Analysis of positional candidate genes in the AAA1 susceptibility locus for abdominal aortic aneurysms on chromosome 19
© Lillvis et al; licensee BioMed Central Ltd. 2011
Received: 9 August 2010
Accepted: 19 January 2011
Published: 19 January 2011
Abdominal aortic aneurysm (AAA) is a complex disorder with multiple genetic risk factors. Using affected relative pair linkage analysis, we previously identified an AAA susceptibility locus on chromosome 19q13. This locus has been designated as the AAA1 susceptibility locus in the Online Mendelian Inheritance in Man (OMIM) database.
Nine candidate genes were selected from the AAA1 locus based on their function, as well as mRNA expression levels in the aorta. A sample of 394 cases and 419 controls was genotyped for 41 SNPs located in or around the selected nine candidate genes using the Illumina GoldenGate platform. Single marker and haplotype analyses were performed. Three genes (CEBPG, PEPD and CD22) were selected for DNA sequencing based on the association study results, and exonic regions were analyzed. Immunohistochemical staining of aortic tissue sections from AAA and control individuals was carried out for the CD22 and PEPD proteins with specific antibodies.
Several SNPs were nominally associated with AAA (p < 0.05). The SNPs with most significant p-values were located near the CCAAT enhancer binding protein (CEBPG), peptidase D (PEPD), and CD22. Haplotype analysis found a nominally associated 5-SNP haplotype in the CEBPG/PEPD locus, as well as a nominally associated 2-SNP haplotype in the CD22 locus. DNA sequencing of the coding regions revealed no variation in CEBPG. Seven sequence variants were identified in PEPD, including three not present in the NCBI SNP (dbSNP) database. Sequencing of all 14 exons of CD22 identified 20 sequence variants, five of which were in the coding region and six were in the 3'-untranslated region. Five variants were not present in dbSNP. Immunohistochemical staining for CD22 revealed protein expression in lymphocytes present in the aneurysmal aortic wall only and no detectable expression in control aorta. PEPD protein was expressed in fibroblasts and myofibroblasts in the media-adventitia border in both aneurysmal and non-aneurysmal tissue samples.
Association testing of the functional positional candidate genes on the AAA1 locus on chromosome 19q13 demonstrated nominal association in three genes. PEPD and CD22 were considered the most promising candidate genes for altering AAA risk, based on gene function, association evidence, gene expression, and protein expression.
Abdominal aortic aneurysm (AAA) is an irreversible, progressive dilation of the abdominal aorta, occurring most frequently below the renal arteries. Known risk factors for AAA include smoking, male sex, comorbid vascular disease, increasing age, and family history . AAA pathophysiology is complex, but fundamentally aneurysms arise from the loss of structural integrity and the consequent weakening of the vessel wall. Several extracellular matrix (ECM) degrading enzymes, including matrix metallopeptidases (MMPs) , cathepsins [3, 4], and granzyme , have been implicated in the destruction and turnover of ECM proteins in the aortic wall. Infiltrating cells of the immune system are also found throughout the AAA wall  and are important to AAA development by producing ECM degrading enzymes and reactive oxygen species, as well as releasing proinflammatory cytokines that lead to further inflammation [7, 8].
AAA also displays several characteristics consistent with being a multifactorial genetic disease . Approximately 15% of AAA patients have a positive family history  and genetic association studies have identified risk alleles in cardiovascular risk genes such as DAB2IP , CDKN2BAS , AGTR1 [13, 14], ACE [13, 14], and MTHFR . These polymorphisms, however, explain only a small fraction of an individual's genetic risk for AAA. A genome-wide DNA linkage analysis using an affected relative pair approach with covariates by our laboratory identified two linked chromosomal regions on 19q13 and 4q31 . Linkage to chromosome 19q was replicated in a separate study in Dutch families using different statistical analyses . Chromosome 19q13 may harbour risk alleles for several aneurysm phenotypes, as linkage to this region has also been reported for intracranial aneurysms [17–19] and the Kawasaki disease .
Several functional candidate genes reside within the chromosome 19 candidate interval. Peptidase D (PEPD; prolidase) is a manganese-dependent dipeptidyl peptidase that cleaves iminopeptides with C-terminal proline or hydroxyproline, which is the terminal step in collagen degradation . The chromosome 19q candidate interval also contains several genes that may be relevant to immune system function in AAA. CD22 is a sialic-acid binding protein expressed in B-lymphocytes, which can inhibit signalling through the B-cell receptor and therefore alter B-cell function . B-cells are found in the AAA wall and CD22 has been implicated in autoimmune pathologies characterized by similar inflammatory and ECM changes seen in some AAAs .
Here we report on an analysis of candidate genes selected from the chromosome 19q13 linkage interval. Nine functional positional candidate genes (PEPD, CEBPA, CEBPG, GPI, HAMP, CD22, NFKBID, TYROBP, and HCST) were identified as having annotated function in either the immune system or in ECM turnover. Fifty-five SNPs covering the major haplotype blocks in each gene were selected. Two genes with evidence of association, CD22 and PEPD, were investigated further by exon sequencing and immunohistochemical staining of aneurysmal and non-aneurysmal aortic tissue samples.
Human samples for genotyping
AAA cases used in genotyping (n = 394; 79% male) were collected at the University of Pittsburgh, the University of Liége in Liége, Belgium, and Dalhousie University Hospital in Nova Scotia, Canada. Canadian controls were spouses of AAA cases. Belgian controls were patients with diagnoses other than AAA and treated at the same hospital as the AAA cases. Details on the recruitment have been published previously and the samples have been used in prior genetic association studies [12, 24, 25]. The collection of samples was approved by the Institutional Review Board of Wayne State University and each recruitment site.
DNA isolation and whole genome amplification (WGA)
Genomic DNA used in genotyping and sequencing was isolated from peripheral blood as described previously . A total of 10 ng of genomic DNA was amplified by strand-displacement amplification  with Phi29 polymerase using the Genomiphi Kit (GE Healthcare Biosciences, Piscataway, NJ) according to the manufacturer's instructions. Amplified DNA was diluted 1:100 for use in genotyping and DNA sequencing reactions.
