| 61. |
- Chatterjee, Koushik, et al.
(författare)
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A Fas Gene Polymorphism Influences Herpes Simplex Virus Type 2 Infection in South African Women
- 2010
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Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 82:12, s. 2082-2086
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Tidskriftsartikel (refereegranskat)abstract
- Herpes simplex virus type 2 (HSV-2) is a common sexually transmitted infection (STI) worldwide that causes genital infection. Among several factors responsible, host genetic factors may play an important role in susceptibility to HSV-2 infection. Apoptosis is a vital mechanism in eliminating virus-infected cells and controlling viral infections. Apoptosis can be regulated and triggered by the interaction between Fas and Fas Ligand (FasL). Polymorphisms in genes encoding Fas and FasL might result in altered apoptosis and contribute in susceptibility to viral infections. Two polymorphisms in Fas gene (FasR-1377G > A, FasR-670A > G) and one in FasL gene (FasL-844T > C) have been well studied and associated with different diseases. These polymorphisms were investigated in 407 South African women of black African and mixed-ancestry origin to determine if they were associated with HSV-2 seropositivity. Two hundred sixty-five women were HSV-2 infected and 142 were non-infected. HSV-2 was detected using HerpeSelect ELISA test and genotyping was performed using TaqMan assay. FasR-1377A allele showed a statistically significant association (P = 0.008) with reduced risk of HSV-2 infection. Analyzing the FasR haplotypes also showed a statistically significant association (P = 0.0001) with FasR-1377/FasR-670 AG haplotype and reduced risk of HSV-2 infection. There was no significant association found with FasR-670A > G and FasL-844T > C polymorphisms and risk of HSV-2 infection. This is, to our knowledge, the first time a non-HLA genetic link with HSV-2 infection has been reported.
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| 62. |
- Chatterjee, Koushik, et al.
(författare)
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Fas and FasL gene polymorphisms are not associated with cervical cancer but differ among Black and Mixed-ancestry South Africans
- 2009
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Ingår i: BMC research notes. - : Springer Science and Business Media LLC. - 1756-0500. ; 2, s. 238-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cervical cancer is one of the most important cancers in African women. Polymorphisms in the Fas (FasR) and Fas ligand (FasL) genes have been reported to be associated with cervical cancer in certain populations. This study investigated whether these polymorphisms are associated with cervical cancer or human papillomavirus (HPV) infection in South African women. FINDINGS: Participants were 447 women with invasive cervical cancer (106 black African and 341 women of mixed-ancestry) and 424 healthy women controls, matched by age, (101 black African and 323 women of mixed-ancestry) and domicile (rural or urban). Two polymorphisms in Fas gene (FasR-1377G/A, FasR-670A/G) and one in FasL gene (FasL844T/C) were genotyped by TaqMan. None of the polymorphisms, or the Fas haplotypes, showed a significant association with cervical cancer. There was also no association with HPV infection in the control group. However, on analysis of the control group, highly significant allele, genotype and haplotype differences were found between the two ethnic groups. There were generally low frequencies of FasR-1377A alleles, FasR-670A alleles and FasL-844C alleles in black women compared to the women of mixed-ancestry. CONCLUSION: This is the first study on the role of Fas and FasL polymorphisms in cervical cancer in African populations. Our results suggest that these SNPs are not associated with cervical cancer in these populations. The allele frequencies of the three SNPs differed markedly between the indigenous African black and mixed-ancestry populations.
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| 63. |
- Chen, Dan, et al.
