Publications by authors named "Dong-chuan Guo"

56 Publications

Regulatory variants in TCF7L2 are associated with thoracic aortic aneurysm.

Am J Hum Genet 2021 09 14;108(9):1578-1589. Epub 2021 Jul 14.

K.G. Jebsen Center for Genetic Epidemiology, Department of Public Health and Nursing, NTNU, Norwegian University of Science and Technology, Trondheim 7030, Norway.

Thoracic aortic aneurysm (TAA) is characterized by dilation of the aortic root or ascending/descending aorta. TAA is a heritable disease that can be potentially life threatening. While 10%-20% of TAA cases are caused by rare, pathogenic variants in single genes, the origin of the majority of TAA cases remains unknown. A previous study implicated common variants in FBN1 with TAA disease risk. Here, we report a genome-wide scan of 1,351 TAA-affected individuals and 18,295 control individuals from the Cardiovascular Health Improvement Project and Michigan Genomics Initiative at the University of Michigan. We identified a genome-wide significant association with TAA for variants within the third intron of TCF7L2 following replication with meta-analysis of four additional independent cohorts. Common variants in this locus are the strongest known genetic risk factor for type 2 diabetes. Although evidence indicates the presence of different causal variants for TAA and type 2 diabetes at this locus, we observed an opposite direction of effect. The genetic association for TAA colocalizes with an aortic eQTL of TCF7L2, suggesting a functional relationship. These analyses predict an association of higher expression of TCF7L2 with TAA disease risk. In vitro, we show that upregulation of TCF7L2 is associated with BCL2 repression promoting vascular smooth muscle cell apoptosis, a key driver of TAA disease.
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http://dx.doi.org/10.1016/j.ajhg.2021.06.016DOI Listing
September 2021

Pathogenic variants in THSD4, encoding the ADAMTS-like 6 protein, predispose to inherited thoracic aortic aneurysm.

Genet Med 2021 01 28;23(1):111-122. Epub 2020 Aug 28.

Laboratory for Vascular Translational Science, INSERM U1148, Université de Paris, Centre Hospitalo-Universitaire Xavier Bichat, APHP, Paris, France.

Purpose: Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease with often unrecognized inherited forms. We sought to identify novel pathogenic variants associated with autosomal dominant inheritance of TAAD.

Methods: We analyzed exome sequencing data from 35 French TAAD families and performed next-generation sequencing capture panel of genes in 1114 unrelated TAAD patients. Functional effects of pathogenic variants identified were validated in cell, tissue, and mouse models.

Results: We identified five functional variants in THSD4 of which two heterozygous variants lead to a premature termination codon. THSD4 encodes ADAMTSL6 (member of the ADAMTS/L superfamily), a microfibril-associated protein that promotes fibrillin-1 matrix assembly. The THSD4 variants studied lead to haploinsufficiency or impaired assembly of fibrillin-1 microfibrils. Thsd4 mice showed progressive dilation of the thoracic aorta. Histologic examination of aortic samples from a patient carrying a THSD4 variant and from Thsd4 mice, revealed typical medial degeneration and diffuse disruption of extracellular matrix.

Conclusion: These findings highlight the role of ADAMTSL6 in aortic physiology and TAAD pathogenesis. They will improve TAAD management and help develop new targeted therapies.
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http://dx.doi.org/10.1038/s41436-020-00947-4DOI Listing
January 2021

Do Variants Predispose to Thoracic Aortic Aneurysms and Dissections?

Circ Genom Precis Med 2019 12 15;12(12):e002626. Epub 2019 Nov 15.

Division of Medical Genetics, Department of Internal Medicine, The University of Texas Health Science Center (H.L.H., E.S.R., D.-c.G., L.X., D.M.M.).

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http://dx.doi.org/10.1161/CIRCGEN.119.002626DOI Listing
December 2019

Grange syndrome due to homozygous YY1AP1 missense rare variants.

Am J Med Genet A 2019 12 21;179(12):2500-2505. Epub 2019 Oct 21.

Division of Medical Genetics, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houstan, Texas.

Grange syndrome (OMIM 602531) is an autosomal recessive condition characterized by severe early onset vascular occlusive disease and variable penetrance of brachydactyly, syndactyly, bone fragility, and learning disabilities. Grange syndrome is caused by homozygous or compound heterozygous loss-of-function variants in the YYA1P1 gene. We report on the case of a 53-year old female with novel homozygous missense variants in YYA1P1 (c.1079C>T, p.Pro360Leu), presenting with a history of brachysyndactyly, hypertension, and ischemic stroke. Imaging studies revealed stenosis of the bilateral internal carotid with extensive collateralization of cerebral vessels in a moyamoya-like pattern, along with stenosis in the splenic, common hepatic, celiac, left renal, and superior mesenteric arteries. Functional studies conducted with the patient's dermal fibroblasts suggest that the p.Pro360Leu variant decreases the stability of the YY1AP1 protein. This is the first report of a missense variant associated with Grange syndrome characterized by later onset of vascular disease and a lack of developmental delay and bone fragility.
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http://dx.doi.org/10.1002/ajmg.a.61379DOI Listing
December 2019

The natural history of type B aortic dissection in patients with PRKG1 mutation c.530G>A (p.Arg177Gln).

J Vasc Surg 2019 09 11;70(3):718-723. Epub 2019 Mar 11.

Division of Medical Genetics, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Tex.

Objective: The c.530G>A (p.Arg177Gln) mutation in PRKG1 has been shown to be associated with thoracic aortic aneurysms and dissections. This rare mutation accounts for an estimated 1% of nonsyndromic heritable thoracic aortic disease. We sought to describe the clinical presentation of type B aortic dissection (TBAD), management, and outcomes in patients with this mutation.

Methods: This is a descriptive multi-institutional retrospective study of patients from six families with the PRKG1 mutation. Patients with TBAD were selected for analysis. Demographics, family histories, TBAD management, and outcomes were reviewed.