RNA isolation and cDNA synthesis
Total RNA was isolated from cultured skin fibroblasts as previously described . cDNA was prepared from 250 ng of RNA using SuperScript III First-Strand Synthesis Supermix (Invitrogen, Carlsbad, CA). Residual RNA was removed by RNAse H treatment.
Genetic association study
Genes in the linkage interval on chromosome 19 were prioritized functionally using Gene Ontology (GO)  and Kyoto Encyclopedia of Genes and Genomes (KEGG)  annotations. mRNA expression of each gene in AAA and control abdominal aorta was also assessed using data from a previously described microarray-based mRNA expression profiling study . Altogether 55 SNPs with a minor allele frequency (MAF) of 0.10 or greater that were representative of major haplotype blocks in the Caucasian population were identified in and around the nine positional functional candidate genes selected for the study. Each SNP was assessed for its SNP quality score from Illumina and a custom Illumina BeadChip was designed using those SNPs considered to have sufficient designability. The SNPs are listed in Additional file 1, Table S1.
Power calculations were performed using the Genetic Power Calculator  (http://pngu.mgh.harvard.edu/~purcell/gpc/). We assumed that the polymorphism and the disease locus were in complete linkage disequilibrium (LD) and that they had the same allele frequencies, i.e., the polymorphism was the disease locus. Assuming a disease locus with an additive effect and a disease prevalence of 0.02, our sample size of 394 cases and 419 controls had an 80% power to detect a susceptibility locus with a genotypic relative risk (GRR) ≥ 1.2 (2.4 for two copies of risk alleles) at a significance level of 0.05 for a SNP with a high risk allele frequency (HAF) ≥ 0.2.
SNPs were genotyped using the Illumina GoldenGate assay  and the call rate of each SNP was evaluated using GenCall Software (version 22.214.171.124, Illumina, San Diego, CA). Deviation from Hardy-Weinberg equilibrium (HWE) was evaluated using an exact test  as implemented in Haploview  and nominal p-values without correction for multiple testing are reported in Additional File 1. Allelic association was tested using a Pearson χ2 test with one degree of freedom (DF). To assess the potential for population stratification, HWE and allelic association were also tested separately in the Belgian and Canadian subpopulations. An additional test of association was performed using the general linear mixed model approach implemented in the Statistical Analysis for Genetic Epidemiology (S.A.G.E.)  program ASSOC, which yields both Wald and likelihood ratio test (LRT) statistics. Both tests gave very similar results and therefore, we report only results from the LRT which is considered more robust in small sample sizes. False discovery rates (FDR) are reported for the LRT. Haplotype association was analyzed using a score test  implemented in the haplo.score function in the package HaploStats for the R statistical language and environment . For genes with evidence of association, LD plots were generated from the case and control genotypes separately using HaploView to examine LD structure.
DNA sequencing of functional positional candidate genes
Genomic DNA and RNA samples used in DNA sequencing are listed in Additional files 2 (Table S2) and 3 (Table S3). Primer pairs to amplify the coding sequence of CEBPG, cDNA sequence of PEPD, and exonic sequences of CD22 were designed using PrimerQuestSM, a primer design tool based on Primer3 software  available on the Integrated DNA Technologies website (http://www.idtdna.com/Scitools/Applications/Primerquest/; IDT, Coralville, IA). Primers were selected using predicted melting points, primer hairpins and primer-dimer interactions calculated using the SciTools programs in PrimerQuestSM. DNA amplification by PCR was performed under the following conditions. Final concentrations were 50 mM KCl, 1.5 or 2 mM MgCl2 (primer-pair specific; see Additional file 4, Table S4), 2 μM dNTPs, 0.167 μM of each primer, 0.025 U/μl AmpliTaq Gold enzyme (Applied Biosystems) in 10 mM Tris-HCl, pH 8.3. Template DNA constituted 1/10th of the final volume for WGA-genomic DNA or 1/20th for cDNA. Template was denatured by heating to 94°C for 10 minutes, which was followed by 40 cycles of denaturation (94°C), annealing (variable) and elongation (72°C), and a final three-minute elongation incubation at 72°C. Detailed cycle times and annealing temperatures are found in Additional file 4, Table S4.
PCR products were separated by agarose gel electrophoresis to assess the sizes of bands and the specificity of the reaction. PCR products with single clean bands of the correct molecular weight were purified for DNA sequencing using Montage™ PCR purification columns (Millipore, Billerica, MA).
DNA sequencing was performed using the Cycle Sequencing (Applied Biosystems, Foster City, CA) method at the Applied Genomics Technology Center (AGTC) at Wayne State University. Primers used for DNA sequencing can be found in Additional file 5, Table S5. Sequence variants were identified by alignment of sequences using BioX software (available at https://www.lagercrantz.name/projects/biox) and manual examination of the sequence plots.
Functional analysis of sequence variants
To assess the potential function of identified sequence variants, in silico functional analyses were carried out. The SIFT (Sorting Intolerant from Tolerant) algorithm  was used to predict the structural effects of non-synonymous substitutions. NetPhos  was used to predict the creation or destruction of phosphorylation sites. To assess the potential effect of 3'-untranslated region (UTR) sequence variants on microRNA (miRNA) binding, predicted binding sites were obtained from the MicroCosm Targets Database [40, 41] (http://www.ebi.ac.uk/enright-srv/microcosm/htdocs/targets/v5/).
Immunohistochemical staining to analyze protein expression in human aortic tissues
Control non-aneurysmal aortas (n = 7) were obtained post-mortem at autopsy. Exclusion criteria were known malignancy or systemic infection. AAA tissues (n = 9) were obtained from elective surgical repair operations when the aneurysmal sac was trimmed as part of surgery. Tissue samples were removed solely for the purpose of graft placement and would otherwise be discarded. Tonsil (for CD22) or kidney (for PEPD) tissue were used as positive controls. Nonspecific IgG in lieu of primary antibody served as a negative control. All tissue samples were fixed in buffered formalin solution, routinely processed and then embedded in paraffin. Details on aortic samples used can be found in Additional file 6: Table S6.
