Increased risk of ovarian hyperstimulation syndrome following controlled ovarian hyperstimulation in patients with vascular endothelial growth factor +405 cc genotype.

Ovarian hyperstimulation syndrome (OHSS) is a serious complication following controlled ovarian hyperstimulation (COH) for in vitro fertilization. OHSS has a range of clinical features from mild abdominal distention to severe thromboembolic events. Several clinical manifestations of OHSS such as ascites and hemoconcentration can be attributed to increased vascular permeability. Vascular endothelial growth factor (VEGF) and its receptor VEGFR2 have been identified as an important signaling system in mediating this increase. There is considerable genetic variation in the VEGF/R2 signaling system. We present the first study to examine if single nucleotide polymorphisms (SNPs) in the genes encoding the VEGF/R2 signaling system are associated with OHSS following COH. Blood samples from 53 OHSS patients and 100 controls were analyzed for six SNPs 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 VEGF +405cc genotype and OHSS (OR 3.4, 95% CI 1.01-11.7). This finding requires confirmation from other patient populations.

Influence of GSTM1, GSTT1, GSTP1, NAT1, NAT2, EPHX1, MTR and MTHFR polymorphism on chromosomal aberration frequencies in human lymphocytes.

We have studied the influence of genetic polymorphisms in the xenobiotic-metabolizing genes GSTM1, GSTP1, GSTT1, EPHX1, NAT1 and NAT2 and the folate-metabolizing genes MTR and MTHFR on the frequencies of cells with chromosomal aberrations (CAs) in peripheral lymphocytes of Norwegian men. Log-linear Poisson regression models were applied on 357 subjects of whom data on all the polymorphisms examined were available. Total CAs and chromosome-type aberrations (CSAs) were significantly increased by higher age alone, whereas chromatid-type aberrations (CTAs) were elevated by the GSTT1-null genotype and MTHFR codon 222 variant allele and chromatid gaps (CTGs) by EPHX1 high activity genotype and occupational exposure. Stratification by smoking and age (<40 and ≥40 years) showed that the effect of the GSTT1 null and EPHX1 high activity genotypes only concerned (older) smokers, in agreement with the roles of the respective enzymes in detoxification and metabolic activation. The MTHFR codon 222 variant allele was associated with high CTGs in smokers, the MTR codon 919 variant allele with high CTAs in older smokers and the NAT2 fast acetylator genotype with high CTGs in older subjects. Among younger nonsmokers, however, carriers of the MTHFR codon 222 and MTR codon 919 variant alleles showed a decrease in the level of CTGs and total CAs, respectively. In conclusion, polymorphisms of GSTT1, EPHX1, MTHFR, MTR and NAT2 differentially affect the frequency of CTAs, CSAs and CTGs, showing interaction with smoking and age. It appears that CA subtypes rather than total CAs should be considered in this type of studies.

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.

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.

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 [OR(medium) (odds ratio)(medium) = 1.5, 95% credibility interval (CrI), 0.9-2.5; OR(high) = 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 (OR(high)= 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 (OR(high)= 6.2, 95% CrI, 1.5-20.0), the genitourinary tract (OR(high) = 4.0, 95% CrI, 1.4-10.0), and the digestive tract (OR(high) = 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.

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

BACKGROUND: The 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. METHODS: We 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. RESULTS: Comparing 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. CONCLUSION: Our results suggest that increased expression of defense genes is an early event in the progression of colorectal adenomas to carcinomas.

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

BACKGROUND: Genetic 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. METHODS: We 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. RESULTS: The 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. CONCLUSION: Our 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.

Influence of DNA repair gene polymorphisms of hOGG1, XRCC1, XRCC3, ERCC2 and the folate metabolism gene MTHFR on chromosomal aberration frequencies.

We have studied the effect of genetic polymorphisms in the DNA repair genes hOGG1, XRCC1, XRCC3, ERCC2 and the MTHFR gene in the folate metabolism on the frequencies of cells with chromosomal aberrations (CA), chromosome-type aberrations (CSA), chromatid-type aberrations (CTA), chromatid breaks (CTB) and chromatid gaps (CTG) scored in peripheral blood lymphocytes from 651 Norwegian subjects of Caucasian descendant. DNA was extracted from fixed cell suspensions. The log-linear Poisson regression model was used for the combined data which included age, smoking, occupational exposure and genotype for 449 subjects. Our results suggest that individuals carrying the hOGG1 326Cys or the XRCC1 399Gln allele have an increased risk of chromosomal damage, while individuals carrying the XRCC1 194Trp or the ERCC2 751Gln allele have a reduced risk regardless of smoking habits and age. Individuals carrying the XRCC1 280His allele had an increased risk of CSA which was only apparent in non-smokers. This was independent of age. A protective effect of the XRCC3 241Met allele was only found in the older age group in non-smokers for CA, CSA and CTA, and in smokers for CSA. In the youngest age group, the opposite effect was found, with an increased risk for CA, CTA and CTG in smokers. Carrying the MTHFR 222Val allele gave an increased risk for chromosome and chromatid-type aberrations for both non-smokers and smokers, especially for individuals in the older age group, and with variable results in the youngest age group. The variables included in the different regression models accounted, however, for only 4-10% of the variation. The frequency ratio for CTG was significantly higher than for CTA and CTB for only 7 of the 43 comparisons performed. Some of the gap frequencies diverge from the trend in the CA, CSA, CTA and CTB results.

GPX Pro198Leu and OGG1 Ser326Cys polymorphisms and risk of development of colorectal adenomas and colorectal cancer.

Little is known about genetic risk factors for colorectal cancer. We assessed the association between polymorphisms in two genes involved in DNA repair of oxidative stress, GPX and OGG1, and risk of colorectal carcinoma or adenomas. We studied 166 cases with adenocarcinoma, 974 with adenomas and 397 controls recruited from the Norwegian cohort NORCCAP. No associations were found between the polymorphism GPX Pro198Leu and risk of colorectal adenomas or carcinomas. Carriers of the variant allele OGG1 Ser326Cys polymorphism had a lowered risk of colorectal cancer, OR=0.56 (95% confidence interval 0.33-0.95), while no association were found with risk of adenomas. This indicates that a low repair capacity of oxidative DNA damage may not be a risk factor for development of colorectal adenomas or carcinoma.

Single-track sequencing for genotyping of multiple SNPs in the N-acetyltransferase 1 (NAT1) gene.

BACKGROUND: Fast, cheap and reliable methods are needed to identify large populations, which may be at risk in relation to environmental exposure. Polymorphisms in NAT1 (N-acetyl transferase) may be suitable markers to identify individuals at risk. RESULTS: A strategy allowing to address simultaneously 24 various genetic variants in the NAT1 gene using the single sequencing reaction method on the same PCR product is described. A modified automated DNA sequencing using only one of the sequence terminators was used to genotype PCR products in single-track sequencing reactions of NAT1 and was shown to be universal for both DNA sequencing using labeled primers and labeled nucleotides. By this method we detected known SNPs at site T640G, which confers the NAT1*11 allele with frequency of 0.036, further T1088A and C1095A with frequency of 0.172 and 0.188, respectively and a deletion of TAATAATAA in the poly A signal area with a frequency 0.031. All observed frequencies were in Hardy Weinberg equilibrium and comparable to those in Caucasian population. The single-track signatures of the variant genotypes were verified on samples previously genotyped by RLFP. CONCLUSIONS: The method could be of great help to scientists in the field of molecular epidemiology of screening of large populations for known informative biomarkers of susceptibility, such as NAT1.