(författare)
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A cis-eQTL of HLA-DRB1 and a frameshift mutation of MICA contribute to the pattern of association of HLA alleles with cervical cancer
- 2014
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Ingår i: Cancer Medicine. - : Wiley. - 2045-7634. ; 3:2, s. 445-452
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Tidskriftsartikel (refereegranskat)abstract
- The association of classic human leukocyte antigen (HLA) alleles with risk of cervical cancer has been extensively studied, and a protective effect has consistently been found for DRB1*1301, DQA1*0103, and/or DQB1*0603 (these three alleles are in perfect linkage disequilibrium [LD] and often occur on the same haplotype in Europeans), while reports have differed widely with respect to the effect of HLA-B*07, DRB1*1501, and/or DQB1*0602 (the last two alleles are also in perfect LD in Europeans). It is not clear whether the reported HLA alleles are responsible for the differences in cervical cancer susceptibility, or if functional variants at other locations within the major histocompatibility complex (MHC) region may explain the effect. In order to assess the relative contribution of both classic HLA alleles and single-nucleotide polymorphisms (SNPs) within the MHC region to cervical cancer susceptibility, we have imputed classic HLA alleles in 1034 cervical cancer patients and 3948 controls in a Swedish population for an integrated analysis. We found that the protective haplotype DRB1*1301-DQA1*0103-DQB1*0603 has a direct effect on cervical cancer and always occurs together with the C allele of a HLA-DRB1 cis-eQTL (rs9272143), which increases the expression of HLA-DRB1. The haplotype rs9272143C-DRB1*1301-DQA1*0103-DQB1*0603 conferred the strongest protection against cervical cancer (odds ratio [OR] = 0.41, 95% confidence interval [CI] = 0.32-0.52, P = 6.2 × 10(-13)). On the other hand, the associations with HLA-B*0702 and DRB1*1501-DQB1*0602 are attributable to the joint effects of both the HLA-DRB1 cis-eQTL (rs9272143) and a frameshift mutation (G inserion of rs67841474, also known as A5.1) of the MHC class I polypeptide-related sequence A gene (MICA). Variation in LD between the classic HLA loci, rs9272143 and rs67841474 between populations may explain the different associations of HLA-B*07 and DRB1*1501-DQB1*0602 with cervical cancer between studies. The mechanism suggested may also explain similar inconsistent results for other HLA-associated diseases.
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| 64. |
- Chen, Dan, et al.
(författare)
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A systematic investigation of the contribution of genetic variation within the MHC region to HPV seropositivity
- 2015
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 24:9, s. 2681-2688
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Tidskriftsartikel (refereegranskat)abstract
- High-risk mucosal types of human papillomavirus (HPV) cause anogenital and oropharyngeal cancers, whereas cutaneous types (e.g. HPV8 and 77) are suspected to be involved in non-melanoma skin cancer. The antibody response to HPVs is a key determinant of protective immunity, but not all infected individuals seroconvert. Genetic variability of the host may have large impact on seroconversion. A previous genome-wide association study (GWAS) has identified a susceptibility locus (rs41270488) for HPV8 seropositivity within the major histocompatibility complex (MHC) region. To further study this locus, we imputed alleles at classical leukocyte antigen (HLA) loci using HLA*IMP:02 with a reference panel from the HapMap Project and the 1958 Birth Cohort, and conducted an integrated analysis among 4811 central European subjects to assess the contribution of classical HLA alleles and gene copy number variation (CNV) at the hypervariable DRB locus within the MHC region to HPV seropositivity at both the individual HPV type level and the phylogenetic species level. Our study provides evidence that the association noted between rs41270488 and HPV8 seropositivity is driven by two independent variants, namely DQB1*0301 [odds ratio (OR) = 1.51, 95% confidence interval (CI) = 1.36-1.68, P = 1.0 x 10(-14)] and DRB1*1101 (OR = 1.89, 95% CI = 1.57-2.28, P = 1.5 x 10(-11)) within the HLA class II region. Additionally, we identified two correlated alleles DRB1*0701 (OR = 1.67, 95% CI = 1.41-1.98, P = 2.6 x 10(-9)) and DQA1*0201 (OR = 1.67, 95% CI = 1.38-1.93, P = 1.7 x 10(-8)), to be associated with HPV77 seropositivity. Comparable results were observed through imputation using SNP2HLA with another reference panel from the Type 1 diabetes Genetics Consortium. This study provides support for an important role of HLA class II alleles in antibody response to HPV infection.
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| 65. |
- Chen, Dan, et al.
(författare)
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A variant upstream of HLA-DRB1 and multiple variants in MICA influence susceptibility to cervical cancer in a Swedish population
- 2014
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Ingår i: Cancer Medicine. - : John Wiley & Sons. - 2045-7634. ; 3:1, s. 190-198
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Tidskriftsartikel (refereegranskat)abstract
- In a genome-wide association study, we have previously identified and performed the initial replication of three novel susceptibility loci for cervical cancer: rs9272143 upstream of HLA-DRB1, rs2516448 adjacent to MHC class I polypeptide-related sequence A gene (MICA), and rs3117027 at HLA-DPB2. The risk allele T of rs2516448 is in perfect linkage disequilibrium with a frameshift mutation (A5.1) in MICA exon 5, which results in a truncated protein. To validate these associations in an independent study and extend our prior work to MICA exon 5, we genotyped the single-nucleotide polymorphisms at rs9272143, rs2516448, rs3117027 and the MICA exon 5 microsatellite in a nested case–control study of 961 cervical cancer patients (827 carcinoma in situ and 134 invasive carcinoma) and 1725 controls from northern Sweden. The C allele of rs9272143 conferred protection against cervical cancer (odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.65–0.82; P = 1.6 × 10−7), which is associated with higher expression level of HLA-DRB1, whereas the T allele of rs2516448 increased the susceptibility to cervical cancer (OR = 1.33, 95% CI = 1.19–1.49; P = 5.8 × 10−7), with the same association shown with MICA-A5.1. The direction and the magnitude of these associations were consistent with our previous findings. We also identified protective effects of the MICA-A4 (OR = 0.80, 95% CI = 0.68–0.94; P = 6.7 × 10−3) and MICA-A5 (OR = 0.60, 95% CI = 0.50–0.72; P = 3.0 × 10−8) alleles. The associations with these variants are unlikely to be driven by the nearby human leukocyte antigen (HLA) alleles. No association was observed between rs3117027 and risk of cervical cancer. Our results support the role of HLA-DRB1 and MICA in the pathogenesis of cervical cancer.
