Insights From the Histopathologic Analysis of Acquired and Genetic Thoracic Aortic Aneurysms and Dissections.

OBJECTIVE: The purpose of this study was to apply contemporary consensus criteria developed by the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology to the evaluation of aortic pathology, with the expectation that the additional pathologic information may enhance the understanding and management of aortic diseases. METHODS: A scoring system was applied to ascending aortic specimens from 42 patients with heritable thoracic aortic disease and known genetic variations and from 86 patients from a single year, including patients with known genetic variations (n = 12) and patients with sporadic disease (n = 74). RESULTS: The various types of lesions of medial degeneration and the overall severity of medial degeneration overlapped considerably between those patients with heritable disease and those with sporadic disease; however, patients with heritable thoracic aortic disease had significantly more overall medial degeneration (P = .004) and higher levels of elastic fiber fragmentation (P = .03) and mucoid extracellular matrix accumulation (P = .04) than patients with sporadic thoracic aortic disease. Heritable thoracic aortic disease with known genetic variation was more prevalent in women than in men (27.2% vs 9.8%; P = .04), and women had more severe medial degeneration than men (P = .04). Medial degeneration scores were significantly lower for patients with bicuspid aortic valves than for patients with tricuspid aortic valves (P = .03). CONCLUSION: The study's findings indicate considerable overlap in the pattern, extent, and severity of medial degeneration between sporadic and hereditary types of thoracic aortic disease. This finding suggests that histopathologic medial degeneration represents the final common outcome of diverse pathogenetic factors and mechanisms.

Vertebral Tortuosity Is Associated With Increased Rate of Cardiovascular Events in Vascular Ehlers-Danlos Syndrome.

Background Arterial tortuosity is associated with adverse events in Marfan and Loeys-Dietz syndromes but remains understudied in Vascular Ehlers-Danlos syndrome. Methods and Results Subjects with a pathogenic COL3A1 variant diagnosed at age <50 years were included from 2 institutions and the GenTAC Registry (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions). Height-adjusted vertebral artery tortuosity index (VTI-h) using magnetic resonance or computed tomography angiography was calculated. Associations between VTI-h and outcomes of (1) cardiovascular events (arterial dissection/rupture, aneurysm requiring intervention, stroke), or (2) hollow organ collapse/rupture at age <50 years were evaluated using receiver operator curve analysis (using outcome by age 30 years) and mixed-effects Poisson regression for incidence rate ratios. Of 65 subjects (54% male), median VTI-h was 12 (interquartile range, 8-16). Variants were missense in 46%, splice site in 31%, and null/gene deletion in 14%. Thirty-two subjects (49%) had 59 events, including 28 dissections, 5 arterial ruptures, 4 aneurysms requiring intervention, 4 strokes, 11 hollow organ ruptures, and 7 pneumothoraces. Receiver operator curve analysis suggested optimal discrimination at VTI-h ≥15.5 for cardiovascular events (sensitivity 70%, specificity 76%) and no association with noncardiovascular events (area under the curve, 0.49 [95% CI, 0.22-0.78]). By multivariable analysis, older age was associated with increased cardiovascular event rate while VTI-h ≥15.5 was not (incidence rate ratios, 1.79 [95% CI, 0.76-4.24], P=0.185). However, VTI-h ≥15.5 was associated with events among those with high-risk variants <40 years (incidence rate ratios, 4.14 [95% CI, 1.13-15.10], P=0.032), suggesting effect modification by genotype and age. Conclusions Increased arterial tortuosity is associated with a higher incidence rate of cardiovascular events in Vascular Ehlers-Danlos syndrome. Vertebral tortuosity index may be a useful biomarker for prognosis when evaluated in conjunction with genotype and age.

Rare variants in ANO1, encoding a calcium-activated chloride channel, predispose to moyamoya disease.

