Contribution of TMC6 and TMC8 (EVER1 and EVER2) variants to cervical cancer susceptibility.

Cervical cancer (CxCa) is caused by persistent human papillomavirus (HPV) infection; genetic predisposition is also suspected to play a role. Our study is a targeted candidate gene follow-up based on: (i) strong clinical evidence demonstrating that mutations in the TMC6 and TMC8 (EVER1 and EVER2) genes associate with the HPV-associated disease epidermodysplasia verruciformis (EV) and (ii) recent epidemiological data suggesting a genetic susceptibility conferred by polymorphisms in such genes for skin and CxCa. Clarifying the association of the TMC6/8 genes with risk of CxCa will help in understanding why some HPV-infected women develop persistent infection, cervical lesions and eventually cancer while others do not. Twenty-two single nucleotide polymorphisms (SNPs) harboring the TMC6/8 genes were genotyped in 2,989 cases with cervical intraepithelial neoplasia grade III or invasive CxCa and 2,281 controls from the Swedish population. Association was evaluated in logistic regression models. Two SNPs displayed association with cervical disease: rs2290907 [odds ratio (OR)(GGvsAA) = 0.6, 95% confidence interval (95% CI): 0.3-0.9, p = 0.02)] and rs16970849 (OR(AGvsGG) = 0.8, 95% CI: 0.66-0.98, p = 0.03). The present data support the involvement of the TMC6/8 region in CxCa susceptibility but further analyses are needed to replicate our findings, fully characterize the region and understand the function of the genetic variants involved.

Evaluation of Fanconi anaemia genes FANCA, FANCC and FANCL in cervical cancer susceptibility.

OBJECTIVE: Disrupting the function of any of the 13 Fanconi anaemia (FA) genes causes a DNA repair deficiency disorder, with patients being susceptible to a number of cancer types. Variation in the family of FA genes has been suggested to affect risk of cervical cancer. The current study evaluates the influence of three genes in the FA pathway on cervical cancer risk in Swedish women. METHODS: TagSNPs in FANCA, FANCC and FANCL were selected using the Tagger algorithm in Haploview. A total of 81 tagSNPs were genotyped in 782 cases (CIN3 or ICC) and 775 controls using the Illumina GoldenGate Assay and statistically analyzed for association with cervical cancer. RESULTS: 72 SNPs were successfully genotyped in >98% of the samples. Nominal associations were detected for FANCA rs11649196 (p=0.05) and rs4128763 in FANCC (p=0.02). The associations did not withstand correction for multiple testing. CONCLUSIONS: The current study does not support that genetic variation in FANCA, FANCC or FANCL genes affects susceptibility to cervical cancer in the Swedish population.

Interaction of immunological genes on chromosome 2q33 and IFNG in susceptibility to cervical cancer.

OBJECTIVE: Cervical cancer is caused by persistent infection with human papillomavirus and genetic susceptibility factors may augment disease risk. The immune response consists of complex interactions and it was recently proposed that the association of combinations of genotypes at several genes should be examined. In support of this the combination CD28+17(TT)/IFNG+874(AA) was shown to increase cervical cancer risk in a Brazilian population (VB Guzman et al. New approach reveals CD28 and IFNG gene interaction in the susceptibility to cervical cancer. Hum Mol Genet 2008;17:1838-44) and our aim was to replicate this finding. METHODS: We re-examined the proposed associations by analysis of polymorphisms at CD28, IFNG, TNF, PDCD1, ICOS and CTLA4 in 1306 Swedish cases and 811 controls. RESULTS: Logistic regression analysis detected association at single SNP level for CD28+17 (p=0.01), IFNG+874 (p=0.02), and PDCD1+7785 (p=0.04). The two locus combination CD28+17(TT)/IFNG+874(AA) (OR=0.76 (0.60-0.96, empirical p=0.03) and the three-locus combination CD28+17(TT)/IFNG+874(AA)/ICOS+1564(TT) (OR=0.65(0.49-0.87), empirical p=0.006) were associated with decreased risk. The strongest association was detected for the combination CTLA4-319 (CC)/IFNG (AA) (OR=0.67(0.53-0.84), empirical p=0.0007). CONCLUSION: The observation that these combinations of loci are associated in different populations supports their importance in cervical cancer development although the opposite directions of the effect call for clarification. The polymorphisms studied might not be the functional variants per se, but linked to those exerting a functional effect. The opposite associations in the two populations could then be explained by differences in linkage disequilibrium and population structure.