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| 66. |
- Chen, Dan, et al.
(författare)
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Analysis of the genetic architecture of susceptibility to cervical cancer indicates that common SNPs explain a large proportion of the heritability
- 2015
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 36:9, s. 992-998
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Tidskriftsartikel (refereegranskat)abstract
- The genetic architecture of susceptibility to cervical cancer is not well-understood. By using a genome-wide association study (GWAS) of 1034 cervical cancer patients and 3948 controls with 632 668 single-nucleotide polymorphisms (SNPs), we estimated that 24.0% [standard error (SE) = 5.9%, P = 3.19 x 10(-6)] of variation in liability to cervical cancer is captured by autosomal SNPs, a bit lower than the heritability estimated from family study (27.0%), suggesting that a substantial proportion of the heritability is tagged by common SNPs. The remaining missing heritability most probably reflects incomplete linkage disequilibrium between causal variants and the genotyped SNPs. The variance explained by each chromosome is not related to its length (R-2 = 0.020, P = 0.516). Published genome-wide significant variants only explain 2.1% (SE = 1.5%, P = 0) of phenotypic variance, which reveals that most of the heritability has not been detected, presumably due to small individual effects. Another 2.1% (SE = 1.1%, P = 0.013) of variation is attributable to biological pathways associated with risk of cervical cancer, supporting that pathway analysis can identify part of the hidden heritability. Except for human leukocyte antigen genes and MHC class I polypeptide-related sequence A (MICA), none of the 82 candidate genes/regions reported in other association studies contributes to the heritability of cervical cancer in our dataset. This study shows that risk of cervical cancer is influenced by many common germline genetic variants of small effects. The findings are important for further study design to identify the hiding heritability that has not yet been revealed. More susceptibility loci are yet to be found in GWASs with higher power.
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| 67. |
- Chen, Dan, et al.
(författare)
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Genome-wide Association Study of Susceptibility Loci for Cervical Cancer
- 2013
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 105:9, s. 624-633
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Tidskriftsartikel (refereegranskat)abstract
- Background Cervical carcinoma has a heritable genetic component, but the genetic basis of cervical cancer is still not well understood. Methods We performed a genome-wide association study of 731 422 single nucleotide polymorphisms (SNPs) in 1075 cervical cancer case subjects and 4014 control subjects and replicated it in 1140 case subjects and 1058 control subjects. The association between top SNPs and cervical cancer was estimated by odds ratios (ORs) and 95% confidence intervals (CIs) with unconditional logistic regression. All statistical tests were two-sided. Results Three independent loci in the major histocompatibility complex (MHC) region at 6p21.3 were associated with cervical cancer: the first is adjacent to the MHC class I polypeptide-related sequence A gene (MICA) (rs2516448; OR = 1.42, 95% CI = 1.31 to 1.54; P = 1.6 x 10(-18)); the second is between HLA-DRB1 and HLA-DQA1 (rs9272143; OR = 0.67, 95% CI = 0.62 to 0.72; P = 9.3 x 10(-24)); and the third is at HLA-DPB2 (rs3117027; OR=1.25, 95% CI = 1.15 to 1.35; P = 4.9 x 10(-8)). We also confirmed previously reported associations of B*0702 and DRB1*1501-DQB1*0602 with susceptibility to and DRB1*1301-DQA1*0103-DQB1*0603 with protection against cervical cancer. The three new loci are statistically independent of these specific human leukocyte antigen alleles/haplotypes. MICA encodes a membrane-bound protein that acts as a ligand for NKG2D to activate antitumor effects. The risk allele of rs2516448 is in perfect linkage disequilibrium with a frameshift mutation (A5.1) of MICA, which results in a truncated protein. Functional analysis shows that women carrying this mutation have lower levels of membrane-bound MICA. Conclusions Three novel loci in the MHC may affect susceptibility to cervical cancer in situ, including the MICA-A5.1 allele that may cause impaired immune activation and increased risk of tumor development.