Immunohistochemical staining was carried out using 5 μm sections of formalin-fixed paraffin embedded aortic tissue. Sections were dried in an oven and deparaffinized using sequential rinses in Histoclear xylene substitute (National Diagnostics U.S.A., Atlanta, GA), 100% ethanol, 95% ethanol and water. Heat-induced antigen retrieval was performed by microwave-treatment of slides submerged in citrate buffer. Endogenous peroxidase was blocked by placing slides in 3% methanol/peroxide block solution for 10 min. The slides were incubated with primary antibody directed against PEPD (1:250 dilution; catalog number 12218-1-AP, Proteintech Group, Inc., Chicago, IL) or CD22 (1:100 dilution; catalog number ab953, Abcam Inc., Cambridge, MA) on an automatic immunostainer (Autostainer, DAKO, Carpinteria, CA). A secondary antibody with avidin-biotin peroxidase amplification from DAKO was used and the signal detected using diaminobenzidine as a chromogen.
Selection of functional candidate genes on AAA1 locus
Functional positional candidate genes studied by genetic association
immune response; others
myeloid cell differentiation
humoral immune response
immune response; others
immune response; others
B-cell receptor signaling pathway
cellular defense response
natural killer cell mediated cytotoxicity
natural killer cell mediated cytotoxicity
Since genes not expressed in aortic tissue, either diseased or non-diseased, would be less likely to contribute to aneurysm formation, mRNA expression of each candidate gene was assessed using microarray expression profiles of AAA and control aortic tissue. As all of the genes selected by functional annotation were expressed in either AAA or control abdominal aorta, no genes were excluded by this criterion. Furthermore, four of these genes, CEBPA, NFKBID, HCST and TYROBP, had significantly higher expression in AAA tissue than in age-, sex-, and ethnicity-matched control aortas and CD22 was expressed only in AAA tissue (Table 1).
Candidate gene association study
Fifty-five SNPs in or around the nine functional candidate genes found in the AAA1 locus were genotyped. Eleven SNPs were excluded from further analysis since they were either monomorphic or had low genotype call rates (Additional file 1, Table S1). This number can be considered high, but is expected in a custom array where several of the SNP assays had not been previously validated. Additionally, the excluded SNPs were located in CEPBA and PEPD, where the genotyping coverage was excellent even without including the failed assays. Testing for deviation from HWE was performed in the remaining 44 SNPs and four SNPs (rs7248389, rs752237, rs736289 and rs4239576) that showed deviation were identified (Additional file 1, Table S1). One of the four SNPs also showed evidence of association and since deviation from HWE can result from association, this SNP (rs7248389) was included in the final analysis. Three of the four SNPs did not show evidence of association, and were subsequently excluded (rs752237, rs736289 and rs4239576) from further analysis leaving 41 SNPs for the final analyses. In the cases of these three variants the deviation from HWE was likely due to technical problems in genotyping.
Genetic association study results for SNPs with nominal p < 0.05.
MAF (Cases; Controls)
Since there were multiple associated SNPs in PEPD and CD22, the LD structure of the genotyped SNPs in each gene was examined using LD plots (Additional file 7, Figure S1 and Additional file 8, Figure S2).
To identify population-specific effects, allelic association was evaluated in the Canadian and Belgian subpopulations separately (Table 2). For a majority of the SNPs identified above, evidence of association was stronger in the Canadian subpopulation. Four SNPs (rs2267574, rs7248389, rs889140, and rs7251432) were nominally associated in the Canadian subpopulation, but only one of these (rs7248389) showed evidence for association in the Belgian subpopulation. One associated SNP located in PEPD (rs7248389) showed nominal deviation from HWE. All nominally associated SNPs and their p-values for the different tests are summarized in Table 2.
Significantly associated haplotypes in PEPD and CD22 genes
Gene and SNPs in the haplotype
Frequency in cases
Frequency in controls
OR [95% CI]
1.049 [0.761, 1.445]
1.062 [0.687, 1.644]
1.422 [0.997, 2.028]
1.872 [0.745, 4.706]
1.512 [1.020, 2.242]
1.435 [1.087, 1.894]
1.253 [0.995, 1.577]
DNA sequencing of exons in candidate genes with putative association
Three genes, CD22, CEBPG, and PEPD, were chosen for DNA sequencing. No significantly associated SNPs were detected within CEBPG, but it was chosen for sequencing since it is in close proximity to PEPD and could plausibly contribute to the association signal detected in that gene. CD22 was also considered an intriguing candidate gene since it was expressed in AAA tissue and its expression was not detectable in non-aneurysmal abdominal aorta.
Since the functional consequences associated with exon sequence changes are often easier to predict than with intronic sequences, exon sequencing covering a minimum of the protein coding regions of each gene was performed. The protein coding region of CEPBG was sequenced from the genomic DNA of 21 AAA cases, 10 familial and 11 sporadic, and two controls. CEBPG has a large 3'-UTR that we chose not to sequence because of the relatively weak evidence for association within the gene. No sequence variants were identified within the regions sequenced and therefore no further analysis was pursued with this gene.
Sequence changes detected by cDNA sequencing of PEPD
Chr. Pos. (Build 37)1
T- > C
Y- > Y
T- > C
G- > G
C- > T
H- > H
C- > T
H- > H
G- > A
A- > T
C- > T
L- > F
G- > T
L- > L
Three of the PEPD sequence variants identified were novel, in that they were not in either the dbSNP or Celera databases. Two SNPs coded for non-synonymous amino acid changes: rs17570, which results in a leucine to phenylalanine substitution at amino acid position 435, and a novel variant resulting in an alanine to threonine substitution at amino acid 432 (Table 4).
