Camilla Furu Skjelbred

Polymorphisms of the XRCC1, XRCC3 and XPD genes and risk of colorectal adenoma and carcinoma, in a Norwegian cohort: a case control study

BackgroundGenetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of developing cancer. For colorectal cancer the importance of mutations in mismatch repair genes has been extensively documented. Less is known about other DNA repair pathways in colorectal carcinogenesis. In this study we have focused on the XRCC1, XRCC3 and XPD genes, involved in base excision repair, homologous recombinational repair and nucleotide excision repair, respectively.MethodsWe used a case-control study design (157 carcinomas, 983 adenomas and 399 controls) to test the association between five polymorphisms in these DNA repair genes (XRCC1 Arg194Trp, Arg280His, Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln), and risk of colorectal adenomas and carcinomas in a Norwegian cohort. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression model adjusting for age, gender, cigarette smoking and alcohol consumption.ResultsThe XRCC1 280His allele was associated with an increased risk of adenomas (OR 2.30, 95% CI 1.19–4.46). The XRCC1 399Gln allele was associated with a reduction of risk of high-risk adenomas (OR 0.62, 95% CI 0.41–0.96). Carriers of the variant XPD 751Gln allele had an increased risk of low-risk adenomas (OR 1.40, 95% CI 1.03–1.89), while no association was found with risk of carcinomas.ConclusionOur results suggest an increased risk for advanced colorectal neoplasia in individuals with the XRCC1 Arg280His polymorphism and a reduced risk associated with the XRCC1 Arg399Gln polymorphism. Interestingly, individuals with the XPD Lys751Gln polymorphism had an increased risk of low-risk adenomas. This may suggest a role in regression of adenomas.

The ratio of Matriptase/HAI-1 mRNA is higher in colorectal cancer adenomas and carcinomas than corresponding tissue from control individuals

BackgroundIt has recently been shown that overexpression of the serine protease, matriptase, in transgenic mice causes a dramatically increased frequency of carcinoma formation. Overexpression of HAI-1 and matriptase together changed the frequency of carcinoma formation to normal. This suggests that the ratio of matriptase to HAI-1 influences the malignant progression. The aim of this study has been to determine the ratio of matriptase to HAI-1 mRNA expression in affected and normal tissue from individuals with colorectal cancer adenomas and carcinomas as well as in healthy individuals, in order to determine at which stages a dysregulated ratio of matriptase/HAI-1 mRNA is present during carcinogenesis.MethodsUsing quantitative RT-PCR, we have determined the mRNA levels for matriptase and HAI-1 in colorectal cancer tissue (n = 9), severe dysplasia (n = 15), mild/moderate dysplasia (n = 21) and in normal tissue from the same individuals. In addition, corresponding tissue was examined from healthy volunteers (n = 10). Matriptase and HAI-1 mRNA levels were normalized to β-actin.ResultsMatriptase mRNA level was lower in carcinomas compared to normal tissue from healthy individuals (p < 0.01). In accordance with this, the matriptase mRNA level was also lower in adenomas/carcinomas combined as compared to their adjacent normal tissue (p < 0.01). HAI-1 mRNA levels in both normal and affected tissue from individuals with severe dysplasia or carcinomas and in affected tissue with mild/moderate dysplasia were all significantly lower than mRNA levels observed in corresponding tissue from healthy control individuals. HAI-1 mRNA was lower in carcinomas as compared to normal tissue from healthy individuals (p < 0.001). HAI-1 mRNA levels were significantly lower in tissue displaying mild/moderate (p < 0.001) and severe (p < 0.01) dysplasia compared to normal tissue from the same patients. Both adenomas and carcinomas displayed a significantly different matriptase/HAI-1 mRNA ratio than corresponding normal tissue from healthy control individuals (p < 0.05). In addition statistically significant difference (p < 0.001) could be observed between mild/moderate and severe adenomas and their adjacent normal tissue.ConclusionOur results show that dysregulation of the matriptase/HAI-1 mRNA ratio occurs early during carcinogenesis. Future studies are required to clarify whether the dysregulated matriptase/HAI-1 ratio was causing the malignant progression or is a consequence of the same.

