorders, and congenital heart disease, including bicuspid aortic valve, among others. The American Heart Association has published guidelines for diagnosis and management of thoracic aortic disease. However, these guidelines are predominantly focused on adults and cannot be applied adeptly to growing children with emerging features, growth and developmental changes, including puberty, and different risk profiles compared with adults. Management to reduce risk of progressive aortic dilation and dissection or rupture in children is complex and involves genetic testing, cardiovascular imaging, medical therapy, lifestyle modifications, and surgical guidance that differ in many ways from adult management. Pediatric practice varies widely, likely because aortopathy is pathogenically heterogeneous, including genetic and nongenetic conditions, and there is limited published evidence to guide care in children. To optimize care and reduce variation in management, experts in pediatric aortopathy convened to generate this scientific statement regarding the cardiovascular care of children with aortopathy. Available evidence and expert consensus were combined to create this scientific statement. The most common causes of pediatric aortopathy are reviewed. This document provides a general framework for cardiovascular management of aortopathy in children, while allowing for modification based on the personal and familial characteristics of each child and family.

Endogenous retroviruses are dysregulated in ALS

Amyotrophic lateral sclerosis (ALS) is a universally fatal neurodegenerative disease with no cure. Human endogenous retroviruses (HERVs) have been implicated in its pathogenesis but their relevance to ALS is not fully understood. We examined bulk RNA-seq data from almost 2,000 ALS and unaffected control samples derived from the cortex and spinal cord. Using different methods of feature selection, including differential expression analysis and machine learning, we discovered that transcription of HERV-K loci 1q22 and 8p23.1 were significantly upregulated in the spinal cord of individuals with ALS. Additionally, we identified a subset of ALS patients with upregulated HERV-K expression in the cortex and spinal cord. We also found the expression of HERV-K loci 19q11 and 8p23.1 was correlated with protein coding genes previously implicated in ALS and dysregulated in ALS patients in this study. These results clarify the association of HERV-K and ALS and highlight specific genes in the pathobiology of late-stage ALS.

Cerebral arteriopathies of childhood and stroke - A focus on systemic arteriopathies and pediatric fibromuscular dysplasia (FMD)

Systemic vascular involvement in children with cerebral arteriopathies is increasingly recognized and often highly morbid. Fibromuscular dysplasia (FMD) represents a cerebral arteriopathy with systemic involvement, commonly affecting the renal and carotid arteries. In adults, FMD diagnosis and classification typically relies on angiographic features, like the 'string-of-beads' appearance, following exclusion of other diseases. Pediatric FMD (pFMD) is considered equivalent to adult FMD although robust evidence for similarities is lacking. We conducted a comprehensive literature review on pFMD and revealed inherent differences between pediatric and adult-onset FMD across various domains including epidemiology, natural history, histopathophysiology, clinical, and radiological features. Although focal arterial lesions are often described in children with FMD, the radiological appearance of 'string-of-beads' is highly nonspecific in children. Furthermore, children predominantly exhibit intimal-type fibroplasia, common in other childhood monogenic arteriopathies. Our findings lend support to the notion that pFMD broadly reflects an undefined heterogenous group of monogenic systemic medium-or-large vessel steno-occlusive arteriopathies rather than a single entity. Recognizing the challenges in categorizing complex morphologies of cerebral arteriopathy using current classifications, we propose a novel term for describing children with cerebral and systemic vascular involvement: 'cerebral and systemic arteriopathy of childhood' (CSA-c). This term aims to streamline patient categorization and, when coupled with advanced vascular imaging and high-throughput genomics, will enhance our comprehension of etiology, and accelerate mechanism-targeted therapeutic developments. Lastly, in light of the high morbidity in children with cerebral and systemic arteriopathies, we suggest that investigating for systemic vascular involvement is important in children with cerebral arteriopathies.