Results: Of the 29 individuals diagnosed with the PRKG1 mutation, 12 (41.3%) had TBAD (50% male, TBAD median age: 31 years [range, 16-58 years], median follow-up: 6 years [range, 3-15 years] after TBAD). All had a family history of aortic dissections and none had features of Marfan syndrome. The median size of the descending thoracic aorta (DTA) at TBAD was 4.1 cm (range, 3.8-5 cm). Most cases (9 acute TBAD, 1 incidental TBAD diagnosis during screening) were managed medically. One case had open DTA repair the acute phase. Repair for dissection-related aneurysmal degeneration was performed in seven cases (58.3%) in the chronic phase at a median of 2 years (range, 1-8 years) after TBAD. In four cases (33.3%), the DTA remained stable in size over a range of 1 to 7 years after TBAD. Type A aortic dissection subsequent to TBAD occurred in three cases (25%). There were four (33.3%) deaths in the series, all aortic related at a median age of 24 years (range, 19-43 years).

Conclusions: The PRKG1 (p.Arg177Gln) mutation although rare is associated with nonsyndromic TBAD in young and middle-aged patients. Workup for this gene mutation should be included as part of the workup for TBAD etiology in relatively young patients and those with familial history of aortic dissections. Once diagnosed, testing of first-degree family members is warranted. In all individuals with a PRKG1 mutation, close follow-up for aortic root dilatation and hypertension control is essential to reduce the risk of type A or type B aortic dissection, and in cases of TBAD, to decrease the risk of dissection-related aneurysmal degeneration.
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http://dx.doi.org/10.1016/j.jvs.2018.12.032DOI Listing
September 2019

SMAD4 rare variants in individuals and families with thoracic aortic aneurysms and dissections.

Eur J Hum Genet 2019 07 26;27(7):1054-1060. Epub 2019 Feb 26.

Department of Internal Medicine, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, USA.

SMAD4 pathogenic variants cause juvenile polyposis (JPS) and hereditary hemorrhagic telangiectasia (HHT), and 40% of affected individuals also have thoracic aortic disease. At the same time, SMAD4 pathogenic variants have not been reported in thoracic aortic disease families without JPS-HHT. A SMAD4 heterozygous variant, c.290G>T, p.(Arg97Leu), not present in population databases and predicted to be damaging to protein function, was identified in a family with thoracic aortic disease and no evidence of HHT or JPS. Cellular studies revealed that the SMAD4 p.(Arg97Leu) alteration increased SMAD4 ubiquitination and 26S proteasome-mediated protein degradation. Smooth muscle cells (SMCs) infected with lentivirus expressing the SMAD4 p.(Arg97Leu) variant demonstrated reduced contractile protein gene expression when compared to that of wild-type SMAD4. In addition, two rare variants were identified in individuals with early age of onset of thoracic aortic dissection. These results suggest that SMAD4 rare missense variants can lead to thoracic aortic disease in individuals who do not have JPS or HHT.
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http://dx.doi.org/10.1038/s41431-019-0357-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777456PMC
July 2019

pathogenic variants: risk for thoracic aortic disease and associated complications from the Montalcino Aortic Consortium.

J Med Genet 2019 04 19;56(4):252-260. Epub 2019 Jan 19.

Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, USA.

Background: Pathogenic variants in cause thoracic aortic aneurysms and dissections, along with aneurysms and rupture of other arteries. Here, we examined differences in clinical presentation of aortic events (dissection or surgical repair of an aneurysm) with respect to age and variant type in an international cohort of individuals with variants.

Methods: Aortic status and events, vital status and clinical features were abstracted through retrospective review of medical records of 212 individuals with 51 unique variants, including haploinsufficiency (HI) and missense substitutions in the MH2 domain, as well as novel in-frame deletions and missense variants in the MH1 domain.

Results: Aortic events were documented in 37% of cases, with dissections accounting for 70% of events. The median age at first aortic event was significantly lower in individuals with MH2 missense variants than those with HI variants (42years vs 49 years; p=0.003), but there was no difference in frequency of aortic events by variant type. The cumulative risk of an aortic event was 50% at 54 years of age. No aortic events in childhood were observed.

Conclusions: pathogenic variants cause thoracic aortic aneurysms and dissections in the majority of individuals with variable age of onset and reduced penetrance. Of the covariates examined, the type of underlying variant was responsible for some of this variation. Later onset of aortic events and the absence of aortic events in children associated with variants support gene-specific management of this disorder.
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http://dx.doi.org/10.1136/jmedgenet-2018-105583DOI Listing
April 2019

MYLK pathogenic variants aortic disease presentation, pregnancy risk, and characterization of pathogenic missense variants.

Genet Med 2019 01 20;21(1):144-151. Epub 2018 Jun 20.

Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA.

Purpose: Heritable thoracic aortic disease can result from null variants in MYLK, which encodes myosin light-chain kinase (MLCK). Data on which MYLK missense variants are pathogenic and information to guide aortic disease management are limited.

Methods: Clinical data from 60 cases with MYLK pathogenic variants were analyzed (five null and two missense variants), and the effect of missense variants on kinase activity was assessed.

Results: Twenty-three individuals (39%) experienced an aortic event (defined as aneurysm repair or dissection); the majority of these events (87%) were aortic dissections. Aortic diameters were minimally enlarged at the time of dissection in many cases. Time-to-aortic-event curves showed that missense pathogenic variant (PV) carriers have earlier-onset aortic events than null PV carriers. An MYLK missense variant segregated with aortic disease over five generations but decreases MYLK kinase acitivity marginally. Functional Assays fail to identify all pathogenic variants in MYLK.

Conclusion: These data further define the aortic phenotype associated with MYLK pathogenic variants. Given minimal aortic enlargement before dissection, an alternative approach to guide the timing of aortic repair is proposed based on the probability of a dissection at a given age.
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http://dx.doi.org/10.1038/s41436-018-0038-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6400320PMC
January 2019

Ari-1 Regulates Myonuclear Organization Together with Parkin and Is Associated with Aortic Aneurysms.

