Baudhuin, Linnea M.

Background: Loeys-Dietz syndrome (LDS) and vascular Ehlers-Danlos syndrome (vEDS) are rare connective tissue disorders characterized by arterial fragility and early-onset vascular events. Stroke risk is elevated in both conditions, but data on stroke subtypes and anticoagulation use remain limited. Understanding the relationship between stroke mechanisms, arrhythmias, and antithrombotic therapy is crucial in these genetically vulnerable populations. Aim: To assess the prevalence and subtypes of stroke in patients with LDS and vEDS. Methods: A retrospective chart review was conducted across three Mayo Clinic sites. Patients with LDS and vEDS were identified using an electronic data extraction tool, followed by manual chart review for diagnostic confirmation. Stroke subtypes, ischemic, dissection-related, and hemorrhagic, were classified based on imaging findings and clinical documentation. Data on atrial arrhythmias, valve replacement status, and anticoagulation use (including warfarin and apixaban) were systematically collected and analyzed. Results: In the LDS cohort, 12 of 94 patients (12.8%) experienced a stroke: 8 ischemic (8.5%), 3 dissection-related (3.2%), and 1 hemorrhagic (1.1%). Atrial fibrillation or flutter was present in 7 patients (58.3%), 6 of whom had ischemic strokes. Among the stroke patients, 9 (75%) had prosthetic valves, 6 mechanical and 3 bioprosthetic, and 4 (33.3%) were on warfarin at the time of the event. In the vEDS cohort, 22 of 132 patients (16.7%) had strokes: 13 ischemic (9.8%) and 9 dissection-related (6.8%). No hemorrhagic strokes were observed. Atrial fibrillation or flutter was documented in 12 patients (54.5%), with 10 experiencing ischemic and 2 dissection-related strokes. Of these, 5 (22.7%) were on apixaban, 3 (13.6%) on warfarin, and 4 (18.2%) were not anticoagulated. None of the vEDS stroke patients had mechanical valves. Conclusion: Ischemic stroke is the most frequent cerebrovascular event in both LDS and vEDS, but dissection-related strokes are more common in vEDS. Atrial arrhythmias often precede ischemic events, yet anticoagulation use varies widely. One-third of dissection-related strokes occurred despite antithrombotic therapy, raising concerns about current management strategies. These findings support the need for syndrome-specific guidelines for stroke prevention, arrhythmia management, and anticoagulation in LDS and vEDS patients.

Thoracic aortic aneurysm and dissection (TAAD) encompasses a clinically heterogeneous group of diseases characterized by high morbidity and mortality. Genetic studies over the past two decades have significantly expanded our understanding of the molecular landscape underlying heritable TAAD, revealing contributions from multiple interconnected biological pathways. This review systematically summarizes more than 75 genes implicated in TAAD pathogenesis, categorizing them according to major mechanistic roles including TGF-β signaling, extracellular matrix remodeling, smooth muscle cell contractility and cytoskeletal regulation, cell–matrix and cell–cell adhesion, metabolic processes, ion transport, and transcriptional regulation. Special emphasis is placed on emerging genes with variable or overlapping clinical phenotypes, dual-mechanism candidates, and their implications for personalized clinical management, including surveillance and surgical intervention thresholds. The integration of molecular insights into clinical practice, along with cautious consideration of genes of uncertain significance, promises to enhance diagnostic precision and risk stratification in individuals and families affected by heritable aortic disease.

Bicuspid aortic valve (BAV) and thoracic aortic aneurysms and dissections (TAAD) are recognized in syndromic connective tissue diseases (CTD), but most cases occur sporadically. The extent to which non-syndromic BAV or TAAD predisposes to additional arteriopathies, particularly in younger individuals, remains unclear. We retrospectively analyzed 1438 patients (mean age = 48.0, 67.7% female), excluding those with CTDs. Participants were ≤60 years old and categorized by the presence of BAV and/or TAAD. We examined co-existing arterial pathologies, including fibromuscular dysplasia, spontaneous coronary artery dissection, abdominal aortic aneurysms (AAA), mesenteric, peripheral extremity, and carotid/cerebral arteriopathies. Overall, 44.6% had either BAV or TAAD, and 27.2% had multiple arteriopathies. While vascular diseases were frequently noted, odds ratios demonstrated no significantly increased risk of extra-aortic arteriopathies in the BAV or TAAD cohorts. AAA exhibited a non-significant trend toward higher prevalence in TAAD patients. These findings support current guidelines recommending targeted imaging (transthoracic echocardiography of the aortic root and ascending aorta) over comprehensive “head-to-pelvis” screening for non-syndromic BAV or TAAD patients without additional risk factors. Ongoing genetic analyses may elucidate whether particular variants predispose to multi-site aneurysms or dissections. Consequently, targeted surveillance remains appropriate, with broader imaging reserved for patients with genetic or clinical indicators of higher risk.

Abstract Objectives Protein-truncating variants in the TTN gene are a well-established cause of dilated cardiomyopathy (DCM). We report a novel case of DCM caused by a mobile element insertion (MEI) in TTN, through which we highlight the key features of MEIs in next-generation sequencing data. Because of the rarity of MEIs, the next-generation sequencing data features associated with these events may be mistaken as noise, potentially leading to missed diagnoses. Methods Next-generation sequencing gene panel testing for DCM was performed on a 17-year-old male patient presenting with severe left ventricular dilatation and systolic dysfunction. Manta was used for structural variant detection, followed by manual review of NGS data for potential structural variants. Results Manta detected a potential insertion in TTN. Manual review identified hallmark features consistent with a LINE-1 MEI. This finding was orthogonally confirmed by long-range polymerase chain reaction and gel electrophoresis, which indicated an insertion of approximately 4 to 5 kilobase pairs. The insertion disrupted the reading frame of TTN within an A-band exon, resulting in protein truncation that was classified as likely pathogenic. Conclusions This case expands the mutational spectrum of TTN protein-truncating variants. It also underscores the importance of recognizing rarer types of pathogenic variants (eg, MEIs) to produce accurate genetic diagnostics.

Abstract Background Despite clinically demonstrated accuracy in next generation sequencing (NGS) data, many clinical laboratories continue to confirm variants with Sanger sequencing, which increases cost of testing and turnaround time. Several studies have assessed the accuracy of NGS in detecting single nucleotide variants; however, less has been reported about insertion, deletion, and deletion-insertion variants (indels). Methods We performed a retrospective analysis from 2015–2022 of indel results from a subset of NGS targeted gene panel tests offered through the Mayo Clinic Genomics Laboratories. We compared results from NGS and Sanger sequencing of indels observed in clinical runs and during the intra-assay validation of the tests. Results Results demonstrated 100% concordance between NGS and Sanger sequencing for over 490 indels (217 unique), ranging in size from 1 to 68 basepairs (bp). The majority of indels were deletions (77%) and 1 to 5 bp in length (90%). Variant frequencies ranged from 11.4% to 67.4% and 85.1% to 100% for heterozygous and homozygous variants, respectively, with a median depth of coverage of 2562×. A subset of indels (7%) were located in complex regions of the genome, and these were accurately detected by NGS. We also demonstrated 100% reproducibility of indel detection (n = 179) during intra-assay validation. Conclusions Together this data demonstrates that reportable indel variants up to 68 bp can be accurately assessed using NGS, even when they occur in complex regions. Depending on the complexity of the region or variant, Sanger sequence confirmation of indels is usually not necessary if the variants meet appropriate coverage and allele frequency thresholds.