Imaging Review of Pediatric Monogenic CNS Vasculopathy with Genetic Correlation

Monogenic cerebral vasculopathy is a rare but progressively recognizable cause of pediatric cerebral vasculopathy manifesting as early as fetal life. These monogenic cerebral vasculopathies can be silent or manifest variably as fetal or neonatal distress, neurologic deficit, developmental delay, cerebral palsy, seizures, or stroke. The radiologic findings can be nonspecific, but the presence of disease-specific cerebral and extracerebral imaging features can point to a diagnosis and guide genetic testing, allowing targeted treatment. The authors review the existing literature describing the frequently encountered and rare monogenic cerebral vascular disorders affecting young patients and describe the relevant pathogenesis, with an attempt to categorize them based on the defective step in vascular homeostasis and/or signaling pathways and characteristic cerebrovascular imaging findings. The authors also highlight the role of imaging and a dedicated imaging protocol in identification of distinct cerebral and extracerebral findings crucial in the diagnostic algorithm and selection of genetic testing. Early and precise recognition of these entities allows timely intervention, preventing or delaying complications and thereby improving quality of life. It is also imperative to identify the specific pathogenic variant and pattern of inheritance for satisfactory genetic counseling and care of at-risk family members. Last, the authors present an image-based approach to these young-onset monogenic cerebral vasculopathies that is guided by the size and predominant radiologic characteristics of the affected vessel with reasonable overlap. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Introducing Exome Sequencing as Part of the Diagnostic Algorithm for Pediatric Nephrology Patients in Bulgaria: A Single-Center Experience

INTRODUCTION

In pediatric kidney patients, where clinical presentation is often not fully developed, and renal biopsy is too risky or inconclusive, it may be difficult to establish the underlying pathology. In cases such as these, genetic diagnosis may be used to guide treatment, prognosis, and counseling. Given the large number of genes involved in kidney disease, introducing next-generation sequencing with extended gene panels as part of the diagnostic algorithm presents a viable solution.

METHODS

A cohort of 87 consecutive independent cases (83 children and 4 terminated pregnancies) with renal disease was recruited. Exome sequencing with MiSeq or NovaSeq 6000 (Illumina) platforms and analysis of extended gene panels were used for genetic testing.

RESULTS

Depending on the presenting pathology, the cases were grouped as patients with glomerular disease, ciliopathies, congenital anomalies, renal electrolyte imbalances, and chronic/acute kidney disease. The overall diagnostic yield was approximately 42% (37 out of 87), with most disease-causing mutations found in COL4A3, COL4A4, COL4A5, and PKHD1 genes. A change or clarification of preliminary diagnosis or adjustment of initial treatment plan based on the results of the genetic testing was made for approximately one-third of the children with meaningful genetic findings (11 out of 37).

DISCUSSION

Our results prove the value of targeted exome sequencing as a non-invasive, versatile, and reliable diagnostic tool for pediatric renal disease patients. Providing genetic diagnosis will help for a better understanding of disease etiology and will give the basis for optimal clinical management and insightful genetic counseling.

Early Onset Parkinson Syndrome, Type A Aortic Aneurysm and Noncompaction Associated With the Novel Variant c.2225C>T in MYH11: A Case Report

Aortic aneurysm, left ventricular noncompaction, and early onset Parkinson syndrome have not been reported in association with MYH11 variants. The patient is a 44-year-old male who developed a progressive ascending aortic aneurysm at age 30, requiring aortic repair at the age of 40. In addition, he developed Parkinson syndrome at the age of 37. He also suffered from myopia, hypothyroidism, arterial hypertension, hyperlipidemia, pre-diabetes, hyperbilirubinemia, obstructive sleep apnea syndrome (OSAS), and muscle cramps. Echocardiography and cardiac MRI showed left ventricular noncompaction. Genetic analysis revealed the novel heterozygous variant c.2225C>T (p.Ala742Val) in MYH11. Family history was positive for arterial hypertension (mother), carcinoma (brother), and diabetes (sister, father). There was consanguinity between the parents. With appropriate treatment, Parkinson syndrome and cardiac anomalies remained stable and there were no complications due to noncompaction or aortic repair. Considering that embryonic vascularisation may be involved in the pathophysiology of noncompaction and that MYH11 is expressed in the myocardium, a causal relationship between the MYH11 variant and noncompaction is conceivable. In conclusion, this is the first case showing an aortic aneurysm associated with noncompaction and Parkinson syndrome in a carrier of the novel, heterozygous variant c.2225C>T in MYH11. Carriers of MYH11 variants should be prospectively and systematically screened for multisystem diseases as soon as the genetic defect is discovered in order not to delay any necessary treatment. First-degree relatives should be screened for the MYH11 variant of a family member to track the trait of inheritance and confirm its pathogenicity.

