Three-generation family with novel contiguous gene deletion on chromosome 2p22 associated with thoracic aortic aneurysm syndrome

Genetic Overlap of Spontaneous Dissection of Either the Thoracic Aorta or the Coronary Arteries

Ascending thoracic aortic dissection (ATAD) is a well-known vascular cause of sudden death. Spontaneous coronary artery dissections (SCAD) are emerging as an important cause of early-onset myocardial infarction and sudden death. Genetic variants in multiple connective tissue genes have been recognized to underlie ATAD; other genetic variants have similarly been recognized to underlie SCAD. Little data are available regarding any genetic commonality between ATAD and SCAD. Our objective is to determine and characterize any genetic overlap between genes coding for ATAD and SCAD. We identified and reviewed 17 retrospective and prospective genetic studies of thoracic aortic dissection and SCAD published between 2016 and 2022 identified through PubMed and Orbis. Articles highlighting the significant plausible triggers for ATAD or SCAD individually were analyzed. No previous study reviewed both ATAD and SCAD genetics together. Separate lists of causative genes were constructed for ATAD and SCAD-and then commonalities were sought. A Venn diagram was constructed to display the genetic overlap and common physiologic pathways involved. We identified a definite, meaningful overlap of 15 independent genes based on a genome-wide association study or other genetic methods. The associated genetic pathways involved various biologic processes including elastin degradation, smooth muscle cell function, and the TGFβ-pathway. The overlapping genes included the following: COL3A1, TGFB2, SMAD3, MYLK, TGFBR2, TGFBR1, LOX, FBN1, NOTCH1, ELN, COL5A1, COL5A2, COL1A2, MYH11, and TLN1. The corresponding molecular pathways were investigated and correlated for both diseases. We are not aware of other studies searching for genetic commonalities between ATAD and SCAD. We have successfully identified overlapping genes-and their corresponding molecular pathways-for ATAD and SCAD. We hope that these insights will lead to further clinical and scientific understanding of each disease through study of their fundamental commonalities.

LTBP1 Gene Expression in the Cerebral Cortex and its Neuroprotective Mechanism in Mice with Postischemic Stroke Epilepsy

OBJECTIVE

This study aimed at exploring the expression level of LTBP1 in the mouse model of epilepsy. The mechanism of LTBP1 in epileptic cerebral neural stem cells was deeply investigated to control the occurrence of epilepsy with neuroprotection.

METHODS

qRT-PCR was conducted for the expression levels of LTBP1 in clinical human epileptic tissues and neural stem cells, as well as normal cerebral tissues and neural stem cells. The mouse model of postischemic stroke epilepsy (PSE) was established by the middle cerebral artery occlusion (MCAO). Then, qRT-PCR was conducted again for the expression levels of LTBP1 in mouse epileptic tissues and neural stem cells as well as normal cerebral tissues and neural stem cells. The activation and inhibitory vectors of LTBP1 were constructed to detect the effects of LTBP1 on the proliferation of cerebral neural stem cells in the PSE model combined with CCK-8. Finally, Western blot was conducted for the specific mechanism of LTBP1 affecting the development of epileptic cells.

RESULTS

Racine score and epilepsy index of 15 mice showed epilepsy symptoms after the determination with MCAO, showing a successful establishment of the PSE model. LTBP1 expression in both diseased epileptic tissues and cells was higher than that in normal clinical epileptic tissues and cells. Meanwhile, qRT-PCR showed higher LTBP1 expression in both mouse epileptic tissues and their neural stem cells compared to that in normal tissues and cells. CCK-8 showed that the activation of LTBP1 stimulated the increased proliferative capacity of epileptic cells, while the inhibition of LTBP1 expression controlled the proliferation of epileptic cells. Western blot showed an elevated expression of TGFβ/SMAD signaling pathway-associated protein SMAD1/5/8 after activating LTBP1. The expression of molecular MMP-13 associated with the occurrence of inflammation was also activated.

CONCLUSION

LTBP1 can affect the changes in inflammation-related pathways by activating the TGFβ/SMAD signaling pathway and stimulate the development of epilepsy, and the inhibition of LTBP1 expression can control the occurrence of epilepsy with neuroprotection.