Temporal trends over 3 decades and intrafamilial clustering of HPV types in Swedish patients with cervical cancer in situ.

Information on HPV type distribution in cervical cancer in situ in different populations is needed for evaluation of prophylactic vaccination programs targeting HPV 16 and 18. In our study, the HPV type prevalence in 1,079 Swedish women from multicase families diagnosed with cervical cancer in situ 1965-1993 was investigated using real-time PCR and archival tissue material. HPV type information was obtained for 974 samples. Among these, HPV 16 (61%) was the dominant type followed by HPV 33/52/58 (24%), HPV 31 (13%) and HPV 18/45 (12%). The detected prevalence of HPV 16 among cancer in situ decreased by 13% over the study period while the group of low frequency high-risk types increased. Related women were not prone to infection by the same type. These data suggest that the prevalence of individual HPV types has changed over time in Swedish patients with cervical cancer in situ. Large-scale studies of pathology biobank materials will enable further insight into the temporal changes of individual HPV types, as baseline information to properly evaluate the effect of vaccine programs. The findings also indicate that genetic susceptibility to cervical cancer operates through general and not type specific susceptibility to HPV infection.

Polymorphisms in 9q32 and TSCOT are linked to cervical cancer in affected sib-pairs with high mean age at diagnosis.

Cervical cancer is a multifactorial disease influenced by both environmental and genetic factors. We have previously found linkage to 9q32 in a genomewide scan of affected sib-pairs (ASPs) with cervical cancer and to the thymic stromal co-transporter (TSCOT), a candidate gene in this region. Here we examined the contribution of 9q32 and TSCOT to cervical cancer susceptibility using at larger material of 641 ASPs, 278 of which were included in the earlier genome-scan. Since heritable forms of cancer frequently show stronger genetic effects in families with early onset of disease, we stratified the ASPs into two groups based on mean age at diagnosis (MAAD) within sib-pairs. Surprisingly, ASPs with high MAAD (30.5-47.5 years) showed increased sharing at all microsatellite markers at 9q31.1-33.1 and linkage signals of up to MLS = 2.74 for TSCOT SNPs, while ASPs with low MAAD (19-30 years) showed no deviation from random genetic sharing (MLS = 0.00). The difference in allelic sharing between the two MAAD strata was significant (P < 0.005) and is not likely to be explained by the HLA haplotype, a previously known genetic susceptibility factor for cervical cancer. Our results indicate locus heterogeneity in the susceptibility to cervical cancer between the two strata, with polymorphisms in the 9q32 region mainly showing an effect in women with high MAAD.

Variants of chemokine receptor 2 and interleukin 4 receptor, but not interleukin 10 or Fas ligand, increase risk of cervical cancer.

Cervical cancer is caused by persistent infection of oncogenic human papillomavirus (HPV). Most infected women clear the virus without developing cervical lesions and it is likely that immunological host factors affect susceptibility to cervical cancer. The impact of the human leukocyte antigen (HLA) locus on the risk of cervical cancer is established and several other genes involved in immunological pathways have been suggested as biologically plausible candidates. The aim of this study was to examine the potential role of polymorphisms in 4 candidate genes by analysis of 1,306 familial cervical cancer cases and 288 controls. The following genes and polymorphisms were studied: Chemokine receptor 2 (CCR-2) V64I; Interleukin 4 receptor alpha (IL-4R) I75V, S503P and Q576R; Interleukin 10 (IL-10) -592; and Fas ligand (FasL) -844. The CCR-2 64I variant was associated with decreased risk of cervical cancer; homozygote carriers of the 64I variant had an odds ratio of 0.31 (0.12-0.77). This association was detected in both carriers and noncarriers of the HLA DQB1*0602 cervical cancer risk allele. The IL-4R 75V variant was associated with increased risk of cervical tumors, cases homozygote for 75V had an odds ratio of 1.91 (1.27-2.86) with a tendency that the association was stronger in noncarriers of the DQB1*0602 allele. We did not find any association for IL-10 -592, or FasL -844, previously reported to be associated with cervical cancer in the Dutch and Chinese populations, respectively.