Moyamoya disease, a cerebrovascular disease leading to strokes in children and young adults, is characterized by progressive occlusion of the distal internal carotid arteries and the formation of collateral vessels. Altered genes play a prominent role in the aetiology of moyamoya disease, but a causative gene is not identified in the majority of cases. Exome sequencing data from 151 individuals from 84 unsolved families were analysed to identify further genes for moyamoya disease, then candidate genes assessed in additional cases (150 probands). Two families had the same rare variant in ANO1, which encodes a calcium-activated chloride channel, anoctamin-1. Haplotype analyses found the families were related, and ANO1 p.Met658Val segregated with moyamoya disease in the family with an LOD score of 3.3. Six additional ANO1 rare variants were identified in moyamoya disease families. The ANO1 rare variants were assessed using patch-clamp recordings, and the majority of variants, including ANO1 p.Met658Val, displayed increased sensitivity to intracellular Ca2+. Patients harbouring these gain-of-function ANO1 variants had classic features of moyamoya disease, but also had aneurysm, stenosis and/or occlusion in the posterior circulation. Our studies support that ANO1 gain-of-function pathogenic variants predispose to moyamoya disease and are associated with unique involvement of the posterior circulation.

An FBN1 deep intronic variant is associated with pseudoexon formation and a variable Marfan phenotype in a five generation family.

Exome sequencing of genes associated with heritable thoracic aortic disease (HTAD) failed to identify a pathogenic variant in a large family with Marfan syndrome (MFS). A genome-wide linkage analysis for thoracic aortic disease identified a peak at 15q21.1, and genome sequencing identified a novel deep intronic FBN1 variant that segregated with thoracic aortic disease in the family (LOD score 2.7) and was predicted to alter splicing. RT-PCR and bulk RNA sequencing of RNA harvested from fibroblasts explanted from the affected proband revealed an insertion of a pseudoexon between exons 13 and 14 of the FBN1 transcript, predicted to lead to nonsense mediated decay (NMD). Treating the fibroblasts with an NMD inhibitor, cycloheximide, greatly improved the detection of the pseudoexon-containing transcript. Family members with the FBN1 variant had later onset aortic events and fewer MFS systemic features than typical for individuals with haploinsufficiency of FBN1. Variable penetrance of the phenotype and negative genetic testing in MFS families should raise the possibility of deep intronic FBN1 variants and the need for additional molecular studies.

Risk Factors for Thoracic Aortic Dissection.

Thoracic aortic aneurysms involving the root and/or the ascending aorta enlarge over time until an acute tear in the intimal layer leads to a highly fatal condition, an acute aortic dissection (AAD). These Stanford type A AADs, in which the tear occurs above the sinotubular junction, leading to the formation of a false lumen in the aortic wall that may extend to the arch and thoracoabdominal aorta. Type B AADs originate in the descending thoracic aorta just distal to the left subclavian artery. Genetic variants and various environmental conditions that disrupt the aortic wall integrity have been identified that increase the risk for thoracic aortic aneurysms and dissections (TAD). In this review, we discuss the predominant TAD-associated risk factors, focusing primarily on the non-genetic factors, and discuss the underlying mechanisms leading to TAD.

Current state and future directions of genomic medicine in aortic dissection: A path to prevention and personalized care.

Aortic dissection confers high mortality and morbidity rates despite advances in treatment, impacts quality of life, and contributes immense burden to the healthcare system globally. Efforts to prevent aortic dissection through screening and management of modifiable risk factors and early detection of aneurysms should incorporate genomic information, as it is integral to stratifying risk. However, effective integration of genomic-guided risk assessment into clinical practice will require addressing implementation barriers that currently permeate our healthcare systems. The Aortic Dissection Collaborative was established to define aortic dissection research priorities through patient engagement. Using a collaborative patient-centered feedback model, our Genomic Medicine Working Group identified related research priorities that could be investigated by pragmatic interventional studies aimed at aortic dissection prevention, utilization of genomic information to improve patient outcomes, and access to genomic medicine services. Further research is also needed to identify the genomic, lifestyle, and environmental risk factors that contribute to aortic dissection so these data can be incorporated into future comparative effectiveness studies to prevent aortic dissection.

Aortic root dilatation and dilated cardiomyopathy in an adult with Tatton-Brown-Rahman syndrome.

Tatton-Brown-Rahman syndrome is an autosomal dominant overgrowth syndrome caused by pathogenic DNMT3A variants in the germline. Clinical findings of tall stature due to postnatal overgrowth, intellectual disability, and characteristic facial features, are the most consistent findings observed in patients with Tatton-Brown-Rahman syndrome (TBRS). Since the syndrome was first described in 2014, an expanding spectrum of neuropsychiatric, musculoskeletal, neurological, and cardiovascular manifestations have been reported. However, most TBRS cases described in the literature are children with de novo DNMT3A variants, signaling a need to better characterize the phenotypes in adults. In this report, we describe a 34 year old referred to genetics for possible Marfan syndrome with aortic root dilatation, mitral valve prolapse, and dilated cardiomyopathy, who was diagnosed with TBRS due to a heterozygous de novo DNMT3A variant. This represents the third reported TBRS case with aortic root dilation and the second with cardiomyopathy. Collectively, these data provide evidence for an association with aortic disease and cardiomyopathy, highlight the clinical overlap with Marfan syndrome, and suggest that cardiovascular surveillance into adulthood is indicated.