Meat, vegetables and genetic polymorphisms and the risk of colorectal carcinomas and adenomas

BackgroundThe risk of sporadic colorectal cancer (CRC) is mainly associated with lifestyle factors, particularly dietary factors. Diets high in red meat and fat and low in fruit and vegetables are associated with an increased risk of CRC. The dietary effects may be modulated by genetic polymorphisms in biotransformation genes. In this study we aimed to evaluate the role of dietary factors in combination with genetic factors in the different stages of colorectal carcinogenesis in a Norwegian population.MethodsWe used a case-control study design (234 carcinomas, 229 high-risk adenomas, 762 low-risk adenomas and 400 controls) to test the association between dietary factors (meat versus fruit, berries and vegetables) genetic polymorphisms in biotransformation genes (GSTM1, GSTT1, GSTP1 Ile105Val, EPHX1 Tyr113His and EPHX1 His139Arg), and risk of colorectal carcinomas and adenomas. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression.ResultsA higher ratio of total meat to total fruit, berry and vegetable intake was positively associated with both high and low-risk adenomas, with approximately twice the higher risk in the 2nd quartile compared to the lowest quartile. For the high-risk adenomas this positive association was more obvious for the common allele (Tyr allele) of the EPHX1 codon 113 polymorphism. An association was also observed for the EPHX1 codon 113 polymorphism in the low-risk adenomas, although not as obvious.ConclusionAlthough, the majority of the comparison groups are not significant, our results suggest an increased risk of colorectal adenomas in individuals for some of the higher ratios of total meat to total fruit, berry and vegetable intake. In addition the study supports the notion that the biotransformation enzymes GSTM1, GSTP1 and EPHX1 may modify the effect of dietary factors on the risk of developing colorectal carcinoma and adenoma.

Effects of polymorphisms in ERCC1, ASE-1 and RAI on the risk of colorectal carcinomas and adenomas: a case control study

BackgroundThe risk of sporadic colorectal cancer is mainly associated with lifestyle factors and may be modulated by several genetic factors of low penetrance. Genetic variants represented by single nucleotide polymorphisms in genes encoding key players in the adenoma carcinoma sequence may contribute to variation in susceptibility to colorectal cancer. In this study, we aimed to evaluate whether the recently identified haplotype encompassing genes of DNA repair and apoptosis, is associated with increased risk of colorectal adenomas and carcinomas.MethodsWe used a case-control study design (156 carcinomas, 981 adenomas and 399 controls) to test the association between polymorphisms in the chromosomal region 19q13.2-3, encompassing the genes ERCC1, ASE-1 and RAI, and risk of colorectal adenomas and carcinomas in a Norwegian cohort. Odds ratio (OR) and 95% confidence interval (CI) were estimated by binary logistic regression model adjusting for age and gender.ResultsThe ASE-1 polymorphism was associated with an increased risk of adenomas, OR of 1.39 (95% CI 1.06–1.81), which upon stratification was apparent among women only, OR of 1.66 (95% CI 1.15–2.39). The RAI polymorphism showed a trend towards risk reduction for both adenomas (OR of 0.70, 95% CI 0.49–1.01) and carcinomas (OR of 0.49, 95% CI 0.21–1.13) among women, although not significant. Women who were homozygous carriers of the high risk haplotype had an increased risk of colorectal cancer, OR of 2.19 (95% CI 0.95–5.04) compared to all non-carriers although the estimate was not statistically significant.ConclusionWe found no evidence that the studied polymorphisms were associated with risk of adenomas or colorectal cancer among men, but we found weak indications that the chromosomal region may influence risk of colorectal cancer and adenoma development in women.