Prevalence of the most common high-risk HPV genotypes among women in three new independent states of the former Soviet Union.

Type distribution of HPV has been studied in different geographic regions, but the data are scanty from the new independent states of the former Soviet Union. Here the HPV prevalence and distribution of the most frequent high-risk HPV types among 3,187 women at different risk for HPV and cervical intraepithelial neoplasia in Russia, Belarus, and Latvia is reported. HPV detection, type distribution and viral load analysis in DNA samples from cervical scrapes were done with real-time PCR-based assay detecting HPV types 16, 18, 31, 33, 35, 39, 45, 52, and 58. The overall HPV prevalence was 31.2%, HPV16 was the most prevalent type followed by HPV31 and HPV33 group. The overall HPV prevalences in Russia, Belarus and Latvia were 33.4%, 27.5%, and 26.2%. The type distributions were similar in these countries, except for Latvia where HPV39 was the third prevalent genotype. HPV prevalence was highest (40.8%) among women from sexually transmitted disease clinic, followed by 30.9% among gynecological outpatients and 27.2% in screening patients. HPV detection increased with cytological abnormality (P = 0.0001) and lesion grade in the biopsy (P = 0.0001), from 27% to 72% in normal samples to cancer, and from 64% to 77% in cervical intraepithelial neoplasia 1 to cancer. The normalized viral loads varied greatly between and among different HPV-types. The mean log HPV33 group copies/cell increased from negative for intraepithelial lesions to cancer (P = 0.049). Distribution of the most common high-risk HPV-types seems to be similar in these countries as reported in other major geographical regions.

Type-specific persistence of high-risk human papillomavirus infections in the New Independent States of the former Soviet Union Cohort Study.

BACKGROUND: Prospective follow-up studies have recently suggested that persistent high-risk human papillomavirus (HPV) infections play a key role in the progression of CIN lesions and in the development of cervical cancer. However, data on type-specific persistence, viral integration, and the role of multiple infections are scanty. MATERIALS AND METHODS: A cross-sectional/cohort study was conducted between 1998 and 2002 in three New Independent States of the former Soviet Union comprising a cohort of 3,187 women, of whom 854 women were followed up for a mean of 17 months (SD, 11.6). HPV genotyping was done with real-time PCR, detecting HPV types 16, 18/45, 31, 33/52/58, 35, and 39. The integration status of HPV16 was examined by using a novel Taqman-based PCR method. RESULTS: The mean clearance time for the individual high- risk-type infection was 16.5 months (range = 0.9-34.9 months). HPV16 and HPV31 were the most persistent infections (clearance times = 18.1 and 16.2 months, respectively), whereas HPV39 infections cleared most rapidly. The mean copies per cell in HPV18/45, HPV31, HPV33/52/58, and HPV39 infections were higher in persisting HPV infections than in HPV infections that cleared, but the difference was not significant. Integration of HPV16 was not found to correlate with HPV persistence. CONCLUSIONS: A large proportion of women remained high-risk HPV positive after 18 months. Coinfection with multiple HPV types, viral load, or integration status did not correlate with persistence of high-risk HPV infections.

Identification of susceptibility loci for cervical carcinoma by genome scan of affected sib-pairs.

Cervical cancer is caused by a combination of environmental and genetic risk factors. Infection by oncogenic types of human papillomavirus is recognized as the major environmental risk factor and epidemiological studies indicate that host genetic factors predispose to disease development. A number of genetic susceptibility factors have been proposed, but with exception of the human leukocyte antigen CHLA, class II, have not shown consistent results among studies. We have performed the first genomewide linkage scan using 278 affected sib-pairs to identify loci involved in susceptibility to cervical cancer. A two-step qualitative non-parametric linkage analysis using 387 microsatellites with an average spacing of 10.5 cM revealed excess allelic sharing at nine regions on eight chromosomes. These regions were further analysed with 125 markers to increase the map density to 1.28 cM. Nominal significant linkage was found for three of the nine loci [9q32 (maximum lod-score, MLS) =1.95, P<0.002), 12q24 (MLS=1.25, P<0.015) and 16q24 (MLS=1.35, P<0.012)]. These three regions have previously been connected to human cancers that share characteristics with cervical carcinoma, such as esophageal cancer and Hodgkin's lymphoma. A number of candidate genes involved in defence against viral infections, immune response and tumour suppression are found in these regions. One such gene is the thymic stromal co-transporter (TSCOT). Analyses of TSCOT single nucleotide polymorphisms further strengthen the linkage to this region (MLS=2.40, P<0.001). We propose that the 9q32 region contains susceptibility locus for cervical cancer and that TSCOT is a candidate gene potentially involved in the genetic predisposition to this disease.