In-hospital outcomes and long-term survival of women of childbearing age with aortic dissection.

OBJECTIVE: In the present study, we defined the outcomes and effects of pregnancy in a cohort of women of childbearing age with acute aortic dissection (AAD). METHODS: We reviewed our database of AAD to identify all eligible female patients. Women aged <45 years were included. Data on pregnancy timing with respect to the occurrence of dissection, the demographic data, dissection extent, dissection treatment, dissection-related outcomes, overall maternal and fetal mortality, and genetic testing results were analyzed. RESULTS: A total of 62 women aged <45 years had presented to us with AAD from 1999 to 2017. Of the 62 women, 37 (60%) had had a history of pregnancy at AAD. Of these 37 patients, 10 (27%) had had a peripartum aortic dissection, defined as dissection during pregnancy or within 12 months postpartum. Of the 10 AADs, 5 were type A and 5 were type B. Three patients had presented with AAD during pregnancy (one in the second and two in the third trimester). Five patients (50%) had developed AAD in the immediate postpartum period (within 3 months) and two (20%) in the late postpartum period. For the immediate postpartum AADs (<3 months), four of the five patients delivered via cesarean section. Of these 10 peripartum AADs, 3 (30%) had occurred in patients with known Marfan syndrome. In-hospital mortality for those with peripartum AAD was 10% (1 of 10). Fetal mortality was 20% (2 of 10). CONCLUSIONS: The frequency of aortic dissection in women of childbearing age at our institution was low. However, pregnancy might increase the risk of those young women genetically predisposed to dissection events. From these data, this risk appears to be greatest in the immediate postpartum period, even for those who undergo cesarean section. Close clinical and radiographic surveillance is required for all women with suspected aortopathy, especially in the third trimester and early postpartum period.

Update on the genetic risk for thoracic aortic aneurysms and acute aortic dissections: implications for clinical care.

Genetic variation plays a significant role in predisposing individuals to thoracic aortic aneurysms and dissections. Advances in genomic research have led to the discovery of 11 genes validated to cause heritable thoracic aortic disease (HTAD). Identifying the pathogenic variants responsible for aortic disease in affected patients confers substantial clinical utility by establishing a definitive diagnosis to inform tailored treatment and management, and enables identification of at-risk relatives to prevent downstream morbidity and mortality. The availability and access to clinical genetic testing has improved dramatically such that genetic testing is considered an integral part of the clinical evaluation for patients with thoracic aortic disease. This review provides an update on our current understanding of the genetic basis of thoracic aortic disease, practical recommendations for genetic testing, and clinical implications.

Association of De Novo RNF213 Variants With Childhood Onset Moyamoya Disease and Diffuse Occlusive Vasculopathy.

OBJECTIVE: To test the hypothesis that de novo genetic variants are responsible for moyamoya disease (MMD) in children with unaffected relatives, we performed exome sequencing of 28 affected children and their unaffected parents. METHODS: Exome sequencing was performed on 28 trios of affected patients with MMD and unaffected parents. RESULTS: We identified 3 novel rare de novo RNF213 variants, 1 in the RING domain and 2 in a highly conserved region distal to the RING domain (4,114-4,120). These de novo cases of MMD present at a young age with aggressive MMD and uniquely have additional occlusive vascular lesions, including renal artery stenosis. Two previously reported cases had de novo variants in the same limited region and presented young with aggressive MMD, and 1 case had narrowing of the inferior abdominal aorta. CONCLUSIONS: These results indicate a novel syndrome associated with RNF213 rare variants defined by de novo mutations disrupting highly conserved amino acids in the RING domain and a discrete region distal to the RING domain delimited by amino acids 4,114 to 4,120 leading to onset of severe MMD before 3 years of age and occlusion of other arteries, including the abdominal aorta, renal, iliac, and femoral arteries.

The pleiotropy associated with de novo variants in CHD4, CNOT3, and SETD5 extends to moyamoya angiopathy.