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| 68. |
- Chen, Dan, et al.
(författare)
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Lessons and implications from association studies and post-GWAS analyses of cervical cancer
- 2015
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Ingår i: Trends in Genetics. - : Elsevier BV. - 0168-9525 .- 1362-4555. ; 31:1, s. 41-54
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Forskningsöversikt (refereegranskat)abstract
- Cervical cancer has a heritable genetic component. A large number of genetic associations with cervical cancer have been reported in hypothesis-driven candidate gene studies, but many of these results are either inconsistent or have failed to be independently replicated. Genome-wide association studies (GWAS) have identified additional susceptibility loci previously not implicated in cervical cancer development, highlighting the power of genome-wide unbiased association analyses. Post-GWAS analyses including pathway-based analysis and functional characterization of associated variants have provided new insights into the pathogenesis of cervical cancer. In this review we summarize findings from candidate gene association studies, GWAS, and post-GWAS analyses of cervical cancer. We also discuss gaps in our understanding, possible clinical implications of the findings, and lessons for studies of other complex diseases.
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| 69. |
- Chen, Dan, et al.
(författare)
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MICA polymorphism : biology and importance in cancer
- 2014
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 35:12, s. 2633-2642
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Forskningsöversikt (refereegranskat)abstract
- The major histocompatibility complex class I polypeptide-related sequence A gene (MICA) encodes a membrane-bound protein acting as a ligand to stimulate an activating receptor, NKG2D, expressed on the surface of essentially all human natural killer (NK), γδ T and CD8(+) αβ T cells. MICA protein is absent from most cells but can be induced by infections and oncogenic transformation and is frequently expressed in epithelial tumors. Upon binding to MICA, NKG2D activates cytolytic responses of NK and γδ T cells against infected and tumor cells expressing MICA. Therefore, membrane-bound MICA acts as a signal during the early immune response against infection or spontaneously arising tumors. On the other hand, human tumor cells spontaneously release a soluble form of MICA, causing the downregulation of NKG2D and in turn severe impairment of the antitumor immune response of NK and CD8(+) T cells. This is considered to promote tumor immune evasion and also to compromise host resistance to infections. MICA is the most polymorphic non-classical class I gene. A possible association of MICA polymorphism with genetic predisposition to different cancer types has been investigated in candidate gene-based studies. Two genome-wide association studies have identified loci in MICA that influence susceptibility to cervical neoplasia and hepatitis C virus-induced hepatocellular carcinoma, respectively. Given the current level of interest in the field of MICA gene, we discuss the genetics and biology of the MICA gene and the role of its polymorphism in cancer. Gaps in our understanding and future research needs are also discussed.
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| 70. |
- Chen, Dan, et al.
(författare)
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Pathway analysis of cervical cancer genome-wide association study highlights the MHC region and pathways involved in response to infection
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:22, s. 6047-6060
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Tidskriftsartikel (refereegranskat)abstract
- Cervical cancer is caused by infection with human papillomavirus (HPV). A genome-wide association study (GWAS) has identified several susceptibility loci for cervical cancer, but they explain only a small fraction of cervical cancer heritability. Other variants with weaker effect may be missed due to the stringent significance threshold. To identify important pathways in cervical carcinogenesis, we performed a two-stage pathway analysis in two independent GWASs in the Swedish population, using the single-nucleotide polymorphism (SNP) ratio test. The 565 predefined pathways from Kyoto Encyclopedia of Genes and Genomes and BioCarta databases were systematically evaluated in the discovery stage (1034 cases and 3948 controls with 632 668 SNPs) and the suggestive pathways were further validated in the replication stage (616 cases and 506 controls with 341 358 SNPs). We found 12 pathways that were significant in both stages, and these were further validated using set-based analysis. For 10 of these pathways, the effect was mainly due to genetic variation within the major histocompatibility complex (MHC) region. In addition, we identified a set of novel candidate genes outside the MHC region in the pathways denoted ‘Staphylococcus aureus infection’ and ‘herpes simplex infection’ that influenced susceptibility to cervical cancer (empirical P = 4.99 × 10−5 and 4.99 × 10−5 in the discovery study; empirical P = 8.98 × 10−5 and 0.009 in the replication study, respectively). Staphylococcus aureus infection may evoke an inflammatory response that inadvertently enhances malignant progression caused by HPV infection, and Herpes simplex virus-2 infection may act in conjunction with HPV infection to increase the risk of cervical carcinoma development. These findings provide new insights into the etiology of cervical cancer.
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