Association between Frequency of Chromosomal Aberrations and Cancer Risk Is Not Influenced by Genetic Polymorphisms in GSTM1 and GSTT1

Background The frequency of chromosomal aberrations (CA) in peripheral blood lymphocytes of healthy individuals has been associated with cancer risk. It is presently unclear whether this association is influenced by individual susceptibility factors such as genetic polymorphisms of xenobiotic-metabolizing enzymes. Objectives To evaluate the role of polymorphisms in glutathione S-transferase (GST) M1 (GSTM1) and theta 1 (GSTT1) as effect modifiers of the association between CA and cancer risk. Methods A case–control study was performed pooling data from cytogenetic studies carried out in 1974–1995 in three laboratories in Italy, Norway, and Denmark. A total of 107 cancer cases were retrieved from national registries and matched to 291 controls. The subjects were classified as low, medium, and high by tertile of CA frequency. The data were analyzed by setting up a Bayesian model that included prior information about cancer risk by CA frequency. Results The association between CA frequency and cancer risk was confirmed [ORmedium (odds ratio)medium = 1.5, 95% credibility interval (CrI), 0.9–2.5; ORhigh = 2.8, 95% CrI, 1.6–4.6], whereas no effect of the genetic polymorphism was observed. A much stronger association was seen in the Italian subset (ORhigh= 9.4, 95% CrI, 2.6–28.0), which was characterized by a lower technical variability of the cytogenetic analysis. CA level was particularly associated with cancer of the respiratory tract (ORhigh= 6.2, 95% CrI, 1.5–20.0), the genitourinary tract (ORhigh = 4.0, 95% CrI, 1.4–10.0), and the digestive tract (ORhigh = 2.8, 95% CrI, 1.2–5.8). Conclusions Despite the small size of the study groups, our results substantiate the cancer risk predictivity of CA frequency, ruling against a strong modifying effect of GSTM1 and GSTT1 polymorphisms.

A single nucleotide polymorphism in BMP15 is associated with high response to ovarian stimulation

There is substantial variability in ovarian response to exogenous gonadotrophins in women undergoing ovarian stimulation for IVF. Genetic variation in signalling pathways of the ovary may influence ovarian stimulation outcome. One previous study showed an association between single nucleotide polymorphisms (SNP) in the gene for bone morphogenetic protein 15 (BMP15) and ovarian hyperstimulation syndrome (OHSS). This article presents a retrospective case-controlled genetic-association study designed to test the association between SNP in the BMP15 gene and two clinically important outcomes of ovarian stimulation: low and high response. Blood samples from 53 high responders, 38 low responders and 100 controls were analysed for five SNP of interest. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by a multivariate logistic regression model. We found an association between the BMP15 -9G allele and high response to ovarian stimulation (OR=2.7, 95% CI=1.3-5.7). This association confirms previous findings in a different population and strengthens the case for an association between this SNP and ovarian stimulation outcome.

Increased mRNA expression levels of ERCC1, OGG1 and RAI in colorectal adenomas and carcinomas

BackgroundThe majority of colorectal cancer (CRC) cases develop through the adenoma-carcinoma pathway. If an increase in DNA repair expression is detected in both early adenomas and carcinomas it may indicate that low repair capacity in the normal mucosa is a risk factor for adenoma formation.MethodsWe have examined mRNA expression of two DNA repair genes, ERCC1 and OGG1 as well as the putative apoptosis controlling gene RAI, in normal tissues and lesions from 36 cases with adenomas (mild/moderat n = 21 and severe n = 15, dysplasia) and 9 with carcinomas.ResultsComparing expression levels of ERCC1, OGG1 and RAI between normal tissue and all lesions combined yielded higher expression levels in lesions, 3.3-fold higher (P = 0.005), 5.6-fold higher(P < 3·10-5) and 7.7-fold higher (P = 0.0005), respectively. The levels of ERCC1, OGG1 and RAI expressions when comparing lesions, did not differ between adenomas and CRC cases, P = 0.836, P = 0.341 and P = 0.909, respectively. When comparing expression levels in normal tissue, the levels for OGG1 and RAI from CRC cases were significantly lower compared to the cases with adenomas, P = 0.012 and P = 0.011, respectively.ConclusionOur results suggest that increased expression of defense genes is an early event in the progression of colorectal adenomas to carcinomas.