Tracking an Elusive Killer: State of the Art of Molecular-Genetic Knowledge and Laboratory Role in Diagnosis and Risk Stratification of Thoracic Aortic Aneurysm and Dissection

The main challenge in diagnosing and managing thoracic aortic aneurysm and dissection (TAA/D) is represented by the early detection of a disease that is both deadly and “elusive”, as it generally grows asymptomatically prior to rupture, leading to death in the majority of cases. Gender differences exist in aortic dissection in terms of incidence and treatment options. Efforts have been made to identify biomarkers that may help in early diagnosis and in detecting those patients at a higher risk of developing life-threatening complications. As soon as the hereditability of the TAA/D was demonstrated, several genetic factors were found to be associated with both the syndromic and non-syndromic forms of the disease, and they currently play a role in patient diagnosis/prognosis and management-guidance purposes. Likewise, circulating biomarker could represent a valuable resource in assisting the diagnosis, and several studies have attempted to identify specific molecules that may help with risk stratification outside the emergency department. Even if promising, those data lack specificity/sensitivity, and, in most cases, they need more testing before entering the “clinical arena”. This review summarizes the state of the art of the laboratory in TAA/D diagnostics, with particular reference to the current and future role of molecular-genetic testing.

Latent TGFβ binding proteins 1 and 3 protect the larval zebrafish outflow tract from aneurysmal dilatation

Aortic root aneurysm is a common cause of morbidity and mortality in Loeys-Dietz and Marfan Syndromes, where perturbations in TGFβ signaling play a causal or contributory role, respectively. Despite the advantages of cross-species disease modeling, animal models of aortic root aneurysm are largely restricted to genetically engineered mice. Here, we report that zebrafish devoid of latent TGFβ binding protein (ltbp) 1 and 3 develop rapid and severe aneurysm of the outflow tract (OFT), the aortic root equivalent. Similar to syndromic aneurysm tissue, the distended OFTs display evidence for paradoxical hyperactivated TGFβ signaling. RNA-sequencing revealed significant overlap between the molecular signatures of disease tissue from mutant zebrafish and Marfan mice. Lastly, chemical inhibition of TGFβ signaling in wild-type animals phenocopied mutants but chemical activation did not, demonstrating that TGFβ signaling is protective against aneurysm. Human relevance is supported by recent studies implicating genetic lesions in LTBP3 and potentially LTBP1 as heritable causes of aortic root aneurysm. Ultimately, our data demonstrate that zebrafish can now be leveraged to interrogate thoracic aneurysmal disease and identify novel lead compounds through small molecule suppressor screens.

Precision Medicine Approaches to Vascular Disease: JACC Focus Seminar 2/5

In this second of a 5-part Focus Seminar series, we focus on precision medicine in the context of vascular disease. The most common vascular disease worldwide is atherosclerosis, which is the primary cause of coronary artery disease, peripheral vascular disease, and a large proportion of strokes and other disorders. Atherosclerosis is a complex genetic disease that likely involves many hundreds to thousands of single nucleotide polymorphisms, each with a relatively modest effect for causing disease. Conversely, although less prevalent, there are many vascular disorders that typically involve only a single genetic change, but these changes can often have a profound effect that is sufficient to cause disease. These are termed "Mendelian vascular diseases," which include Marfan and Loeys-Dietz syndromes. Given the very different genetic basis of atherosclerosis versus Mendelian vascular diseases, this article was divided into 2 parts to cover the most promising precision medicine approaches for these disease types.

The Molecular Genetics of Marfan Syndrome

Marfan syndrome (MFS) is a complex connective tissue disease that is primarily characterized by cardiovascular, ocular and skeletal systems disorders. Despite its rarity, MFS severely impacts the quality of life of the patients. It has been shown that molecular genetic factors serve critical roles in the pathogenesis of MFS. FBN1 is associated with MFS and the other genes such as FBN2, transforming growth factor beta (TGF-β) receptors (TGFBR1 and TGFBR2), latent TGF-β-binding protein 2 (LTBP2) and SKI, amongst others also have their associated syndromes, however high overlap may exist between these syndromes and MFS. Abnormalities in the TGF-β signaling pathway also contribute to the development of aneurysms in patients with MFS, although the detailed molecular mechanism remains unclear. Mutant FBN1 protein may cause unstableness in elastic structures, thereby perturbing the TGF-β signaling pathway, which regulates several processes in cells. Additionally, DNA methylation of FBN1 and histone acetylation in an MFS mouse model demonstrated that epigenetic factors play a regulatory role in MFS. The purpose of the present review is to provide an up-to-date understanding of MFS-related genes and relevant assessment technologies, with the aim of laying a foundation for the early diagnosis, consultation and treatment of MFS.