Sequence changes detected by CD22 exon sequencing
Chr. Pos. (Build 37)
C- > T
C- > G
A- > G
C- > T
C- > C
G- > A
R- > K
T- > A
C- > T
A- > G
R- > G
G- > A
G- > D
C- > A
P- > P
G- > A
C- > T
C- > T
G- > A
C- > T
A- > G
C- > T
C- > T
C- > T
Three of the sequence variants identified in the CD22 were non-synonymous (R > K, R > G and G > D) amino acid changes (Table 5). Two of the three were very rare (MAF = 0.02), whereas one (rs10406069) had a MAF = 0.104. We tested this variant for genetic association in our case-control set, but found no differences in the allele or genotype frequencies between cases and controls.
Predicted functional changes
Several in silico analyses were used to predict whether any of the observed sequence changes might alter protein function or regulation of gene expression. To assess the potential effect of non-synonymous amino acid substitutions, each sequence variant was analyzed with the SIFT algorithm, which predicts whether amino acid changes will not be tolerated. SIFT predicted that all five amino acid substitutions coded by the sequence variants identified in CD22 and PEPD would be tolerated. Structural modeling of PEPD demonstrated that the identified amino acid substitutions A432T and L435F, resided in close proximity in a region that appeared to tolerate structural changes (not shown).
The 3'-UTR of many genes acts as a binding site for miRNAs in post-transcriptional gene regulation . To find out if any of the six sequence variants identified in the 3'-UTR of CD22 might interrupt miRNA binding, predicted miRNA binding sites were obtained from MicroCosm database. We found no evidence that the variants changed the binding sites of any miRNAs (not shown).
CD22 and PEPD proteins are expressed in aortic wall
Strong evidence of linkage exists on chromosome 19 in the AAA1 locus [15, 16], but no specific risk loci have yet been discovered. We identified nine functional positional candidate genes within this interval for further study by genetic association. Two of these, PEPD and CD22, showed evidence of nominal association in multiple SNPs, although only one SNP remained significant after correction for multiple testing. Additionally, significant five- and two-SNP haplotypes were identified for PEPD and CD22, respectively.
Evidence of association in PEPD and CD22, was of considerable interest. Based on gene function, gene expression, and protein expression, these genes are plausible candidates for contributing to the risk of developing an AAA. The role of PEPD in collagen metabolism makes it a strong functional candidate for AAA. Although it is unlikely that complete loss of PEPD function alters AAA risk, given that it results in the severe phenotype of prolidase deficiency, polymorphisms that alter PEPD activity could contribute to AAA formation, particularly if they resulted in increased enzymatic activity . Increased PEPD activity has been associated with increased collagen production, both in in vitro experiments [21, 47] and in keloid scars . Excess collagen production is observed in AAA tissue , and has been suggested to contribute to weakening of the aneurysm wall . PEPD is also regulated by several mechanisms relevant to AAA pathogenesis. Nitric oxide, which may contribute to AAA formation , upregulates PEPD activity . Similar to other metalloproteases, PEPD activity is sensitive to doxycycline , a tetracycline antibiotic with anti-inflammatory properties that have been studied for their therapeutic potential in AAA [53–56]. Estrogen can regulate PEPD in vitro [57, 58], an interesting observation given that AAA is six times more common in men than women . Finally, increased serum activity of PEPD has been associated with diseases such as asthma , coronary artery disease , and fatty liver disease .
CD22 is a sialic-acid binding protein found on cells of B-cell lineage. It can inhibit signaling through the B-cell receptor , suggesting that impairment of gene function might lead to dysregulation of the immune response and either autoimmune disease or increased inflammation. Supporting this hypothesis is evidence of a role for CD22 in systemic sclerosis; anti-CD22 autoantibodies contribute to systemic sclerosis pathogenesis  and there is evidence of association between a SNP in CD22 and limited cutaneous systemic sclerosis . Systemic sclerosis is characterized by immune infiltration and excessive fibrosis, both of which are observed in AAA subtype known as inflammatory AAA . Given that patients with inflammatory AAA are more likely to have a positive family history , CD22 polymorphisms could contribute to AAA risk. On the other hand, Cd22 knockout mice display a minimal phenotype with no evidence of increased autoimmune disease . It is plausible, however, that polymorphisms in CD22 could modulate the immune response in an inflammatory disease such as AAA through changes in the amount of CD22 protein produced in a cell or an alteration of the gene's function in B-cell signalling.
Exon sequencing of PEPD and CD22 showed that both have polymorphic coding regions. Polymorphisms that did not result in amino acid substitution or changes to the 3'-UTR were not considered further, since their functional effects are difficult to predict. After investigation for predicted functional consequences, all of the sequence changes identified in the coding regions or 3'-UTR of CD22 and PEPD appeared to be tolerated.
One limitation of this study was that the sample size used for genetic association provided only modest power. Although we did observe nominal association in several genes, only one remained significant after correction for multiple testing. Our results should, however, be considered in light of the prior evidence of linkage on chromosome 19q13. While this evidence does indicate the presence of variants contributing to AAA risk at this locus, the differences between linkage and association do not make identification of associated variants a given. Linkage is tolerant of allelic heterogeneity, whereas a variant must be sufficiently common to be detected by association. Therefore, a biologically relevant variant in a linked region may exhibit either weak association, as we observed, or no evidence of association (extensive allelic heterogeneity). Furthermore, if there is also locus heterogeneity in genetic risk factors between populations, increasing sample size using subjects from a different population than that originally studied may actually decrease the evidence of association observed. In light of this and our observation of association at multiple SNPs for each gene, we consider our findings for PEPD and CD22 worth additional studies.
It is possible that the associations seen here resulted from spurious associations or from population stratification. A recent association study examining SNPs from the chromosome 19 linkage interval in the Dutch population found several nominally associated SNPs but none remained significant for multiple testing . Interestingly, the SNP showing the strongest evidence of association resided in CEPBG, which is in agreement with our observation of association in the region of CEBPG and PEPD (Figure 1).