Dev Cell 2018 04;45(2):226-244.e8

Program in Developmental Biology, Baylor College of Medicine (BCM), Houston, TX 77030, USA; Department of Molecular and Human Genetics, BCM, Houston, TX 77030, USA; Howard Hughes Medical Institute, BCM, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital (TCH), Houston, TX 77030, USA; Department of Neuroscience, BCM, Houston, TX 77030, USA. Electronic address:

Nuclei are actively positioned and anchored to the cytoskeleton via the LINC (Linker of Nucleoskeleton and Cytoskeleton) complex. We identified mutations in the Parkin-like E3 ubiquitin ligase Ariadne-1 (Ari-1) that affect the localization and distribution of LINC complex members in Drosophila. ari-1 mutants exhibit nuclear clustering and morphology defects in larval muscles. We show that Ari-1 mono-ubiquitinates the core LINC complex member Koi. Surprisingly, we discovered functional redundancy between Parkin and Ari-1: increasing Parkin expression rescues ari-1 mutant phenotypes and vice versa. We further show that rare variants in the human homolog of ari-1 (ARIH1) are associated with thoracic aortic aneurysms and dissections, conditions resulting from smooth muscle cell (SMC) dysfunction. Human ARIH1 rescues fly ari-1 mutant phenotypes, whereas human variants found in patients fail to do so. In addition, SMCs obtained from patients display aberrant nuclear morphology. Hence, ARIH1 is critical in anchoring myonuclei to the cytoskeleton.
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http://dx.doi.org/10.1016/j.devcel.2018.03.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920516PMC
April 2018

LTBP3 Pathogenic Variants Predispose Individuals to Thoracic Aortic Aneurysms and Dissections.

Am J Hum Genet 2018 04;102(4):706-712

Department of Internal Medicine, University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA. Electronic address:

The major diseases affecting the thoracic aorta are aneurysms and acute dissections, and pathogenic variants in 11 genes are confirmed to lead to heritable thoracic aortic disease. However, many families in which multiple members have thoracic aortic disease do not have alterations in the known aortopathy genes. Genes highly expressed in the aorta were assessed for rare variants in exome sequencing data from such families, and compound rare heterozygous variants (p.Pro45Argfs25 and p.Glu750) in LTBP3 were identified in affected members of one family. A homozygous variant (p.Asn678_Gly681delinsThrCys) that introduces an additional cysteine into an epidermal growth factor (EGF)-like domain in the corresponding protein, latent TGF-β binding protein (LTBP-3), was identified in a second family. Individuals with compound heterozygous or homozygous variants in these families have aneurysms and dissections of the thoracic aorta, as well as aneurysms of the abdominal aorta and other arteries, along with dental abnormalities and short stature. Heterozygous carriers of the p.Asn678_Gly681delinsThrCys variant have later onset of thoracic aortic disease, as well as dental abnormalities. In these families, LTBP3 variants segregated with thoracic aortic disease with a combined LOD score of 3.9. Additionally, heterozygous rare LTBP3 variants were found in individuals with early onset of acute aortic dissections, and some of these variants disrupted LTBP-3 levels or EGF-like domains. When compared to wild-type mice, Ltbp3 mice have enlarged aortic roots and ascending aortas. In summary, homozygous LTBP3 pathogenic variants predispose individuals to thoracic aortic aneurysms and dissections, along with the previously described skeletal and dental abnormalities.
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http://dx.doi.org/10.1016/j.ajhg.2018.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985335PMC
April 2018

Protein-altering and regulatory genetic variants near GATA4 implicated in bicuspid aortic valve.

Nat Commun 2017 05 25;8:15481. Epub 2017 May 25.

Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA.

Bicuspid aortic valve (BAV) is a heritable congenital heart defect and an important risk factor for valvulopathy and aortopathy. Here we report a genome-wide association scan of 466 BAV cases and 4,660 age, sex and ethnicity-matched controls with replication in up to 1,326 cases and 8,103 controls. We identify association with a noncoding variant 151 kb from the gene encoding the cardiac-specific transcription factor, GATA4, and near-significance for p.Ser377Gly in GATA4. GATA4 was interrupted by CRISPR-Cas9 in induced pluripotent stem cells from healthy donors. The disruption of GATA4 significantly impaired the transition from endothelial cells into mesenchymal cells, a critical step in heart valve development.
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http://dx.doi.org/10.1038/ncomms15481DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5458508PMC
May 2017

Loss-of-Function Mutations in YY1AP1 Lead to Grange Syndrome and a Fibromuscular Dysplasia-Like Vascular Disease.

Am J Hum Genet 2017 Jan 8;100(1):21-30. Epub 2016 Dec 8.

Department of Internal Medicine, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA. Electronic address:

Fibromuscular dysplasia (FMD) is a heterogeneous group of non-atherosclerotic and non-inflammatory arterial diseases that primarily involves the renal and cerebrovascular arteries. Grange syndrome is an autosomal-recessive condition characterized by severe and early-onset vascular disease similar to FMD and variable penetrance of brachydactyly, syndactyly, bone fragility, and learning disabilities. Exome-sequencing analysis of DNA from three affected siblings with Grange syndrome identified compound heterozygous nonsense variants in YY1AP1, and homozygous nonsense or frameshift YY1AP1 variants were subsequently identified in additional unrelated probands with Grange syndrome. YY1AP1 encodes yin yang 1 (YY1)-associated protein 1 and is an activator of the YY1 transcription factor. We determined that YY1AP1 localizes to the nucleus and is a component of the INO80 chromatin remodeling complex, which is responsible for transcriptional regulation, DNA repair, and replication. Molecular studies revealed that loss of YY1AP1 in vascular smooth muscle cells leads to cell cycle arrest with decreased proliferation and increased levels of the cell cycle regulator p21/WAF/CDKN1A and disrupts TGF-β-driven differentiation of smooth muscle cells. Identification of YY1AP1 mutations as a cause of FMD indicates that this condition can result from underlying genetic variants that significantly alter the phenotype of vascular smooth muscle cells.
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http://dx.doi.org/10.1016/j.ajhg.2016.11.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5223026PMC
January 2017

Altered Smooth Muscle Cell Force Generation as a Driver of Thoracic Aortic Aneurysms and Dissections.