Genome-wide identification and phenotypic characterization of seizure-associated copy number variations in 741,075 individuals

Copy number variants (CNV) are established risk factors for neurodevelopmental disorders with seizures or epilepsy. With the hypothesis that seizure disorders share genetic risk factors, we pooled CNV data from 10,590 individuals with seizure disorders, 16,109 individuals with clinically validated epilepsy, and 492,324 population controls and identified 25 genome-wide significant loci, 22 of which are novel for seizure disorders, such as deletions at 1p36.33, 1q44, 2p21-p16.3, 3q29, 8p23.3-p23.2, 9p24.3, 10q26.3, 15q11.2, 15q12-q13.1, 16p12.2, 17q21.31, duplications at 2q13, 9q34.3, 16p13.3, 17q12, 19p13.3, 20q13.33, and reciprocal CNVs at 16p11.2, and 22q11.21. Using genetic data from additional 248,751 individuals with 23 neuropsychiatric phenotypes, we explored the pleiotropy of these 25 loci. Finally, in a subset of individuals with epilepsy and detailed clinical data available, we performed phenome-wide association analyses between individual CNVs and clinical annotations categorized through the Human Phenotype Ontology (HPO). For six CNVs, we identified 19 significant associations with specific HPO terms and generated, for all CNVs, phenotype signatures across 17 clinical categories relevant for epileptologists. This is the most comprehensive investigation of CNVs in epilepsy and related seizure disorders, with potential implications for clinical practice.

Association between DIAPH1 variant and posterior circulation involvement with Moyamoya disease

Moyamoya disease (MMD) is a chronic and progressive cerebrovascular stenosis or occlusive disease that occurs near Willis blood vessels. The aim of this study was to investigate the mutation of DIAPH1 in Asian population, and to compare the angiographic features of MMD patients with and without the mutation of the DIAPH1 gene. Blood samples of 50 patients with MMD were collected, and DIAPH1 gene mutation was detected. The angiographic involvement of the posterior cerebral artery was compared between the mutant group and the non-mutant group. The independent risk factors of posterior cerebral artery involvement were determined by multivariate logistic regression analysis. DIAPH1 gene mutation was detected in 9 (18%) of 50 patients, including 7 synonymous mutations and 2 missense mutations. However, the incidence of posterior cerebral artery involvement in mutation positive group was very higher than that in mutation negative group (77.8% versus 12%; p = 0.001). There is an association between DIAPH1 mutation and PCA involvement (odds ratio 29.483, 95% confidence interval 3.920-221.736; p = 0.001). DIAPH1 gene mutation is not a major genetic risk gene for Asian patients with moyamoya disease but may play an important role in the involvement of posterior cerebral artery.

Moyamoya Vasculopathy in Neurofibromatosis Type 1 Pediatric Patients: The Role of Rare Variants of RNF213

Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder caused by mutations in NF1 gene, coding for neurofibromin 1. NF1 can be associated with Moyamoya disease (MMD), and this association, typical of paediatric patients, is referred to as Moyamoya syndrome (MMS). MMD is a cerebral arteriopathy characterized by the occlusion of intracranial arteries and collateral vessel formation, which increase the risk of ischemic and hemorrhagic events. RNF213 gene mutations have been associated with MMD, so we investigated whether rare variants of RNF213 could act as genetic modifiers of MMS phenotype in a pediatric cohort of 20 MMS children, 25 children affected by isolated MMD and 47 affected only by isolated NF1. By next-generation re-sequencing (NGS) of patients' DNA and gene burden tests, we found that RNF213 seems to play a role only for MMD occurrence, while it does not appear to be involved in the increased risk of Moyamoya for MMS patients. We postulated that the loss of neurofibromin 1 can be enough for the excessive proliferation of vascular smooth muscle cells, causing Moyamoya arteriopathy associated with NF1. Further studies will be crucial to support these findings and to elucidate the possible role of other genes, enhancing our knowledge about pathogenesis and treatment of MMS.