Finally, by focusing on functional candidate genes rather than genotyping the entire linkage region, it is possible that linked and associated genes were overlooked. The strategy presented here was based on reducing the number of tests due to the limited power of our sample and the increased ability to interpret associations in genes of known function. Recent technological improvements in high-throughput sequencing provide a potentially more efficient approach to follow-up of linkage results [66, 67]. Deep sequencing at high coverage of linkage intervals in members of linked families has identified novel loci. For late age-at-onset diseases the lack of complete nuclear pedigrees and inability to identify definitively unaffected individuals, will reduce the approach to affected relative pair sequencing.
In the present study nine functional positional candidate genes on AAA1 locus on chromosome 19 were investigated. Two of the genes, CD22 and PEPD showed modest level of evidence of being involved in AAA pathogenesis. This evidence came from a nominal association of SNPs residing in these genes to AAA, identification of novel sequence changes and expression of these proteins in aneurysmal tissue. If replicated in independent studies, the findings provide important information about AAA pathogenesis.
We thank Dan Lott, Sara McNorton, and Alya'a Sammak at the AGTC at Wayne State University for their work on SNP genotyping, and Dr. Michael Hagen at the AGTC for DNA sequencing. This project was funded in part by the National Heart, Lung, and Blood Institute (HL0643I0 to HK and HL044682 to REF). JHL is a recipient of a Predoctoral Fellowship from the National Institute on Aging, NIH (AG030900), and in 2005-2007 GML was a recipient of a Predoctoral Fellowship from the American Heart Association (0510063Z and 0710099Z). Some of the results of this paper were obtained by using the program package S.A.G.E., which is supported by a U.S. Public Health Service Resource Grant (RR03655) from the National Center for Research Resources.
- Lederle FA, Johnson GR, Wilson SE, Chute EP, Hye RJ, Makaroun MS, Barone GW, Bandyk D, Moneta GL, Makhoul RG: The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators. Arch Intern Med. 2000, 160: 1425-1430. 10.1001/archinte.160.10.1425.View ArticlePubMed
- Keeling WB, Armstrong PA, Stone PA, Bandyk DF, Shames ML: An overview of matrix metalloproteinases in the pathogenesis and treatment of abdominal aortic aneurysms. Vasc Endovascular Surg. 2005, 39: 457-464. 10.1177/153857440503900601.View ArticlePubMed
- Liu J, Sukhova GK, Yang JT, Sun J, Ma L, Ren A, Xu WH, Fu H, Dolganov GM, Hu C, et al: Cathepsin L expression and regulation in human abdominal aortic aneurysm, atherosclerosis, and vascular cells. Atherosclerosis. 2006, 184: 302-311. 10.1016/j.atherosclerosis.2005.05.012.View ArticlePubMed
- Sukhova GK, Shi GP, Simon DI, Chapman HA, Libby P: Expression of the elastolytic cathepsins S and K in human atheroma and regulation of their production in smooth muscle cells. J Clin Invest. 1998, 102: 576-583. 10.1172/JCI181.PubMed CentralView ArticlePubMed
- Chamberlain CM, Ang LS, Boivin WA, Cooper DM, Williams SJ, Zhao H, Hendel A, Folkesson M, Swedenborg J, Allard MF, et al: Perforin-independent extracellular granzyme B activity contributes to abdominal aortic aneurysm. Am J Pathol. 2010, 176: 1038-1049. 10.2353/ajpath.2010.090700.PubMed CentralView ArticlePubMed
- Koch AE, Haines GK, Rizzo RJ, Radosevich JA, Pope RM, Robinson PG, Pearce WH: Human abdominal aortic aneurysms. Immunophenotypic analysis suggesting an immune-mediated response. Am J Pathol. 1990, 137: 1199-1213.PubMed CentralPubMed
- Kuivaniemi H, Platsoucas CD, Tilson MD: Aortic aneurysms: an immune disease with a strong genetic component. Circulation. 2008, 117: 242-252. 10.1161/CIRCULATIONAHA.107.690982.PubMed CentralView ArticlePubMed
- Nischan J, Lenk GM, Boddy AM, Lillvis JH, Tromp G, Kuivaniemi H: Abdominal aortic aneurysms- a complex genetic disease. Aneurysms: Types, Risks, Formation and Treatment. Edited by: Laurent A, Morel E. Hauppage. 2009, NY: Nova Science Publishers, Inc
- Hinterseher I, Tromp G, Kuivaniemi H: Genes and Abdominal Aortic Aneurysm. Ann Vasc Surg. 2010.
- Lillvis JH, Lenk GM, Kuivaniemi H: Genetics of Abdominal Aortic Aneurysms. Aortic Aneurysms: Pathogenesis and Treatment. Edited by: Upchurch G, Criado E. 2008, Totowa, NJ: Humana Press Inc, 1-26.