Arterioscler Thromb Vasc Biol 2017 01 22;37(1):26-34. Epub 2016 Nov 22.

From the Department of Internal Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston (D.M.M., D.-c.G., E.R.); Department of Molecular Physiology and Biophysics, University of Vermont, Burlington (K.M.T.); Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville (H.L.S.); and Department of Physiology, University of Texas Southwestern Medical Center, Dallas (K.K. J.T.S.).

The importance of maintaining contractile function in aortic smooth muscle cells (SMCs) is evident by the fact that heterozygous mutations in the major structural proteins or kinases controlling contraction lead to the formation of aneurysms of the ascending thoracic aorta that predispose to life-threatening aortic dissections. Force generation by SMC requires ATP-dependent cyclic interactions between filaments composed of SMC-specific isoforms of α-actin (encoded by ACTA2) and myosin heavy chain (MYH11). ACTA2 and MYH11 mutations are predicted or have been shown to disrupt this cyclic interaction predispose to thoracic aortic disease. Movement of the myosin motor domain is controlled by phosphorylation of the regulatory light chain on the myosin filament, and loss-of-function mutations in the dedicated kinase for this phosphorylation, myosin light chain kinase (MYLK) also predispose to thoracic aortic disease. Finally, a mutation in the cGMP-activated protein kinase (PRKG1) results in constitutive activation of the kinase in the absence of cGMP, thus driving SMC relaxation in part through increased dephosphorylation of the regulatory light chain and predisposes to thoracic aortic disease. Furthermore, SMCs cannot generate force without connections to the extracellular matrix through focal adhesions, and mutations in the major protein in the extracellular matrix, fibrillin-1, linking SMCs to the matrix also cause thoracic aortic disease in individuals with Marfan syndrome. Thus, disruption of the ability of the aortic SMC to generate force through the elastin-contractile units in response to pulsatile blood flow may be a primary driver for thoracic aortic aneurysms and dissections.
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http://dx.doi.org/10.1161/ATVBAHA.116.303229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5222685PMC
January 2017

Genetic Variants in LRP1 and ULK4 Are Associated with Acute Aortic Dissections.

Am J Hum Genet 2016 09 25;99(3):762-769. Epub 2016 Aug 25.

Department of Internal Medicine, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA. Electronic address:

Acute aortic dissections are a preventable cause of sudden death if individuals at risk are identified and surgically repaired in a non-emergency setting. Although mutations in single genes can be used to identify at-risk individuals, the majority of dissection case subjects do not have evidence of a single gene disorder, but rather have the other major risk factor for dissections, hypertension. Initial genome-wide association studies (GWASs) identified SNPs at the FBN1 locus associated with both thoracic aortic aneurysms and dissections. Here, we used the Illumina HumanExome array to genotype 753 individuals of European descent presenting specifically with non-familial, sporadic thoracic aortic dissection (STAD) and compared them to the genotypes of 2,259 control subjects from the Atherosclerosis Risk in Communities (ARIC) study matched for age, gender, and, for the majority of cases, hypertension. SNPs in FBN1, LRP1, and ULK4 were identified to be significantly associated with STAD, and these results were replicated in two independent cohorts. Combining the data from all cohorts confirmed an inverse association between LRP1 rs11172113 and STAD (p = 2.74 × 10(-8); OR = 0.82, 95% CI = 0.76-0.89) and a direct association between ULK4 rs2272007 and STAD (p = 1.15 × 10(-9); OR = 1.35, 95% CI = 1.23-1.49). Genomic copy-number variation analysis independently confirmed that ULK4 deletions were significantly associated with development of thoracic aortic disease. These results indicate that genetic variations in LRP1 and ULK4 contribute to risk for presenting with an acute aortic dissection.
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http://dx.doi.org/10.1016/j.ajhg.2016.06.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5011062PMC
September 2016

Shared Genetic Risk Factors of Intracranial, Abdominal, and Thoracic Aneurysms.

J Am Heart Assoc 2016 07 14;5(7). Epub 2016 Jul 14.

Surgery Department, University of Otago, Dunedin, New Zealand.

Background: Intracranial aneurysms (IAs), abdominal aortic aneurysms (AAAs), and thoracic aortic aneurysms (TAAs) all have a familial predisposition. Given that aneurysm types are known to co-occur, we hypothesized that there may be shared genetic risk factors for IAs, AAAs, and TAAs.

Methods And Results: We performed a mega-analysis of 1000 Genomes Project-imputed genome-wide association study (GWAS) data of 4 previously published aneurysm cohorts: 2 IA cohorts (in total 1516 cases, 4305 controls), 1 AAA cohort (818 cases, 3004 controls), and 1 TAA cohort (760 cases, 2212 controls), and observed associations of 4 known IA, AAA, and/or TAA risk loci (9p21, 18q11, 15q21, and 2q33) with consistent effect directions in all 4 cohorts. We calculated polygenic scores based on IA-, AAA-, and TAA-associated SNPs and tested these scores for association to case-control status in the other aneurysm cohorts; this revealed no shared polygenic effects. Similarly, linkage disequilibrium-score regression analyses did not show significant correlations between any pair of aneurysm subtypes. Last, we evaluated the evidence for 14 previously published aneurysm risk single-nucleotide polymorphisms through collaboration in extended aneurysm cohorts, with a total of 6548 cases and 16 843 controls (IA) and 4391 cases and 37 904 controls (AAA), and found nominally significant associations for IA risk locus 18q11 near RBBP8 to AAA (odds ratio [OR]=1.11; P=4.1×10(-5)) and for TAA risk locus 15q21 near FBN1 to AAA (OR=1.07; P=1.1×10(-3)).