Cerebral arteriopathy and ischemic stroke in a pediatric MYH11 patient

OBJECTIVES

Mutations in the MYH11 gene result in smooth muscle cell dysfunction and are associated with familial thoracic aortic aneurysms and dissection. We describe a pediatric patient with a stroke and a pathogenic MYH11 IVS32G>A mutation, and a phenotype similar to ACTA2.

METHODS

A proband girl with an acute ischemic stroke underwent genetic analysis and 7T high-resolution MRI.

RESULTS

A 12-year-old girl presented with a right middle cerebral artery occlusion. She received thrombolysis and underwent mechanical thrombectomy. An extensive stroke work-up was negative. A three-generation pedigree showed a splice site mutation of MYH11 IVS32G>A of the proband and three more family members. A 7T-MRI showed "broomstick-like" straightening of distal arterial segments, a V-shaped anterior corpus callosum and a post-stroke cystic area of encephalomalacia. This vascular appearance and parenchymal abnormalities typically present in patients with an ACTA2 phenotype. 7T-MRI also demonstrated thickening of the right middle cerebral arterial wall.

DISCUSSION

This case suggests that MYH11 patients may have a similar angiographic and brain parenchymal phenotype to patients with ACTA2 mutations. This is the first report of arterial wall thickening in a MYH11 stroke patient using 7T-MRI. Patients with MYH11 mutations may display a focal cerebral steno-occlusive arteriopathy that may lead to stroke.

Influence of Autologous Bone Marrow Stem Cell Therapy on the Levels of Inflammatory Factors and Conexin43 of Patients with Moyamoya Disease

Moyamoya disease is a medical condition that shows the typical characteristics like continuous and chronic thickening of the walls and the contraction of the internal carotid artery; as a result, the internal diameter of the artery gets narrowed. There are six phases of the disease ranging from I to VI (moyamoya vessels completely disappear, followed by the complete blockage of the arteries). Surgery is a commonly recommended treatment for the moyamoya disease. Our research study identifies the effect of autologous bone marrow stem cell therapy (ABMSCT) on the levels of inflammatory factors and Conexin43 (Cx43) protein in patients suffering from moyamoya. In our study, we have selected 52 moyamoya patients admitted to our hospital from 30 July 2019 to 10 February 2020. The control group (CG) was treated with superficial temporal artery to a middle cerebral artery (STA-MCA) bypass + encephalo-duro-myosinangiosis (EDMS). The experimental group (Exp. Grp) was treated with ABMSC. The cerebral vascular tissue of the patients was treated with hematoxylin-eosin (HE) staining. Immunohistochemical staining was used to identify the levels of Cx43 protein. The concentrations of vascular endothelial growth factor (VEGF), inflammatory factor interleukin-6 (IL6), interleukin-1β (IL1β), tumor necrosis factor (TNFα), and anti-inflammatory factor interleukin-1β (IL1β) were determined by enzyme-linked immunosorbent assay (ELISA). We have found that after treatment of the expression of Cx43 protein, the proportions of grade IV (7.7%), grade III (311.5%), and grade II (3.8%) patients in the Exp. Grp were lower than those in the CG. The proportion of grade I patients in the Exp. Grp (77%) was higher than that in the CG (38.5%). After treatment, the inflammatory factors IL6 (0.97 ± 0.82 pg/mL), IL1β (8.33 ± 1.21 pg/mL), and TNFα (1.73 ± 0.71 pg/mL) in the Exp. Grp were lower than those in the CG. The anti-inflammatory factor IL1β (15.09 ± 4.72 pg/mL) increased in the Exp. Grp compared with the CG (11.25 ± 3.48 pg/mL) post treatment. Intracranial infection, hydrocephalus, hemiplegia, and transient neurological dysfunction in the Exp. Grp were lower than those in the CG, with statistical differences (P < 0.05). Our study suggests that the treatment of autologous bone marrow stem cells (ABMSC) was beneficial to balance the inflammatory response of disorders, reduce the damage of vascular tissue in the brain, and regulate tissue repair by co-acting with various inflammatory factors as compared to traditional surgery. We conclude that the involvement of Cx43 in the occurrence and development of moyamoya. We also have found that the risk factors of intracranial infection after ABMSCT were less as compared to those after conventional surgery.