- Gretarsdottir S, Baas AF, Thorleifsson G, Holm H, den Heijer M, de Vries JP, Kranendonk SE, Zeebregts CJ, van Sterkenburg SM, Geelkerken RH, et al: Genome-wide association study identifies a sequence variant within the DAB2IP gene conferring susceptibility to abdominal aortic aneurysm. Nat Genet. 2010, 42: 692-697. 10.1038/ng.622.PubMed CentralView ArticlePubMed
- Helgadottir A, Thorleifsson G, Magnusson KP, Grétarsdottir S, Steinthorsdottir V, Manolescu A, Jones GT, Rinkel GJ, Blankensteijn JD, Ronkainen A, et al: The same sequence variant on 9p21 associates with myocardial infarction, abdominal aortic aneurysm and intracranial aneurysm. Nat Genet. 2008, 40: 217-224. 10.1038/ng.72.View ArticlePubMed
- Jones GT, Thompson AR, van Bockxmeer FM, Hafez H, Cooper JA, Golledge J, Humphries SE, Norman PE, van Rij AM: Angiotensin II type 1 receptor 1166C polymorphism is associated with abdominal aortic aneurysm in three independent cohorts. Arterioscler Thromb Vasc Biol. 2008, 28: 764-770. 10.1161/ATVBAHA.107.155564.PubMed CentralView ArticlePubMed
- McColgan P, Peck GE, Greenhalgh RM, Sharma P: The genetics of abdominal aortic aneurysms: a comprehensive meta-analysis involving eight candidate genes in over 16,700 patients. Int Surg. 2009, 94: 350-358.PubMed
- Shibamura H, Olson JM, van Vlijmen-Van Keulen C, Buxbaum SG, Dudek DM, Tromp G, Ogata T, Skunca M, Sakalihasan N, Pals G, et al: Genome scan for familial abdominal aortic aneurysm using sex and family history as covariates suggests genetic heterogeneity and identifies linkage to chromosome 19q13. Circulation. 2004, 109: 2103-2108. 10.1161/01.CIR.0000127857.77161.A1.View ArticlePubMed
- van Vlijmen-van Keulen CJ, Rauwerda JA, Pals G: Genome-wide linkage in three Dutch families maps a locus for abdominal aortic aneurysms to chromosome 19q13.3. Eur J Vasc Endovasc Surg. 2005, 30: 29-35. 10.1016/j.ejvs.2004.12.029.View ArticlePubMed
- Olson JM, Vongpunsawad S, Kuivaniemi H, Ronkainen A, Hernesniemi J, Ryynanen M, Kim LL, Tromp G: Search for intracranial aneurysm susceptibility gene(s) using Finnish families. BMC Med Genet. 2002, 3: 7-10.1186/1471-2350-3-7.PubMed CentralView ArticlePubMed
- van der Voet M, Olson JM, Kuivaniemi H, Dudek DM, Skunca M, Ronkainen A, Niemela M, Jaaskelainen J, Hernesniemi J, Helin K, et al: Intracranial aneurysms in Finnish families: confirmation of linkage and refinement of the interval to chromosome 19q13.3. Am J Hum Genet. 2004, 74: 564-571. 10.1086/382285.PubMed CentralView ArticlePubMed
- Yamada S, Utsunomiya M, Inoue K, Nozaki K, Inoue S, Takenaka K, Hashimoto N, Koizumi A: Genome-wide scan for Japanese familial intracranial aneurysms: linkage to several chromosomal regions. Circulation. 2004, 110: 3727-3733. 10.1161/01.CIR.0000143077.23367.18.View ArticlePubMed
- Onouchi Y, Tamari M, Takahashi A, Tsunoda T, Yashiro M, Nakamura Y, Yanagawa H, Wakui K, Fukushima Y, Kawasaki T, Hata A: A genomewide linkage analysis of Kawasaki disease: evidence for linkage to chromosome 12. J Hum Genet. 2007, 52: 179-190. 10.1007/s10038-006-0092-3.View ArticlePubMed
- Surazynski A, Miltyk W, Palka J, Phang JM: Prolidase-dependent regulation of collagen biosynthesis. Amino Acids. 2008, 35: 731-738. 10.1007/s00726-008-0051-8.View ArticlePubMed
- Nitschke L: CD22 and Siglec-G: B-cell inhibitory receptors with distinct functions. Immunol Rev. 2009, 230: 128-143. 10.1111/j.1600-065X.2009.00801.x.View ArticlePubMed
- Hitomi Y, Tsuchiya N, Hasegawa M, Fujimoto M, Takehara K, Tokunaga K, Sato S: Association of CD22 gene polymorphism with susceptibility to limited cutaneous systemic sclerosis. Tissue Antigens. 2007, 69: 242-249. 10.1111/j.1399-0039.2007.00801.x.View ArticlePubMed
- Ogata T, Gregoire L, Goddard KA, Skunca M, Tromp G, Lancaster WD, Parrado AR, Lu Q, Shibamura H, Sakalihasan N, et al: Evidence for association between the HLA-DQA locus and abdominal aortic aneurysms in the Belgian population: a case control study. BMC Med Genet. 2006, 7: 67-10.1186/1471-2350-7-67.PubMed CentralView ArticlePubMed
- Ogata T, Shibamura H, Tromp G, Sinha M, Goddard KA, Sakalihasan N, Limet R, MacKean GL, Arthur C, Sueda T, et al: Genetic analysis of polymorphisms in biologically relevant candidate genes in patients with abdominal aortic aneurysms. J Vasc Surg. 2005, 41: 1036-1042. 10.1016/j.jvs.2005.02.020.PubMed CentralView ArticlePubMed
- Dean FB, Hosono S, Fang L, Wu X, Faruqi AF, Bray-Ward P, Sun Z, Zong Q, Du Y, Du J, et al: Comprehensive human genome amplification using multiple displacement amplification. Proc Natl Acad Sci USA. 2002, 99: 5261-5266. 10.1073/pnas.082089499.PubMed CentralView ArticlePubMed
- Tromp G, Wu Y, Prockop DJ, Madhatheri SL, Kleinert C, Earley JJ, Zhuang J, Norrgard O, Darling RC, Abbott WM, et al: Sequencing of cDNA from 50 unrelated patients reveals that mutations in the triple-helical domain of type III procollagen are an infrequent cause of aortic aneurysms. J Clin Invest. 1993, 91: 2539-2545. 10.1172/JCI116490.PubMed CentralView ArticlePubMed