Conclusions: Although there was no evidence for polygenic overlap between IAs, AAAs, and TAAs, we found nominally significant effects of two established risk loci for IAs and TAAs in AAAs. These two loci will require further replication.
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http://dx.doi.org/10.1161/JAHA.115.002603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5015357PMC
July 2016

FOXE3 mutations predispose to thoracic aortic aneurysms and dissections.

J Clin Invest 2016 Mar 8;126(3):948-61. Epub 2016 Feb 8.

The ascending thoracic aorta is designed to withstand biomechanical forces from pulsatile blood. Thoracic aortic aneurysms and acute aortic dissections (TAADs) occur as a result of genetically triggered defects in aortic structure and a dysfunctional response to these forces. Here, we describe mutations in the forkhead transcription factor FOXE3 that predispose mutation-bearing individuals to TAAD. We performed exome sequencing of a large family with multiple members with TAADs and identified a rare variant in FOXE3 with an altered amino acid in the DNA-binding domain (p.Asp153His) that segregated with disease in this family. Additional pathogenic FOXE3 variants were identified in unrelated TAAD families. In mice, Foxe3 deficiency reduced smooth muscle cell (SMC) density and impaired SMC differentiation in the ascending aorta. Foxe3 expression was induced in aortic SMCs after transverse aortic constriction, and Foxe3 deficiency increased SMC apoptosis and ascending aortic rupture with increased aortic pressure. These phenotypes were rescued by inhibiting p53 activity, either by administration of a p53 inhibitor (pifithrin-α), or by crossing Foxe3-/- mice with p53-/- mice. Our data demonstrate that FOXE3 mutations lead to a reduced number of aortic SMCs during development and increased SMC apoptosis in the ascending aorta in response to increased biomechanical forces, thus defining an additional molecular pathway that leads to familial thoracic aortic disease.
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http://dx.doi.org/10.1172/JCI83778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4767350PMC
March 2016

LOX Mutations Predispose to Thoracic Aortic Aneurysms and Dissections.

Circ Res 2016 Mar 12;118(6):928-34. Epub 2016 Jan 12.

From the Departments of Internal Medicine (D.G., E.S.R., L.G., X.D., Z.R., B.C., E.M.H., D.M.M.) and Cardiothoracic and Vascular Surgery (A.E., H.J.S.), University of Texas Health Science Center, Houston; Department of Molecular and Human Genetics, Center for Statistical Genetics, Baylor College of Medicine, Houston, TX (R.L.P.S.-C., S.M.L.); Laboratory for Vascular Translational Science, INSERM U1148, Hôpital Bichat, Paris, France (P.A., G.J., C.B.); Centre National de Référence pour le syndrome de Marfan et apparentés, Département de Génétique Moléculaire, AP-HP, Hôpital Bichat, Paris, France (P.A., C.B.); Department of Pediatrics, MetroHealth Medical Center, Cleveland, OH (R.M.); Department of Medicine, Stanford University Medical Center, CA (D.L.); and Department of Genome Sciences, University of Washington, Seattle (M.J.B., J.S., D.A.N.).

Rationale: Mutations in several genes have been identified that are responsible for 25% of families with familial thoracic aortic aneurysms and dissections. However, the causative gene remains unknown in 75% of families.

Objectives: To identify the causative mutation in families with autosomal dominant inheritance of thoracic aortic aneurysms and dissections.

Methods And Results: Exome sequencing was used to identify the mutation responsible for a large family with thoracic aortic aneurysms and dissections. A heterozygous rare variant, c.839G>T (p.Ser280Arg), was identified in LOX, encoding a lysyl oxidase, that segregated with disease in the family. Sanger and exome sequencing was used to investigate mutations in LOX in an additional 410 probands from unrelated families. Additional LOX rare variants that segregated with disease in families were identified, including c.125G>A (p.Trp42*), c.604G>T (p.Gly202*), c.743C>T (p.Thr248Ile), c.800A>C (p.Gln267Pro), and c.1044T>A (p.Ser348Arg). The altered amino acids cause haploinsufficiency for LOX or are located at a highly conserved LOX catalytic domain, which is relatively invariant in the population. Expression of the LOX variants p.Ser280Arg and p.Ser348Arg resulted in significantly lower lysyl oxidase activity when compared with the wild-type protein. Individuals with LOX variants had fusiform enlargement of the root and ascending thoracic aorta, leading to ascending aortic dissections.

Conclusions: These data, along with previous studies showing that the deficiency of LOX in mice or inhibition of lysyl oxidases in turkeys and rats causes aortic dissections, support the conclusion that rare genetic variants in LOX predispose to thoracic aortic disease.
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http://dx.doi.org/10.1161/CIRCRESAHA.115.307130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4839295PMC
March 2016

Precision medical and surgical management for thoracic aortic aneurysms and acute aortic dissections based on the causative mutant gene.

J Cardiovasc Surg (Torino) 2016 Apr 2;57(2):172-7. Epub 2016 Feb 2.

Division of Medical Genetics, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA -

Almost one-quarter of patients presenting with thoracic aortic aneurysms (TAAs) or acute aortic dissections (TAADs) have an underlying mutation in a specific gene. A subset of these patients will have systemic syndromic features, for example, skeletal features in patients with Marfan Syndrome. It is important to note that the majority of patients with thoracic aortic disease will not have these syndromic features but many will have a family history of the disease. The genes predisposing to these thoracic aortic diseases are inherited in an autosomal dominant manner, and thirteen genes have been identified to date. As the clinical phenotype associated with each specific gene is defined, the data indicate that the underlying gene dictates associated syndromic features. More importantly, the underlying gene also dictates the aortic disease presentation, the risk for dissection at a given range of aortic diameters, the risk for additional vascular diseases and what specific vascular diseases occur associated with the gene. These results lead to the recommendation that the medical and surgical management of these patients be dictated by the underlying gene, and for patients with mutations in ACTA2, the specific mutation in the gene.
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April 2016

SMAD2 Mutations Are Associated with Arterial Aneurysms and Dissections.

Hum Mutat 2015 Dec 10;36(12):1145-9. Epub 2015 Sep 10.