Reduced incidence of cervical cancer in mothers of sons with allergic rhinoconjunctivitis, asthma or eczema.

Because infection with human papillomavirus is a necessary cause of cervical cancer, it is likely that host immunological factors involved in defense against such infections are important for susceptibility to this cancer. By examining associations between allergy in sons and cervical cancer in their mothers, we aimed to test for genetic components involved in both allergy and cervical cancer development. Women born in Sweden between 1932 and 1960 with at least 1 son with medical records from military conscription examination were included in the study (N = 717,963). Among these women there were 41,910 in situ and 3,618 invasive cases of cervical cancer. Hazard ratios of in situ and invasive cervical cancer were estimated as functions of allergic rhinoconjunctivitis, asthma and eczema diagnoses in sons. Adjustment was made for the possible confounders: age, year of birth, education, socio-economic index, geography, number of conscripted sons and total number of offspring. The risk of in situ and invasive cervical cancer was lower for women having sons diagnosed with hypersensitivity (allergic rhinoconjunctivitis, asthma or eczema). Fully adjusted hazard ratios for women with 1 hypersensitive son were for in situ 0.86 (95% CI 0.84-0.88) and for invasive cervical cancer 0.82 (95% CI 0.74-0.91). The protective effects were similar between the 3 allergic diagnoses and increased with number of sons with a diagnosis. There was no significant association between non-cervical cancer in mothers and allergy in sons. These results strengthen the hypothesis that inherited immunological factors are important in determining risk of cervical cancer, probably by affecting mechanisms for viral persistence.

Height at age 18 years is a strong predictor of attained education later in life: cohort study of over 950,000 Swedish men.

BACKGROUND: Adult body height has been related to socioeconomic position in cross-sectional studies. Intelligence, shared family factors, and non-familial circumstances may contribute to associations between height and attained education, but their relative importance has been difficult to resolve. METHODS: A nation-wide record-linkage cohort study of over 950 000 Swedish men born 1950-75 followed with respect to attained education for up to 27 years after measurement of height at age 18 (baseline). The association between height and attained education in later life was investigated by logistic regression modelling with adjustment for age, geography, parental socioeconomic position, and cognitive ability. Shared family factors were accounted for in analyses of full-brother-pairs using conditional logistic regression. RESULTS: The odds ratio (OR) for attaining higher education 7-27 years after baseline was 1.10 [95% confidence interval (95% CI) 1.09-1.10] in fully adjusted models per 5 cm increase in height. Men taller than 194 cm were two to three times more likely to obtain a higher education as compared with men shorter than 165 cm. The association remained within brother-pairs, OR 1.08 (95% CI 1.07-1.10), suggesting that non-familial factors contribute to the association between height and education attainment. A significant interaction (P < 0.0001) was found between year of birth, height, and attained education, showing slightly weaker associations among later birth cohorts. CONCLUSIONS: The strong positive association between height and educational achievement remaining after adjustment for year of birth, parental socioeconomic position, other shared family factors, and cognitive ability may reflect educational discrimination based on height although residual confounding cannot be ruled out.

Interaction of host and viral risk factors for development of cervical carcinoma in situ.

Infection by oncogenic human papillomavirus (HPV) is a necessary but not sufficient cause of cervical carcinoma. Several host genetic and viral factors have been reported to increase the risk of carcinoma development given an HPV infection. In our study, we have analysed the contribution of HPV 16 E6 sequence subtype and allelic variation at human leukocyte antigen (HLA) class II loci to the risk of developing cervical carcinoma in situ. Non-European-like HPV 16 E6 sequence subtypes were not found to be associated with an increased risk of cervical carcinoma, as compared to European-like variants. However, an association was found between the HPV 16 E6 L83V variant and the DR*04-DQ*03 haplotype. This association has been observed in several independent studies and shows that both the host HLA class II genotype and viral subtype will affect the risk of an infection progressing into cervical carcinoma.