- Ashburner M, Ball CA, Blake JA, Botstein D, Butler H, Cherry JM, Davis AP, Dolinski K, Dwight SS, Eppig JT, et al: Gene ontology: tool for the unification of biology. The Gene Ontology Consortium. Nat Genet. 2000, 25: 25-29. 10.1038/75556.PubMed CentralView ArticlePubMed
- Kanehisa M, Goto S: KEGG: kyoto encyclopedia of genes and genomes. Nucleic Acids Res. 2000, 28: 27-30. 10.1093/nar/28.1.27.PubMed CentralView ArticlePubMed
- Lenk GM, Tromp G, Weinsheimer S, Gatalica Z, Berguer R, Kuivaniemi H: Whole genome expression profiling reveals a significant role for immune function in human abdominal aortic aneurysms. BMC Genomics. 2007, 8: 237-10.1186/1471-2164-8-237.PubMed CentralView ArticlePubMed
- Purcell S, Cherny SS, Sham PC: Genetic Power Calculator: design of linkage and association genetic mapping studies of complex traits. Bioinformatics. 2003, 19: 149-150. 10.1093/bioinformatics/19.1.149.View ArticlePubMed
- Steemers FJ, Gunderson KL: Illumina, Inc. Pharmacogenomics. 2005, 6: 777-782. 10.2217/146224126.96.36.1997.View ArticlePubMed
- Wigginton JE, Cutler DJ, Abecasis GR: A note on exact tests of Hardy-Weinberg equilibrium. Am J Hum Genet. 2005, 76: 887-893. 10.1086/429864.PubMed CentralView ArticlePubMed
- Barrett JC, Fry B, Maller J, Daly MJ: Haploview: analysis and visualization of LD and haplotype maps. Bioinformatics. 2005, 21: 263-265. 10.1093/bioinformatics/bth457.View ArticlePubMed
- S.A.G.E Statistical Analysis for Genetic Epidemiology. 2009, Cleveland: Department of Epidemiology and Biostatistics, Case Western Reserve University, Release 6.0.1 edition
- Schaid DJ, Rowland CM, Tines DE, Jacobson RM, Poland GA: Score tests for association between traits and haplotypes when linkage phase is ambiguous. Am J Hum Genet. 2002, 70: 425-434. 10.1086/338688.PubMed CentralView ArticlePubMed
- Rozen S, Skaletsky H: Primer3 on the www for general users and for biologist programmers. Methods Mol Biol. 2000, 132: 365-386.PubMed
- Ng PC, Henikoff S: SIFT: Predicting amino acid changes that affect protein function. Nucleic Acids Res. 2003, 31: 3812-3814. 10.1093/nar/gkg509.PubMed CentralView ArticlePubMed
- Blom N, Gammeltoft S, Brunak S: Sequence and structure-based prediction of eukaryotic protein phosphorylation sites. J Mol Biol. 1999, 294: 1351-1362. 10.1006/jmbi.1999.3310.View ArticlePubMed
- Griffiths-Jones S, Grocock RJ, van Dongen S, Bateman A, Enright AJ: miRBase: microRNA sequences, targets and gene nomenclature. Nucleic Acids Res. 2006, 34: D140-144. 10.1093/nar/gkj112.PubMed CentralView ArticlePubMed
- Griffiths-Jones S, Saini HK, van Dongen S, Enright AJ: miRBase: tools for microRNA genomics. Nucleic Acids Res. 2008, 36: D154-158. 10.1093/nar/gkm952.PubMed CentralView ArticlePubMed
- Bartel DP: MicroRNAs: genomics, biogenesis, mechanism, and function. Cell. 2004, 116: 281-297. 10.1016/S0092-8674(04)00045-5.View ArticlePubMed
- Pearce WH, Koch AE: Cellular components and features of immune response in abdominal aortic aneurysms. Ann N Y Acad Sci. 1996, 800: 175-185. 10.1111/j.1749-6632.1996.tb33308.x.View ArticlePubMed
- Stella A, Gargiulo M, Pasquinelli G, Preda P, Faggioli GL, Cenacchi G, D'Addato M: The cellular component in the parietal infiltrate of inflammatory abdominal aortic aneurysms (IAAA). Eur J Vasc Surg. 1991, 5: 65-70. 10.1016/S0950-821X(05)80929-6.View ArticlePubMed
- Walton LJ, Powell JT, Parums DV: Unrestricted usage of immunoglobulin heavy chain genes in B cells infiltrating the wall of atherosclerotic abdominal aortic aneurysms. Atherosclerosis. 1997, 135: 65-71. 10.1016/S0021-9150(97)00152-4.View ArticlePubMed
- Lupi A, Tenni R, Rossi A, Cetta G, Forlino A: Human prolidase and prolidase deficiency: an overview on the characterization of the enzyme involved in proline recycling and on the effects of its mutations. Amino Acids. 2008, 35: 739-752. 10.1007/s00726-008-0055-4.View ArticlePubMed
- Surazynski A, Liu Y, Miltyk W, Phang JM: Nitric oxide regulates prolidase activity by serine/threonine phosphorylation. J Cell Biochem. 2005, 96: 1086-1094. 10.1002/jcb.20631.View ArticlePubMed
- Duong HS, Zhang QZ, Le AD, Kelly AP, Kamdar R, Messadi DV: Elevated prolidase activity in keloids: correlation with type I collagen turnover. Br J Dermatol. 2006, 154: 820-828. 10.1111/j.1365-2133.2006.07167.x.View ArticlePubMed
- Baxter BT, Davis VA, Minion DJ, Wang YP, Lynch TG, McManus BM: Abdominal aortic aneurysms are associated with altered matrix proteins of the nonaneurysmal aortic segments. J Vasc Surg. 1994, 19: 797-802.View ArticlePubMed
- Deguchi JO, Huang H, Libby P, Aikawa E, Whittaker P, Sylvan J, Lee RT, Aikawa M: Genetically engineered resistance for MMP collagenases promotes abdominal aortic aneurysm formation in mice infused with angiotensin II. Lab Invest. 2009, 89: 315-326. 10.1038/labinvest.2008.167.PubMed CentralView ArticlePubMed