Department of Clinical Genetics, Center for Connective Tissue Research, VU University Medical Center, Amsterdam, 1007, MB, The Netherlands.

We report three families with arterial aneurysms and dissections in which variants predicted to be pathogenic were identified in SMAD2. Moreover, one variant occurred de novo in a proband with unaffected parents. SMAD2 is a strong candidate gene for arterial aneurysms and dissections given its role in the TGF-β signaling pathway. Furthermore, although SMAD2 and SMAD3 probably have functionally distinct roles in cell signaling, they are structurally very similar. Our findings indicate that SMAD2 mutations are associated with arterial aneurysms and dissections and are in accordance with the observation that patients with pathogenic variants in genes encoding proteins involved in the TGF-β signaling pathway exhibit arterial aneurysms and dissections as key features.
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http://dx.doi.org/10.1002/humu.22854DOI Listing
December 2015

Aortic Disease Presentation and Outcome Associated With ACTA2 Mutations.

Circ Cardiovasc Genet 2015 Jun 10;8(3):457-64. Epub 2015 Mar 10.

Departments of Internal Medicine (E.S.R., D.G., S.P., T.A.B., K.F., D.M.M.), Cardiothoracic and Vascular Surgery (A.E., H.S.), University of Texas Health Science Center at Houston; Department of Medicine, Stanford University Medical Center, CA (D.L.); Connective Tissue Gene Tests, Allentown, PA (J.H.); Department of Cardiac and Vascular Sciences, St. George's, University of London, London, United Kingdom (A.C., G.A.); AP-HP, Hôpital Bichat, Centre National de Référence pour le syndrome de Marfan et apparentés, Paris, France (C.B., G.J.), Université Paris 7, Paris, France (C.B., G.J.), AP-HP, Hôpital Bichat, Laboratoire de Génétique moléculaire, Boulogne, France (C.B.), and INSERM, U1148, Paris, France (C.B., G.J.); AP-HP, Hôpital Bichat, Service de Cardiologie, Paris, France (G.J.); Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO (A.B.); Genomic Medicine Institute, Cleveland Clinic, OH (R.M.); Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan (T.M., H.M.); Perelman School of Medicine, University of Pennsylvania, Philadelphia (R.P.); Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX (J.C., S.L.); and Texas Heart Institute and Baylor St. Luke's Medical Center, Houston (J.C., S.L.).

Background: ACTA2 mutations are the major cause of familial thoracic aortic aneurysms and dissections. We sought to characterize these aortic diseases in a large case series of individuals with ACTA2 mutations.

Methods And Results: Aortic disease, management, and outcome associated with the first aortic event (aortic dissection or aneurysm repair) were abstracted from the medical records of 277 individuals with 41 various ACTA2 mutations. Aortic events occurred in 48% of these individuals, with the vast majority presenting with thoracic aortic dissections (88%) associated with 25% mortality. Type A dissections were more common than type B dissections (54% versus 21%), but the median age of onset of type B dissections was significantly younger than type A dissections (27 years versus 36 years). Only 12% of aortic events were repair of ascending aortic aneurysms, which variably involved the aortic root, ascending aorta, and aortic arch. Overall, cumulative risk of an aortic event at age 85 years was 0.76 (95% confidence interval, 0.64-0.86). After adjustment for intrafamilial correlation, sex and race, mutations disrupting p.R179 and p.R258 were associated with significantly increased risk for aortic events, whereas p.R185Q and p.R118Q mutations showed significantly lower risk of aortic events compared with other mutations.

Conclusions: ACTA2 mutations are associated with high risk of presentation with an acute aortic dissection. The lifetime risk for an aortic event is only 76%, suggesting that additional environmental or genetic factors play a role in expression of aortic disease in individuals with ACTA2 mutations.
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http://dx.doi.org/10.1161/CIRCGENETICS.114.000943DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4601641PMC
June 2015

MAT2A mutations predispose individuals to thoracic aortic aneurysms.

Am J Hum Genet 2015 Jan 31;96(1):170-7. Epub 2014 Dec 31.

Department of Internal Medicine, University of Texas Health Science Center, Houston, TX 77030, USA. Electronic address:

Up to 20% of individuals who have thoracic aortic aneurysms or acute aortic dissections but who do not have syndromic features have a family history of thoracic aortic disease. Significant genetic heterogeneity is established for this familial condition. Whole-genome linkage analysis and exome sequencing of distant relatives from a large family with autosomal-dominant inheritance of thoracic aortic aneurysms variably associated with the bicuspid aortic valve was used for identification of additional genes predisposing individuals to this condition. A rare variant, c.1031A>C (p.Glu344Ala), was identified in MAT2A, which encodes methionine adenosyltransferase II alpha (MAT IIα). This variant segregated with disease in the family, and Sanger sequencing of DNA from affected probands from unrelated families with thoracic aortic disease identified another MAT2A rare variant, c.1067G>A (p.Arg356His). Evidence that these variants predispose individuals to thoracic aortic aneurysms and dissections includes the following: there is a paucity of rare variants in MAT2A in the population; amino acids Glu344 and Arg356 are conserved from humans to zebrafish; and substitutions of these amino acids in MAT Iα are found in individuals with hypermethioninemia. Structural analysis suggested that p.Glu344Ala and p.Arg356His disrupt MAT IIα enzyme function. Knockdown of mat2aa in zebrafish via morpholino oligomers disrupted cardiovascular development. Co-transfected wild-type human MAT2A mRNA rescued defects of zebrafish cardiovascular development at significantly higher levels than mRNA edited to express either the Glu344 or Arg356 mutants, providing further evidence that the p.Glu344Ala and p.Arg356His substitutions impair MAT IIα function. The data presented here support the conclusion that rare genetic variants in MAT2A predispose individuals to thoracic aortic disease.
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http://dx.doi.org/10.1016/j.ajhg.2014.11.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4289682PMC
January 2015

MFAP5 loss-of-function mutations underscore the involvement of matrix alteration in the pathogenesis of familial thoracic aortic aneurysms and dissections.