PURPOSE: Moyamoya angiopathy (MMA) is a cerebrovascular disease characterized by occlusion of large arteries, which leads to strokes starting in childhood. Twelve altered genes predispose to MMA but the majority of cases of European descent do not have an identified genetic trigger. METHODS: Exome sequencing from 39 trios were analyzed. RESULTS: We identified four de novo variants in three genes not previously associated with MMA: CHD4, CNOT3, and SETD5. Identification of additional rare variants in these genes in 158 unrelated MMA probands provided further support that rare pathogenic variants in CHD4 and CNOT3 predispose to MMA. Previous studies identified de novo variants in these genes in children with developmental disorders (DD), intellectual disability, and congenital heart disease. CONCLUSION: These genes encode proteins involved in chromatin remodeling, and taken together with previously reported genes leading to MMA-like cerebrovascular occlusive disease (YY1AP1, SMARCAL1), implicate disrupted chromatin remodeling as a molecular pathway predisposing to early onset, large artery occlusive cerebrovascular disease. Furthermore, these data expand the spectrum of phenotypic pleiotropy due to alterations of CHD4, CNOT3, and SETD5 beyond DD to later onset disease in the cerebrovascular arteries and emphasize the need to assess clinical complications into adulthood for genes associated with DD.

Screening for Tay-Sachs disease carriers by full-exon sequencing with novel variant interpretation outperforms enzyme testing in a pan-ethnic cohort.

BACKGROUND: Pathogenic variants in HEXA that impair ß-hexosaminidase A (Hex A) enzyme activity cause Tay-Sachs Disease (TSD), a severe autosomal-recessive neurodegenerative disorder. Hex A enzyme analysis demonstrates near-zero activity in patients affected with TSD and can also identify carriers, whose single functional copy of HEXA results in reduced enzyme activity relative to noncarriers. Although enzyme testing has been optimized and widely used for carrier screening in Ashkenazi Jewish (AJ) individuals, it has unproven sensitivity and specificity in a pan-ethnic population. The ability to detect HEXA variants via DNA analysis has evolved from limited targeting of a few ethnicity-specific variants to next-generation sequencing (NGS) of the entire coding region coupled with interpretation of any discovered novel variants. METHODS: We combined results of enzyme testing, retrospective computational analysis, and variant reclassification to estimate the respective clinical performance of TSD screening via enzyme analysis and NGS. We maximized NGS accuracy by reclassifying variants of uncertain significance and compared to the maximum performance of enzyme analysis estimated by calculating ethnicity-specific frequencies of variants known to yield false-positive or false-negative enzyme results (e.g., pseudodeficiency and B1 alleles). RESULTS: In both AJ and non-AJ populations, the estimated clinical sensitivity, specificity, and positive predictive value were higher by NGS than by enzyme testing. The differences were significant for all comparisons except for AJ clinical sensitivity, where NGS exceeded enzyme testing, but not significantly. CONCLUSIONS: Our results suggest that performance of an NGS-based TSD carrier screen that interrogates the entire coding region and employs novel variant interpretation exceeds that of Hex A enzyme testing, warranting a reconsideration of existing guidelines.

RNF213 rare variants in an ethnically diverse population with Moyamoya disease.

BACKGROUND AND PURPOSE: Moyamoya disease (MMD) is a rare, genetically heterogeneous cerebrovascular disease resulting from occlusion of the distal internal carotid arteries. A variant in the Ring Finger 213 gene (RNF213), altering arginine at position 4810 (p.R4810K), is associated with MMD in Asian populations. However, there are a lack of data on the role of RNF213 in patients with MMD of additional ethnicities and diasporic Asian populations. We investigate the contribution of RNF213 alterations to MMD in an ethnically diverse population based in the United States. METHODS: We initially sequenced RNF213 exons 43, 44, and 45 (encoding the eponymous RING finger domain) and exon 60 (encoding p.R4810K) in 86 ethnically diverse patients with MMD. Comprehensive exome sequencing data from 24 additional patients with MMD was then analyzed to identify RNF213 variants globally. Segregation of variants with MMD and other vascular diseases was assessed in families. RESULTS: RNF213 p.R4810K was identified in 56% (9/16) of patients with MMD of Asian descent and not in 94 patients of non-Asian descent. 3.6% (4/110) of patients had variants in the exons encoding the RING finger domain. Seven additional variants were identified in 29% (7/24) of patients with MMD who underwent exome sequencing. Segregation analysis supported an association with MMD for 2 variants and a lack of association with disease for 1 variant. CONCLUSIONS: These results confirm that alterations in RNF213 predispose patients of diverse ethnicities to MMD, and that the p.R4810K variant predisposes individuals of Asian descent in the United States to MMD.