Surgical revascularization for pediatric moyamoya: the role of surgical mentorship in sustaining and developing a neurovascular service

OBJECTIVE

Obtaining operative experience for the treatment of rare conditions in children represents a challenge for pediatric neurosurgeons. Starting in November 2017, a surgeon was mentored in surgical revascularization (SR) for pediatric moyamoya with a view to service development and sustainability. The aim of this audit was to evaluate early outcomes of SR for pediatric moyamoya during and following a surgical mentorship.

METHODS

A retrospective cohort study with chart/database review of consecutive moyamoya surgeries performed by a new attending surgeon (between November 2017 and March 2020) was compared to a previously published cohort from the authors' institution in terms of clinical and angiographic outcomes, complications, operating time, and length of stay. A standardized technique of encephaloduroarteriomyosynangiosis with the superficial temporal artery was used.

RESULTS

Twenty-two children underwent 36 indirect SRs during the study period. Patient demographics were similar between cohorts. The first group of 6 patients had 11 SRs performed jointly by the new attending surgeon mentored by an established senior surgeon (group A), followed by 10 patients with 16 SRs performed independently by the new attending surgeon (group B). The last 6 patients had 9 SRs with the new attending surgeon mentoring a senior fellow (group C) in performing SR. Good angiographic collateralization (Matsushima grades A and B) was observed in 80% of patients, with similar proportions across all 3 groups. A total of 18/19 symptomatic patients (95%) derived symptomatic benefit. There was no perioperative death and, compared to the historical cohort, a similar proportion had a recurrent arterial ischemic event (i.e., acute ischemic stroke) necessitating a second SR (1/22 vs 3/73). Operative times were longest in group C, with no difference in length of hospital stay among the 3 groups.

CONCLUSIONS

Early outcomes demonstrate the feasibility of mentorship for safely incorporating new neurosurgeons in sustaining and developing a tertiary-level surgical service.

Childhood stroke

Stroke is an important cause of neurological morbidity in children; most survivors have permanent neurological deficits that affect the remainder of their life. Stroke in childhood, the focus of this Primer, is distinguished from perinatal stroke, defined as stroke before 29 days of age, because of its unique pathogenesis reflecting the maternal-fetal unit. Although approximately 15% of strokes in adults are haemorrhagic, half of incident strokes in children are haemorrhagic and half are ischaemic. The causes of childhood stroke are distinct from those in adults. Urgent brain imaging is essential to confirm the stroke diagnosis and guide decisions about hyperacute therapies. Secondary stroke prevention strongly depends on the underlying aetiology. While the past decade has seen substantial advances in paediatric stroke research, the quality of evidence for interventions, such as the rapid reperfusion therapies that have revolutionized arterial ischaemic stroke care in adults, remains low. Substantial time delays in diagnosis and treatment continue to challenge best possible care. Effective primary stroke prevention strategies in children with sickle cell disease represent a major success, yet barriers to implementation persist. The multidisciplinary members of the International Pediatric Stroke Organization are coordinating global efforts to tackle these challenges and improve the outcomes in children with cerebrovascular disease.

Western Moyamoya Phenotype: A Scoping Review

Moyamoya, a rare angiographic finding, is characterized by chronic and progressive stenosis at the terminal end of the internal carotid artery, followed by collateralization of the cerebral vasculature at the base of the skull. Coined by Suzuki and Takaku in 1969, the term "moyamoya" means a "puff of smoke" in Japanese, a reference to the angiographic appearance of moyamoya collateralization. Moyamoya is most commonly found in East Asian countries, where much governmental and civilian effort has been expended to characterize this unique disease process. However, despite its rarity, the occurrence of moyamoya in Western countries is associated with significant divergence regarding incidence, gender, sex, age at diagnosis, clinical presentation, and outcomes. Here, we attempted to review the Western literature on moyamoya presentation using the PubMed database to characterize the Western phenotype of moyamoya. We were guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR). We reviewed papers generated from a search with keywords "moyamoya case report," those reported from a Western institution, and those reported on a relevant association. Our scoping review demonstrated various clinical associations with moyamoya. Moreover, we summarized the demographic profile and clinical symptomatology, as well as reported disease associations to better elucidate the Western phenotype of moyamoya.