Am J Hum Genet 2014 Dec 26;95(6):736-43. Epub 2014 Nov 26.

INSERM U1148, Laboratory for Vascular Translational Science, Hôpital Bichat, Université Paris Diderot, Sorbonne Paris Cité, 75018 Paris, France; AP-HP, Département de Génétique, Hôpital Bichat, 75018 Paris, France; AP-HP, Centre de référence pour les syndromes de Marfan et apparentés, Service de Cardiologie, Hôpital Bichat, 75018 Paris, France; UFR de Médecine, Université Paris Diderot, 75018 Paris, France. Electronic address:

Thoracic aortic aneurysm and dissection (TAAD) is an autosomal-dominant disorder with major life-threatening complications. The disease displays great genetic heterogeneity with some forms allelic to Marfan and Loeys-Dietz syndrome, and an important number of cases still remain unexplained at the molecular level. Through whole-exome sequencing of affected members in a large TAAD-affected family, we identified the c.472C>T (p.Arg158(∗)) nonsense mutation in MFAP5 encoding the extracellular matrix component MAGP-2. This protein interacts with elastin fibers and the microfibrillar network. Mutation screening of 403 additional probands identified an additional missense mutation of MFAP5 (c.62G>T [p.Trp21Leu]) segregating with the disease in a second family. Functional analyses performed on both affected individual's cells and in vitro models showed that these two mutations caused pure or partial haploinsufficiency. Thus, alteration of MAGP-2, a component of microfibrils and elastic fibers, appears as an initiating mechanism of inherited TAAD.
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http://dx.doi.org/10.1016/j.ajhg.2014.10.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259978PMC
December 2014

Acute aortic dissections with pregnancy in women with ACTA2 mutations.

Am J Med Genet A 2014 Jan 15;164A(1):106-12. Epub 2013 Nov 15.

Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas.

Mutations in ACTA2 predispose to thoracic aortic aneurysms and dissection as well as coronary artery and cerebrovascular disease. Here we examined the risk of aortic dissections, stroke and myocardial infarct with pregnancy in women with ACTA2 mutations. Of the 53 women who had a total of 137 pregnancies, eight had aortic dissections in the third trimester or the postpartum period (6% of pregnancies). One woman also had a myocardial infarct that occurred during pregnancy that was independent of her aortic dissection. Compared to the population-based frequency of peripartum aortic dissections of 0.6%, the rate of peripartum aortic dissections in women with ACTA2 mutations is much higher (8 out of 39; 20%). Six of these dissections initiated in the ascending aorta (Stanford type A), three were fatal. Three women had ascending aortic dissections at diameters less that 5.0 cm (range 3.8-4.7 cm). Aortic pathology showed mild to moderate medial degeneration of the aorta in three women. Of note, five of the women had hypertension either during or before the pregnancy. In summary, the majority of women with ACTA2 mutations did not have aortic or other vascular complications with pregnancy. However, these findings show that pregnancy is associated with significant risk for aortic dissection in women with ACTA2 mutations. Women with ACTA2 mutations who are planning to get pregnant should be counseled about this risk of aortic dissection, and proper clinical management should be initiated to reduce this risk.
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http://dx.doi.org/10.1002/ajmg.a.36208DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012224PMC
January 2014

Successes and challenges of using whole exome sequencing to identify novel genes underlying an inherited predisposition for thoracic aortic aneurysms and acute aortic dissections.

Trends Cardiovasc Med 2014 Feb 15;24(2):53-60. Epub 2013 Aug 15.

Division of Medical Genetics, Department of Internal Medicine, University of Texas Health Science Center at Houston (UT Health), 6431 Fannin, Suite 6.100, Houston, TX 77030, USA.

Thoracic aortic aneurysms involving the aortic root and/or ascending aorta can lead to acute aortic dissections. Approximately 20% of patients with thoracic aortic aneurysms and dissections (TAAD) have a family history of the disease, referred to as familial TAAD (FTAAD) that can be inherited in an autosomal dominant manner with variable expression with respect to disease presentation, age of onset and associated features. Whole exome sequencing (WES) has been used to identify causative mutations in novel genes for TAAD. The strategy used to reduce the large number of rare variants identified using WES is to sequence distant relatives with TAAD and filter for heterozygous rare variants that are shared between the relatives, predicted to disrupt protein function and segregate with the TAAD phenotype in other family members. Putative genes are validated by identifying additional families with a causative mutation in the genes. This approach has successfully identified novel genes for FTAAD.
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http://dx.doi.org/10.1016/j.tcm.2013.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3917689PMC
February 2014

Recurrent gain-of-function mutation in PRKG1 causes thoracic aortic aneurysms and acute aortic dissections.

Am J Hum Genet 2013 Aug 1;93(2):398-404. Epub 2013 Aug 1.

Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.

Gene mutations that lead to decreased contraction of vascular smooth-muscle cells (SMCs) can cause inherited thoracic aortic aneurysms and dissections. Exome sequencing of distant relatives affected by thoracic aortic disease and subsequent Sanger sequencing of additional probands with familial thoracic aortic disease identified the same rare variant, PRKG1 c.530G>A (p.Arg177Gln), in four families. This mutation segregated with aortic disease in these families with a combined two-point LOD score of 7.88. The majority of affected individuals presented with acute aortic dissections (63%) at relatively young ages (mean 31 years, range 17-51 years). PRKG1 encodes type I cGMP-dependent protein kinase (PKG-1), which is activated upon binding of cGMP and controls SMC relaxation. Although the p.Arg177Gln alteration disrupts binding to the high-affinity cGMP binding site within the regulatory domain, the altered PKG-1 is constitutively active even in the absence of cGMP. The increased PKG-1 activity leads to decreased phosphorylation of the myosin regulatory light chain in fibroblasts and is predicted to cause decreased contraction of vascular SMCs. Thus, identification of a gain-of-function mutation in PRKG1 as a cause of thoracic aortic disease provides further evidence that proper SMC contractile function is critical for maintaining the integrity of the thoracic aorta throughout a lifetime.
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http://dx.doi.org/10.1016/j.ajhg.2013.06.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3738837PMC
August 2013

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

Am J Med Genet A 2013 Sep 29;161A(9):2305-10. Epub 2013 Jul 29.