HLA class II allele control of HPV load in carcinoma in situ of the cervix uteri.

Human papillomavirus (HPV) infection is the most important risk factor for development of cervical carcinoma. Carriers of certain HLA class II alleles, e.g., DRB1*1501 and DQB1*0602, are more prone to HPV 16 infection and cervical carcinoma, whereas other alleles, e.g., DRB1*1301 and DQB1*0603, render carriers less susceptible to the disease. In our study comprising 484 cases and 601 controls, we examine the effect of HLA class II alleles on viral load of the oncogenic types HPV 18/45 and HPV 31 and risk of developing cervical carcinoma in situ. We find that carriers of the commonly reported protective DRB1*1301 and DQB1*0603 alleles have lower HPV 18/45 load compared to noncarriers and a lower risk of developing HPV 18/45-positive cervical carcinoma. This provides further evidence that the HLA class II-mediated immune response to HPV is important for controlling viral load and outcome of an infection.

A regulatory polymorphism in PDCD1 is associated with susceptibility to systemic lupus erythematosus in humans.

Systemic lupus erythematosus (SLE, OMIM 152700) is a complex autoimmune disease that affects 0.05% of the Western population, predominantly women. A number of susceptibility loci for SLE have been suggested in different populations, but the nature of the susceptibility genes and mutations is yet to be identified. We previously reported a susceptibility locus (SLEB2) for Nordic multi-case families. Within this locus, the programmed cell death 1 gene (PDCD1, also called PD-1) was considered the strongest candidate for association with the disease. Here, we analyzed 2,510 individuals, including members of five independent sets of families as well as unrelated individuals affected with SLE, for single-nucleotide polymorphisms (SNPs) that we identified in PDCD1. We show that one intronic SNP in PDCD1 is associated with development of SLE in Europeans (found in 12% of affected individuals versus 5% of controls; P = 0.00001, r.r. (relative risk) = 2.6) and Mexicans (found in 7% of affected individuals versus 2% of controls; P = 0.0009, r.r. = 3.5). The associated allele of this SNP alters a binding site for the runt-related transcription factor 1 (RUNX1, also called AML1) located in an intronic enhancer, suggesting a mechanism through which it can contribute to the development of SLE in humans.

Host genetic control of HPV 16 titer in carcinoma in situ of the cervix uteri.

Cervical cancer is strongly associated with infection by oncogenic forms of human papillomavirus (HPV). Although most women are able to clear an HPV infection, some develop persistent infections that may lead to cancer. The determinants of persistent infection are largely unknown. We have previously shown that women developing carcinoma in situ of the cervix uteri have higher titers of HPV 16 long before development of cervical neoplasia, indicating that the immune response to HPV is important in determining the outcome of an infection. The HLA class II alleles DRB1*1501 and DQB1*0602 have previously been associated with an increased risk of HPV infection, and carriers of these alleles also tend to have more long-term infections. Together these results indicate that certain HLA alleles may affect the ability to control the HPV copy number. To evaluate this possibility, we studied the HLA class II DRB1*1501-DQB1*0602 haplotype, as well as the alleles individually, and the HPV 16 titer in 928 women from a retrospective case-control study (441 cases and 487 controls). Carriers of the haplotype DRB1*1501-DQB1*0602 allele have a significantly higher HPV 16 titer compared to noncarriers (t-test with unequal variance, p = 0.017). An association was found between the HLA haplotype carrier frequency and HPV 16 titer (Mantel-Haenszel statistics p = 0.005). To study whether titer is related to the persistency of infection, women were divided into groups with long-term and short-term infection. A strong correlation is seen between long-term infection and high viral load and between short-term infection and low viral load. These results show that host genetic factors, e.g., variation at the HLA class II loci studied, may affect the immune reaction to the virus and thereby indirectly increase the susceptibility to carcinoma in situ of the cervix uteri.