Cerebral arteriopathy associated with heterozygous variants in the casitas B-lineage lymphoma gene

Objective

To report a series of patients with cerebral arteriopathy associated with heterozygous variants in the casitas B-lineage lymphoma (CBL) gene and examine the functional role of the identified mutant Cbl protein. We hypothesized that mutated Cbl fails to act as a negative regulator of the RAS-mitogen-activated protein kinases (MAPK) signaling pathway, resulting in enhanced vascular fibroblast proliferation and migration and enhanced angiogenesis and collateral vessel formation.

Methods

We performed whole-exome sequencing in 11 separate families referred to Great Ormond Street Hospital, London, with suspected genetic cause for clinical presentation with severe progressive cerebral arteriopathy.

Results

We identified heterozygous variants in the CBL gene in 5 affected cases from 3 families. We show that impaired CBL-mediated degradation of cell surface tyrosine kinase receptors and dysregulated intracellular signaling through the RAS-MAPK pathway contribute to the pathogenesis of the observed arteriopathy. Mutated CBL failed to control the angiogenic signal relay of vascular endothelial growth factor receptor 2, leading to prolonged tyrosine kinase signaling, thus driving angiogenesis and collateral vessel formation. Mutant Cbl promoted myofibroblast migration and proliferation contributing to vascular occlusive disease; these effects were abrogated following treatment with a RAF-RAS-MAPK pathway inhibitor.

Conclusions

We provide a possible mechanism for the arteriopathy associated with heterozygous CBL variants. Identification of the key role for the RAS-MAPK pathway in CBL-mediated cerebral arteriopathy could facilitate identification of novel or repurposed druggable targets for treating these patients and may also provide therapeutic clues for other cerebral arteriopathies.

Intracranial Vessel Stenosis in a Young Patient with an MYH11 Mutation: A Case Report and Review of 2 Prior Cases

BACKGROUND

The MYH11 gene codes for smooth muscle myosin heavy chain, which has a critical function in maintaining vascular wall stability. Patients with this mutation most commonly have aortic and cardiac defects. Documented involvement of intracranial vessels is exceptional.

CASE DESCRIPTION

A 29-year-old woman with a history of patent ductus arteriosus and aortic dissection was found to have incidental bilateral stenosis of the terminal internal carotid arteries as well as the proximal anterior cerebral arteries, middle cerebral arteries, and posterior cerebral arteries on magnetic resonance angiography that was obtained for unrelated symptoms. There was no evidence of basal collateral formation, and a generalized straightening of the vessels was observed. These angiographic findings have been typically observed in patients with ACTA2 mutations. Thus, genetic testing was pursued, which uncovered the presence of an MYH11 mutation. Follow-up imaging at 51 months demonstrated that the intracranial stenosis remained stable without evidence of basal collateral formation. She did not experience any neurologic events during the follow-up interval.

CONCLUSIONS

Intracranial vessel involvement in patients with MYH11 mutations is rare. Vigilant cerebrovascular monitoring should be practiced in this population to guide appropriate management. Reporting of similar cases is important to improve understanding of the development of idiopathic intracranial stenosis in young individuals.

The genetics of aortopathies: Hereditary thoracic aortic aneurysms and dissections

Aortopathies encompass a variety of inherited and acquired pathologies that increase risk of life-threatening dissection or rupture. Identifying individuals with hereditary thoracic aortic aneurysm and dissection (HTAAD) for longitudinal monitoring, medical therapy, or elective and preventative repair is paramount to reduce risk of cardiovascular-related mortality and complications from dissection and rupture. Over the past couple of decades, pathogenic variants in numerous genes have been identified in relation to HTAAD. The genetic diagnosis can help stratify patient risk and provide guidance on medical treatment, timing of prophylactic surgical repair, as well as longitudinal surveillance and imaging. Implicated genes and their associated proteins have been found to act on a diverse variety of pathways, cells and structural components linked to transforming growth factor beta (TGF-β) signaling pathways, disruption of the vascular smooth muscle cell contractile apparatus, and primary disruption of extracellular matrix homeostasis. This review describes relevant genetic variants that may help identify and guide the management of hereditary thoracic aortic aneurysms and dissections.