Molecular diagnosis in vascular Ehlers-Danlos syndrome predicts pattern of arterial involvement and outcomes.

OBJECTIVE: The management of arterial pathology in individuals with vascular Ehlers-Danlos syndrome (vEDS) remains a challenge. Here we describe the correlation between COL3A1 gene mutation type and the clinical phenotype in individuals with vEDS. METHODS: Individuals with confirmed molecular diagnoses of vEDS were enrolled in a multi-institutional natural history study. Data collected included demographics, clinical and family histories, arterial pathology (aneurysm, dissection, and rupture), operative details, and autopsy reports. Individuals were classified into two cohorts by the type of COL3A1 mutations and their effect on the amount of normal collagen produced: those with mutations that lead to minimal (MIN) production (10%-15%) of normal type III collagen and those with haploinsufficiency (HI) mutations that lead to production of 50% of the normal type III collagen. RESULTS: A cohort of 68 individuals (72%) from 56 families had arterial pathology (44% male) with 13% HI. The HI group was older at the time of their first vascular event (mean, 42 [range, 26-58] years vs 33 [range, 8-62] years; P = .016) and had a higher incidence of aortic pathology than the MIN group (56% vs 21%; P = .025). Visceral arterial pathology was seen in 43 arteries in 23 individuals in the MIN group vs only one artery in five individuals in the HI group. Emergency surgical procedures were more likely to be undertaken when vEDS diagnosis was not known (81% vs 41%; P = .005), and 81% of these procedures were open surgical repair compared with 19% endovascular repairs (P = .019). Open and endovascular repairs were equally used in the elective setting. Postoperative complications were highest when the diagnosis of vEDS was not known (62% vs 14%; P < .001) and when procedures were undertaken in an emergency setting (5% vs 55% P < .001). Mortality due to arterial complications was 0% in the HI cohort and 21% in the MIN cohort (P = .132). CONCLUSIONS: Arterial pathology in vEDS individuals is related to the underlying COL3A1 mutation type. The arterial pathology in individuals with HI mutations occurs at later ages with a higher incidence of aortic disease compared with other COL3A1 mutation types. Molecular diagnosis is recommended because diagnosis confirmation, appropriate surveillance, and prophylactic interventions in an elective setting improve surgical outcomes.

Missense mutations in FBN1 exons 41 and 42 cause Weill-Marchesani syndrome with thoracic aortic disease and Marfan syndrome.

Mutations in FBN1 cause a range of overlapping but distinct conditions including Marfan syndrome (MFS), Weill-Marchesani syndrome (WMS), familial thoracic aortic aneurysms/dissections (FTAAD), acromicric dysplasia (AD), and geleophysic dysplasia (GD). Two forms of acromelic dysplasia, AD and GD, characterized by short stature, brachydactyly, reduced joint mobility, and characteristic facies, result from heterozygous missense mutations occurring in exons 41 and 42 of FBN1; missense mutations in these exons have not been reported to cause MFS or other syndromes. Here we report on probands with MFS and WMS who have heterozygous FBN1 missense mutations in exons 41 and 42, respectively. The proband with WMS has ectopia lentis, short stature, thickened pinnae, tight skin, striae atrophicae, reduced extension of the elbows, contractures of the fingers and toes, and brachydactyly and has a missense mutation in exon 42 of FBN1 (c.5242T>C; p.C1748R). He also experienced a previously unreported complication of WMS, an acute thoracic aortic dissection. The second proband displays classic characteristics of MFS, including ectopia lentis, skeletal features, and aortic root dilatation, and has a missense mutation in exon 41 of FBN1 (c.5084G>A; p.C1695Y). These phenotypes provide evidence that missense mutations in exons 41 and 42 of FBN1 lead to MFS and WMS in addition to AD and GD and also suggest that all individuals with pathogenic FBN1 mutations in these exons should be assessed for thoracic aortic disease and ectopia lentis. Further studies are necessary to elucidate the factors responsible for the different phenotypes associated with missense mutations in these exons of FBN1.