Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Variant confidence”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed2002

Thrombospondin-2 polymorphism is associated with a reduced risk of premature myocardial infarction.

OBJECTIVE: Recently, polymorphisms in thrombospondin (THBS) genes coding for THBS-1 (N700S), THBS-2 (T>G substitution in 3'-untranslated region), and THBS-4 (A387P) genes were proposed to modulate the risk of premature coronary artery disease (CAD) or myocardial infarction (MI). It was our objective to verify this hypothesis in an independent cohort. METHODS AND RESULTS: We performed a case-control study among patients (n=503) referred to our institution for symptomatic CAD that occurred before the age of 50 years and a group of age- and sex-matched population-based controls free of CAD (n=1071). The THBS-1 variant allele was not associated with an altered risk of premature CAD or MI. Homozygosity for the THBS-2 variant allele and the THBS-4 variant (387P) allele was significantly associated with a reduced risk of premature MI compared with wild-type individuals (OR=0.44, 0.24 to 0.84 and OR=0.43, 0.22 to 0.85, respectively). The latter observation is in contrast with a previous report, although confidence intervals overlap. CONCLUSIONS: We conclude that a relationship between the THBS-1 N700S polymorphism and premature CAD is unlikely. For the THBS-4 A387P polymorphism, additional studies are required to elucidate its role in premature CAD. Finally, we conclude that the THBS-2 polymorphism is associated with a reduced risk of premature MI.

Adult↗
PubMed2003

Role of MTHFR genetic polymorphisms in the susceptibility to childhood acute lymphoblastic leukemia.

The central role of methylenetetrahydrofolate reductase (MTHFR) in the folate metabolism renders MTHFR gene polymorphisms (C677T and A1298C) potential modulators of a variety of disorders whose development depends on folate/homocysteine imbalance. Here, we provide additional evidence on the protective role of these polymorphisms in acute lymphoblastic leukemia (ALL), the most common pediatric cancer. A case-control study was conducted in 270 ALL patients and 300 healthy controls of French-Canadian origin. The TT677/AA1298 and CC677/CC1298 individuals were associated with reduced risk of ALL (crude odds ratio [OR] = 0.4; 95% confidence interval [CI], 0.2-0.9; and OR = 0.3; 95% CI, 0.1-0.6; respectively). Further stratification in patients born before and after January 1996 (approximate time of Health Canada recommendation for folic acid supplement in pregnancy) revealed that the protective effect of MTHFR variants is accentuated and present only in children born before 1996. Similar results were obtained when a transmission disequilibrium test was performed on a subset of children (n = 95) in a family-based study. This finding suggests gene-environment interaction and its role in the susceptibility to childhood ALL, which is consistent with previous findings associating either folate deficiency or MTHFR polymorphisms with risk of leukemia.

Case-Control Studies↗
PubMed2025

A comprehensive integration of data on the association of ITPKC polymorphisms with susceptibility to Kawasaki disease: a meta-analysis.

BACKGROUND: This study aims to conduct a comprehensive meta-analysis of existing research to define clear associations between variations in the ITPKC gene and the risk of developing Kawasaki disease (KD). METHODS: A comprehensive search was conducted across multiple databases, including but not limited to PubMed, Scopus, EMBASE, and CNKI, up to June 1, 2024, to gather relevant information. This search utilized keywords and MeSH terms related to hyperbilirubinemia and genetic factors. The inclusion criteria encompassed original case-control, longitudinal, or cohort studies. Correlations were analyzed as odds ratios (ORs) with 95% confidence intervals (CIs) using Comprehensive Meta-Analysis software. RESULTS: Eighteen case-control studies with 5,434 KD cases and 9,419 controls were analyzed. Of these, ten studies assessed 3,129 KD cases and 6,172 controls for the rs28493229 variant, four examined 1,039 cases and 1,688 controls for the rs2290692 variant, two focused on 595 cases and 820 controls for the rs7251246 variant, and two investigated 671 cases and 739 controls for the rs10420685 variant. Results showed a significant association between the rs28493229 polymorphism and increased KD risk across all five genetic models. Subgroup analysis indicated this polymorphism correlates with KD susceptibility in Asians but not in the Chinese population. In contrast, no associations were found between the rs2290692, rs7251246, and rs10420685 polymorphisms and KD risk. CONCLUSIONS: Our pooled data indicate a significant association between the ITPKC rs28493229 polymorphism's minor allele and an increased risk of developing KD, suggesting this variant may enhance susceptibility. Conversely, SNPs rs2290692, rs7251246, and rs10420685 do not demonstrate a statistically significant relationship with KD.