Development and Validation of a Targeted Next-Generation Sequencing Gene Panel for Children With Neuroinflammation

IMPORTANCE

Neuroinflammatory disorders are a range of severe neurological disorders causing brain and spinal inflammation and are now increasingly recognized in the pediatric population. They are often characterized by marked genotypic and phenotypic heterogeneity, complicating diagnostic work in clinical practice and molecular diagnosis.

OBJECTIVE

To develop and evaluate a next-generation sequencing panel targeting genes causing neuroinflammation or mimicking neuroinflammation.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study in which a total of 257 genes associated with monogenic neuroinflammation and/or cerebral vasculopathy, including monogenic noninflammatory diseases mimicking these entities, were selected. A customized enrichment capture array, the neuroinflammation gene panel (NIP), was created. Targeted high-coverage sequencing was applied to DNA samples taken from eligible patients referred to Great Ormond Street Hospital in London, United Kingdom, between January 1, 2017, and January 30, 2019, because of onset of disease early in life, family history, and/or complex neuroinflammatory phenotypes.

MAIN OUTCOMES AND MEASURES

The main outcome was the percentage of individuals with definitive molecular diagnoses, variant classification, and clinical phenotyping of patients with pathogenic variants identified using the NIP panel. The NIP panel was initially validated in 16 patients with known genetic diagnoses.

RESULTS

The NIP was both sensitive (95%) and specific (100%) for detection of known mutations, including gene deletions, copy number variants, small insertions and deletions, and somatic mosaicism with allele fraction as low as 3%. Prospective testing of 60 patients (30 [50%] male; median [range] age, 9.8 [0.8-20] years) presenting with heterogeneous neuroinflammatory phenotypes revealed at least 1 class 5 (clearly pathogenic) variant in 9 of 60 patients (15%); 18 of 60 patients (30%) had at least 1 class 4 (likely pathogenic) variant. Overall, a definitive molecular diagnosis was established in 12 of 60 patients (20%).

CONCLUSIONS AND RELEVANCE

The NIP was associated with molecular diagnosis in this cohort and complemented routine laboratory and radiological workup of patients with neuroinflammation. Unexpected genotype-phenotype associations in patients with pathogenic variants deviating from the classic phenotype were identified. Obtaining an accurate molecular diagnosis in a timely fashion informed patient management, including successful targeted treatment in some instances and early institution of hematopoietic stem cell transplantation in others.

HDAC9 complex inhibition improves smooth muscle-dependent stenotic vascular disease

Patients with heterozygous missense mutations in the ACTA2 or MYH11 gene are known to exhibit thoracic aortic aneurysm and a risk of early-onset aortic dissection. However, less common phenotypes involving arterial obstruction are also observed, including coronary and cerebrovascular stenotic disease. Herein we implicate the HDAC9 complex in transcriptional silencing of contractile protein-associated genes, known to undergo downregulation in stenotic lesions. Furthermore, neointimal formation was inhibited in HDAC9- or MALAT1-deficient mice with preservation of contractile protein expression. Pharmacologic targeting of the HDAC9 complex through either MALAT1 antisense oligonucleotides or inhibition of the methyltransferase EZH2 (catalytic mediator recruited by the HDAC9 complex) reduced neointimal formation. In conclusion, we report the implication of the HDAC9 complex in stenotic disease and demonstrate that pharmacologic therapy targeting epigenetic complexes can ameliorate arterial obstruction in an experimental system.

Genetics of the extracellular matrix in aortic aneurysmal diseases

Aortic aneurysms are morbid conditions that can lead to rupture or dissection and are categorized as thoracic (TAA) or abdominal aortic aneurysms (AAA) depending on their location. While AAA shares overlapping risk factors with atherosclerotic cardiovascular disease, TAA exhibits strong heritability. Human genetic studies in the past two decades have successfully identified numerous genes involved in both familial and sporadic forms of aortic aneurysm. In this review we will discuss the genetic basis of aortic aneurysm, focusing on the extracellular matrix and how insights from these studies have informed our understanding of human biology and disease pathogenesis.