Genetic Diagnosis of Charcot-Marie-Tooth Disease in a Population by Next-Generation Sequencing

Charcot-Marie-Tooth (CMT) disease is the most prevalent inherited neuropathy. Today more than 40 CMT genes have been identified. Diagnosing heterogeneous diseases by conventional Sanger sequencing is time consuming and expensive. Thus, more efficient and less costly methods are needed in clinical diagnostics. We included a population based sample of 81 CMT families. Gene mutations had previously been identified in 22 families; the remaining 59 families were analysed by next-generation sequencing. Thirty-two CMT genes and 19 genes causing other inherited neuropathies were included in a custom panel. Variants were classified into five pathogenicity classes by genotype-phenotype correlations and bioinformatics tools. Gene mutations, classified certainly or likely pathogenic, were identified in 37 (46%) of the 81 families. Point mutations in known CMT genes were identified in 21 families (26%), whereas four families (5%) had point mutations in other neuropathy genes, ARHGEF10, POLG, SETX, and SOD1. Eleven families (14%) carried the PMP22 duplication and one family carried a MPZ duplication (1%). Most mutations were identified not only in known CMT genes but also in other neuropathy genes, emphasising that genetic analysis should not be restricted to CMT genes only. Next-generation sequencing is a cost-effective tool in diagnosis of CMT improving diagnostic precision and time efficiency.

Single nucleotide polymorphisms in the anti-Müllerian hormone signalling pathway do not determine high or low response to ovarian stimulation

There is substantial variability in ovarian response to exogenous gonadotrophins in women undergoing ovarian stimulation for IVF. Genetic variation in signalling pathways of the ovary could influence ovarian stimulation outcome. Studies have shown a correlation between the serum concentration of anti-Müllerian hormone (AMH) and ovarian stimulation outcome. This paper present a retrospective case-controlled genetic association study designed to test the association between single nucleotide polymorphisms (SNP) in the AMH signalling pathway and two clinically important outcomes of ovarian stimulation: low and high response. Blood samples from 53 high responders, 38 low responders and 100 controls were analysed for eight SNP of interest. Odds ratios and 95% confidence intervals were estimated by a binary logistic regression model adjusting for age and body mass index. As far as is known, this is the first report on the influence of these SNP, present in approximately 19% of women, on ovarian stimulation outcome. No statistically significant association was found between any of the SNP studied and high or low response to ovarian stimulation. It seems unnecessary to detect these SNP when applying the serum concentration of AMH as a predictor of ovarian response to stimulation. Many infertile couples are treated by IVF. Part of this treatment is to pharmacologically stimulate the ovaries to develop many oocytes simultaneously. This process is called ovarian stimulation. Some women respond either too little (low responders) or too much (high responders) to ovarian stimulation. Both these situations are unfavourable to the woman. This study evaluates whether these chances of having one of these two outcomes of ovarian stimulationare influenced by variation in the gene for anti-Müllerian hormone (AMH) or its receptor. This is done by taking blood samples from three groups of patients: low responders, high responders and controls with a normal response. These blood samples were analysed to see if the variation in the genes for AMH or its receptor were different in the three groups. They were not, and so we conclude that the genetic variation that exists in the AMH and receptor signalling pathway is not a major determinant of ovarian stimulation outcome.

Charcot-Marie-Tooth caused by a copy number variation in myelin protein zero

INTRODUCTION Charcot-Marie-Tooth disease (CMT) is the most common inherited disorder of the peripheral nervous system. The majority has a duplication of the peripheral myelin protein 22. CMT is otherwise caused by point mutations or small insertions/deletions in one of the 44 known CMT genes. METHODS AND RESULTS Conventional sequencing of six CMT genes were followed by Multiplex Ligation-dependent Probe Amplification (MLPA), array Comparative Genomic Hybridization (aCGH) and breakpoint analysis in a large Norwegian CMT pedigree. Affected had an extra copy of the myelin protein zero (MPZ) gene. CONCLUSION To our knowledge this is the first non-peripheral myelin protein 22 copy number variation to cause Charcot-Marie-Tooth disease.