Department of Internal Medicine, Division of Medical Genetics, University of Texas Health Science Center at Houston, Texas, USA.

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.
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http://dx.doi.org/10.1002/ajmg.a.36044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3829633PMC
September 2013

Interleukin-6-signal transducer and activator of transcription-3 signaling mediates aortic dissections induced by angiotensin II via the T-helper lymphocyte 17-interleukin 17 axis in C57BL/6 mice.

Arterioscler Thromb Vasc Biol 2013 Jul 16;33(7):1612-21. Epub 2013 May 16.

Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.

Objective: Dysregulated angiotensin II (Ang II) signaling induces local vascular interleukin-6 (IL-6) secretion, producing leukocyte infiltration and life-threatening aortic dissections. Precise mechanisms by which IL-6 signaling induces leukocyte recruitment remain unknown. T-helper 17 lymphocytes (Th17) have been implicated in vascular pathology, but their role in the development of aortic dissections is poorly understood. Here, we tested the relationship of IL-6-signal transducer and activator of transcription-3 signaling with Th17-induced inflammation in the formation of Ang II-induced dissections in C57BL/6 mice.

Approach And Results: Ang II infusion induced aortic dissections and CD4(+)-interleukin 17A (IL-17A)-expressing Th17 cell accumulation in C57BL/6 mice. A blunted local Th17 activation, macrophage recruitment, and reduced incidence of aortic dissections were seen in IL-6(-/-) mice. To determine the pathological roles of Th17 lymphocytes, we treated Ang II-infused mice with IL-17A-neutralizing antibody or infused Ang II in genetically deficient IL-17A mice and found decreased aortic chemokine monocytic chemotactic protein-1 production and macrophage recruitment, leading to a reduction in aortic dissections. This effect was independent of blood pressure in IL-17A-neutralizing antibody experiment. Application of a cell-permeable signal transducer and activator of transcription-3 inhibitor to downregulate the IL-6 pathway decreased aortic dilation and Th17 cell recruitment. We also observed increased aortic Th17 infiltration and IL-17 mRNA expression in patients with thoracic aortic dissections. Finally, we found that Ang II-mediated aortic dissections occurred independent of blood pressure changes.

Conclusions: Our results indicate that the IL-6-signal transducer and activator of transcription-3 signaling pathway converges on Th17 recruitment and IL-17A signaling upstream of macrophage recruitment, mediating aortic dissections.
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http://dx.doi.org/10.1161/ATVBAHA.112.301049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3818154PMC
July 2013

TGFB2 mutations cause familial thoracic aortic aneurysms and dissections associated with mild systemic features of Marfan syndrome.

Nat Genet 2012 Jul 8;44(8):916-21. Epub 2012 Jul 8.

Institut National de la Santé et de la Recherche Médicale (INSERM) U698, Hôpital Bichat, Paris, France.

A predisposition for thoracic aortic aneurysms leading to acute aortic dissections can be inherited in families in an autosomal dominant manner. Genome-wide linkage analysis of two large unrelated families with thoracic aortic disease followed by whole-exome sequencing of affected relatives identified causative mutations in TGFB2. These mutations-a frameshift mutation in exon 6 and a nonsense mutation in exon 4-segregated with disease with a combined logarithm of odds (LOD) score of 7.7. Sanger sequencing of 276 probands from families with inherited thoracic aortic disease identified 2 additional TGFB2 mutations. TGFB2 encodes transforming growth factor (TGF)-β2, and the mutations are predicted to cause haploinsufficiency for TGFB2; however, aortic tissue from cases paradoxically shows increased TGF-β2 expression and immunostaining. Thus, haploinsufficiency for TGFB2 predisposes to thoracic aortic disease, suggesting that the initial pathway driving disease is decreased cellular TGF-β2 levels leading to a secondary increase in TGF-β2 production in the diseased aorta.
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http://dx.doi.org/10.1038/ng.2348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033668PMC
July 2012

Exogenous visual orienting is associated with specific neurotransmitter genetic markers: a population-based genetic association study.

PLoS One 2012 14;7(2):e30731. Epub 2012 Feb 14.

Psychology Department, Rice University, Houston, Texas, United States of America.

Background: Currently, there is a sense that the spatial orienting of attention is related to genotypic variations in cholinergic genes but not to variations in dopaminergic genes. However, reexamination of associations with both cholinergic and dopaminergic genes is warranted because previous studies used endogenous rather than exogenous cues and costs and benefits were not analyzed separately. Examining costs (increases in response time following an invalid pre-cue) and benefits (decreases in response time following a valid pre-cue) separately could be important if dopaminergic genes (implicated in disorders such as attention deficit disorder) independently influence the different processes of orienting (e.g., disengage, move, engage).

Methodology/principal Findings: We tested normal subjects (N = 161) between 18 and 61 years. Participants completed a computer task in which pre-cues preceded the presence of a target. Subjects responded (with a key press) to the location of the target (right versus left of fixation). The cues could be valid (i.e., appear where the target would appear) or invalid (appear contralateral to where the target would appear). DNA sequencing assays were performed on buccal cells to genotype known genetic markers and these were examined for association with task scores. Here we show significant associations between visual orienting and genetic markers (on COMT, DAT1, and APOE; R(2)s from 4% to 9%).

Conclusions/significance: One measure in particular--the response time cost of a single dim, invalid cue - was associated with dopaminergic markers on COMT and DAT1. Additionally, variations of APOE genotypes based on the ε2/ε3/ε4 alleles were also associated with response time differences produced by simultaneous cues with unequal luminances. We conclude that individual differences in visual orienting are related to several dopaminergic markers as well as to a cholinergic marker. These results challenge the view that orienting is not associated with genotypic variation in dopaminergic genes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030731PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279352PMC
July 2012
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