- Lizarbe TR, Tarin C, Gomez M, Lavin B, Aracil E, Orte LM, Zaragoza C: Nitric oxide induces the progression of abdominal aortic aneurysms through the matrix metalloproteinase inducer EMMPRIN. Am J Pathol. 2009, 175: 1421-1430. 10.2353/ajpath.2009.080845.PubMed CentralView ArticlePubMed
- Karna E, Palka J, Wolczynski S: Doxycycline-induced inhibition of prolidase activity in human skin fibroblasts and its involvement in impaired collagen biosynthesis. Eur J Pharmacol. 2001, 430: 25-31. 10.1016/S0014-2999(01)01372-3.View ArticlePubMed
- Abdul-Hussien H, Hanemaaijer R, Verheijen JH, van Bockel JH, Geelkerken RH, Lindeman JH: Doxycycline therapy for abdominal aneurysm: Improved proteolytic balance through reduced neutrophil content. J Vasc Surg. 2009, 49: 741-749. 10.1016/j.jvs.2008.09.055.View ArticlePubMed
- Baxter BT, Pearce WH, Waltke EA, Littooy FN, Hallett JW, Kent KC, Upchurch GR, Chaikof EL, Mills JL, Fleckten B, et al: Prolonged administration of doxycycline in patients with small asymptomatic abdominal aortic aneurysms: report of a prospective (Phase II) multicenter study. J Vasc Surg. 2002, 36: 1-12. 10.1067/mva.2002.125018.View ArticlePubMed
- Curci JA, Mao D, Bohner DG, Allen BT, Rubin BG, Reilly JM, Sicard GA, Thompson RW: Preoperative treatment with doxycycline reduces aortic wall expression and activation of matrix metalloproteinases in patients with abdominal aortic aneurysms. J Vasc Surg. 2000, 31: 325-342. 10.1016/S0741-5214(00)90163-0.View ArticlePubMed
- Lindeman JH, Abdul-Hussien H, van Bockel JH, Wolterbeek R, Kleemann R: Clinical trial of doxycycline for matrix metalloproteinase-9 inhibition in patients with an abdominal aneurysm: doxycycline selectively depletes aortic wall neutrophils and cytotoxic T cells. Circulation. 2009, 119: 2209-2216. 10.1161/CIRCULATIONAHA.108.806505.View ArticlePubMed
- Miltyk W, Anchim T, Wolczynski S, Palka J: Estrogen-dependent regulation of prolidase activity in breast cancer MCF-7 cells. Gynecol Endocrinol. 1999, 13: 166-174. 10.3109/09513599909167551.View ArticlePubMed
- Wolczynski S, Surazynski A, Swiatecka J, Palka J: Estrogenic and antiestrogenic effects of raloxifene on collagen metabolism in breast cancer MCF-7 cells. Gynecol Endocrinol. 2001, 15: 225-233.View ArticlePubMed
- Cakmak A, Zeyrek D, Atas A, Celik H, Aksoy N, Erel O: Serum prolidase activity and oxidative status in patients with bronchial asthma. J Clin Lab Anal. 2009, 23: 132-138. 10.1002/jcla.20303.View ArticlePubMed
- Yildiz A, Demirbag R, Yilmaz R, Gur M, Altiparmak IH, Akyol S, Aksoy N, Ocak AR, Erel O: The association of serum prolidase activity with the presence and severity of coronary artery disease. Coron Artery Dis. 2008, 19: 319-325. 10.1097/MCA.0b013e32830042ba.View ArticlePubMed
- Kayadibi H, Gultepe M, Yasar B, Ince AT, Ozcan O, Ipcioglu OM, Kurdas OO, Bolat B, Benek YZ, Guveli H, et al: Diagnostic value of serum prolidase enzyme activity to predict the liver histological lesions in non-alcoholic fatty liver disease: a surrogate marker to distinguish steatohepatitis from simple steatosis. Dig Dis Sci. 2009, 54: 1764-1771. 10.1007/s10620-008-0535-0.View ArticlePubMed
- Odaka M, Hasegawa M, Hamaguchi Y, Ishiura N, Kumada S, Matsushita T, Komura K, Sato S, Takehara K, Fujimoto M: Autoantibody-mediated regulation of B cell responses by functional anti-CD22 autoantibodies in patients with systemic sclerosis. Clin Exp Immunol. 2010, 159: 176-184. 10.1111/j.1365-2249.2009.04059.x.PubMed CentralView ArticlePubMed
- Tang T, Boyle JR, Dixon AK, Varty K: Inflammatory abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2005, 29: 353-362.View ArticlePubMed
- Nitecki SS, Hallett JW, Stanson AW, Ilstrup DM, Bower TC, Cherry KJ, Gloviczki P, Pairolero PC: Inflammatory abdominal aortic aneurysms: a case-control study. J Vasc Surg. 1996, 23: 860-868. 10.1016/S0741-5214(96)70249-5.View ArticlePubMed
- Baas AF, Medic J, van't Slot R, de Vries JP, van Sambeek MR, Geelkerken BH, Boll BP, Grobbee DE, Wijmenga C, Ruigrok YM, Blankensteijn JD: Association Study of Single Nucleotide Polymorphisms on Chromosome 19q13 With Abdominal Aortic Aneurysm. Angiology. 2010, 61: 243-247. 10.1177/0003319709354752.View ArticlePubMed
- Rehman AU, Morell RJ, Belyantseva IA, Khan SY, Boger ET, Shahzad M, Ahmed ZM, Riazuddin S, Khan SN, Friedman TB: Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79. Am J Hum Genet. 2010, 86: 378-388. 10.1016/j.ajhg.2010.01.030.PubMed CentralView ArticlePubMed
- Rosa-Rosa JM, Gracia-Aznarez FJ, Hodges E, Pita G, Rooks M, Xuan Z, Bhattacharjee A, Brizuela L, Silva JM, Hannon GJ, Benitez J: Deep sequencing of target linkage assay-identified regions in familial breast cancer: methods, analysis pipeline and troubleshooting. PLoS One. 2010, 5: e9976-10.1371/journal.pone.0009976.PubMed CentralView ArticlePubMed
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2350/12/14/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.