Thoracic aortic aneurysm gene dictionary

Thoracic aortic aneurysm is typically clinically silent, with a natural history of progressive enlargement until a potentially lethal complication such as rupture or dissection occurs. Underlying genetic predisposition strongly influences the risk of thoracic aortic aneurysm and dissection. Familial cases are more virulent, have a higher rate of aneurysm growth, and occur earlier in life. To date, over 30 genes have been associated with syndromic and non-syndromic thoracic aortic aneurysm and dissection. The causative genes and their specific variants help to predict the disease phenotype, including age at presentation, risk of dissection at small aortic sizes, and risk of other cardiovascular and systemic manifestations. This genetic "dictionary" is already a clinical reality, allowing us to personalize care based on specific causative mutations for a substantial proportion of these patients. Widespread genetic sequencing of thoracic aortic aneurysm and dissection patients has been and continues to be crucial to the rapid expansion of this dictionary and ultimately, the delivery of truly personalized care to every patient.

Case report: early aortic valve degeneration associated with interstitial deletion of chromosome 2-46,XX,del (2)(q31.3; q32.2)

Background

Interstitial deletions within the long arm of chromosome 2, involving the 2q31q33 region, are rare but are known to be associated with delays in development, behavioral problems, facial dysmorphism and various hand/foot anomalies.

Case presentation

Here, we describe a case with an interstitial 2q31.3.q32.2 deletion, presenting the previously described phenotype, exhibiting fibromyxoid degeneration of the aortic valve in addition to previously described clinical features.

Conclusion

Interstitial deletion in chromosome 2q31.2q32.3 might be associated to a fibromyxoid degeneration of valvular leaflets generating regurgitation. Patients diagnosed with this mutation may require investigation to rule out a valvular disease.

De novo EIF2AK1 and EIF2AK2 Variants Are Associated with Developmental Delay, Leukoencephalopathy, and Neurologic Decompensation

EIF2AK1 and EIF2AK2 encode members of the eukaryotic translation initiation factor 2 alpha kinase (EIF2AK) family that inhibits protein synthesis in response to physiologic stress conditions. EIF2AK2 is also involved in innate immune response and the regulation of signal transduction, apoptosis, cell proliferation, and differentiation. Despite these findings, human disorders associated with deleterious variants in EIF2AK1 and EIF2AK2 have not been reported. Here, we describe the identification of nine unrelated individuals with heterozygous de novo missense variants in EIF2AK1 (1/9) or EIF2AK2 (8/9). Features seen in these nine individuals include white matter alterations (9/9), developmental delay (9/9), impaired language (9/9), cognitive impairment (8/9), ataxia (6/9), dysarthria in probands with verbal ability (6/9), hypotonia (7/9), hypertonia (6/9), and involuntary movements (3/9). Individuals with EIF2AK2 variants also exhibit neurological regression in the setting of febrile illness or infection. We use mammalian cell lines and proband-derived fibroblasts to further confirm the pathogenicity of variants in these genes and found reduced kinase activity. EIF2AKs phosphorylate eukaryotic translation initiation factor 2 subunit 1 (EIF2S1, also known as EIF2α), which then inhibits EIF2B activity. Deleterious variants in genes encoding EIF2B proteins cause childhood ataxia with central nervous system hypomyelination/vanishing white matter (CACH/VWM), a leukodystrophy characterized by neurologic regression in the setting of febrile illness and other stressors. Our findings indicate that EIF2AK2 missense variants cause a neurodevelopmental syndrome that may share phenotypic and pathogenic mechanisms with CACH/VWM.

Tumour suppressor candidate 3 inhibits biological function and increases endoplasmic reticulum stress of melanoma cells WM451 by regulating AKT/GSK3-β/β-catenin pathway

Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. This study aims to evaluate the significance of TUSC3, an endoplasmic reticulum stress (ERS)-inducible gene and explore its relationship with AKT/GSK3-β/β-catenin signalling pathway in melanoma cell WM451. We investigated TUSC3 expression in melanoma cell by qRT-PCR, CCK-8 and clonal formation assays were utilized to evaluate cell proliferation. Wound healing and transwell experiments detected cell migration and invasion. Flow cytometry detected the level of apoptosis. Western blot analysed MMP2, MMP9, p-AKT, p-GSK3-β, β-catenin and AKT, GSK3-β, ERS-related proteins and apoptosis-related proteins in WM451 cells. The results revealed that TUSC3 was remarkably decreased in melanoma cell lines. Overexpression of TUSC3 significantly inhibits melanoma cell WM451 biological functions and promotes expression of ERS-related proteins in WM451 cells, increases ERS in WM451 cells by inhibiting AKT/GSK3-β/β-catenin pathway. These finding suggest that TUSC3 regulates biological functions of melanoma cells WM451 and increases ERS in melanoma cells WM451 via the inhibition of the AKT/GSK3-β/β-catenin signalling pathway. SIGNIFICANCE OF THE STUDY: Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. Therefore, studying the molecular mechanism of melanoma occurrence and metastasis is essential for the treatment of melanoma. Meanwhile, mounting studies suggest that TUSC3 is considered to be closely associated with the development of various malignancies. TUSC3 regulates proliferation, migration and epithelial-to-mesenchymal transition, but the molecular mechanism of the tumour suppressor effects of TUSC3 on melanoma cells is not well understood. Our study demonstrates that TUSC3 inhibits biological function of melanoma cells and increases ERS in melanoma cells by inhibiting AKT/GSK3-β/β-catenin pathway. And this is expected to be a new target and method for the treatment of melanoma.

The Genetics of Thoracic Aortic Aneurysms and Dissection: A Clinical Perspective

Thoracic aortic aneurysm and dissection (TAAD) affects many patients globally and has high mortality rates if undetected. Once thought to be solely a degenerative disease that afflicted the aorta due to high pressure and biomechanical stress, extensive investigation of the heritability and natural history of TAAD has shown a clear genetic basis for the disease. Here, we review both the cellular mechanisms and clinical manifestations of syndromic and non-syndromic TAAD. We particularly focus on genes that have been linked to dissection at diameters <5.0 cm, the current lower bound for surgical intervention. Genetic screening tests to identify patients with TAAD associated mutations that place them at high risk for dissection are also discussed.

Genes Associated with Thoracic Aortic Aneurysm and Dissection: 2019 Update and Clinical Implications

Thoracic aortic aneurysm is a typically silent disease characterized by a lethal natural history. Since the discovery of the familial nature of thoracic aortic aneurysm and dissection (TAAD) almost 2 decades ago, our understanding of the genetics of this disorder has undergone a transformative amplification. To date, at least 37 TAAD-causing genes have been identified and an estimated 30% of the patients with familial nonsyndromic TAAD harbor a pathogenic mutation in one of these genes. In this review, we present our yearly update summarizing the genes associated with TAAD and the ensuing clinical implications for surgical intervention. Molecular genetics will continue to bolster this burgeoning catalog of culprit genes, enabling the provision of personalized aortic care.

LTBP2-related "Marfan-like" phenotype in two Roma/Gypsy subjects with the LTBP2 homozygous p.R299X variant

Recessive variants in LTBP2 are associated with eye-restricted phenotypes including (a) primary congenital glaucoma and (b) microspherophakia/megalocornea and ectopia lentis with/without secondary glaucoma. Nosology of LTBP2 pathology in humans is apparently in contrast with the consolidated evidence of a wide expression of this gene in the developing embryo. Accordingly, in previously published patients with LTBP2-related eye disease, additional extraocular findings have been occasionally reported and include, among others, high-arched palate, tall stature, and variable cardiac involvement. Anyway, no emphasis was put on such systemic manifestations. Here, we report two unrelated Roma/Gypsy patients first ascertained for a multisystem disorder mainly characterized by primary congenital glaucoma, complex congenital heart defect, tall stature, long fingers, skin striae and dystrophic scarring, and resembling Marfan syndrome. Heart involvement was severe with polyvalvular heart dysplasia in one, and transposition of great arteries, thoracic arterial tortuosity, polyvalvular heart dysplasia, and neo-aortic root dilatation in the other. Both patients were homozygous for the recurrent c.895C>T[p.(R299X)] variant, typically found in individuals of Roma/Gypsy descent with an eye-restricted phenotype. Our findings point out LTBP2 as responsible of a systemic phenotype coherent with the community of syndromes related to anomalies in genes involved in the TGFβ-pathway. Among these disorders, LTBP2-related systemic disease emerges as a distinct condition with expanding prognostic implications and autosomal recessive inheritance.