Humans↗
PubMed1992

Uncertainty variants of population forecasts.

"When using population forecasts it is important to take into account the degree of uncertainty of the results. For that reason the Netherlands Central Bureau of Statistics publishes low and high variants next to the most probable medium variant.... The width of the interval between the variants is based on an analysis of previous forecast errors. The degree of uncertainty of the various forecast results turns out to vary strongly.... On the basis of a statistical time-series model of forecast errors of total population growth, a confidence interval of total population size can be estimated."

Demography↗
PubMed1994

Strong link between the alpha 1-antitrypsin PiZ allele and Wegener's granulomatosis.

OBJECTIVES: To ascertain whether a relationship exists between the PiZ alpha 1-antitrypsin (alpha 1AT) variant and antineutrophil cytoplasm antibodies (ANCA)-positive vasculitis in a large group of Swedish patients, and whether analysis for the presence of the PiZ variant might be useful for diagnostic or prognostic purposes. DESIGN: Retrospective cross-sectional study. SETTING: The Department of Internal Medicine, Malmö General Hospital, and the Department of Nephrology, University of Lund, Sweden. SUBJECTS AND MAIN OUTCOME MEASURES: Serum samples from 105 proteinase 3-ANCA-positive patients were analysed using an ELISA with a monoclonal antibody specific for the PiZ-gene product. Complete clinical data were retrieved for 84% (88/105) of the patients, for diagnosis and survival analysis. RESULTS: We identified 17 heterozygotes and one homozygote (P < 0.0001). All 88 patients with available clinical data were considered to have some form of microscopic vasculitis including 66 (75%) diagnosed as having Wegener's granulomatosis (WG), of whom 15 (23%) were PiZ heterozygotes (odds ratio 6.0, 95% confidence interval 3-10). There were no significant differences between PiZ carriers and noncarriers in sex distribution, mean age at onset of disease, interval between onset and inclusion in the study, or in median duration of follow-up (P > 0.2 for all comparisons). During follow-up, 38% (6/16) of the PiZ heterozygotes died, compared with 17% (11/66) of noncarriers of the variant (P= 0.02), which suggests that PiZ heterozygosity may be a marker of poor prognosis. PiZ heterozygotes with systemic vasculitis would not appear to be identifiable by their pretreatment plasma alpha 1AT concentrations, as all such patients in the present study had concentrations within or above the normal range. CONCLUSION: We conclude that heterozygotes for the PiZ variant of the alpha 1AT gene are at greater risk of than the general population of developing WG. Knowledge of such a genetic factor may not only aid our understanding of the mechanism involved in this illness but may also serve as significant prognostic factor in following the course of the disease.

Adolescent↗
PubMed2005

TP53BP2 locus is associated with gastric cancer susceptibility.

We investigated the association of the TP53BP2 locus with gastric cancer susceptibility in a Korean population. We assayed 9 single nucleotide polymorphisms (SNP) in an 82.5 kb region that included the TP53BP2 locus in 233 male gastric cancer patients and 390 unaffected healthy male controls. The allelic frequencies of 4 SNP within TP53BP2, g.206692C>T, g.198267A>T, g.164895G>A and g.152389A>T, differed significantly between cases and controls (p < or = 0.0376). When compared to carriers of non-risk alleles, individuals homozygotic for each of the risk alleles had a 50% increase in risk of gastric cancer (age-adjusted odds ratio [OR] > or = 1.48; p < or = 0.0371). Furthermore, these 4 significantly associated SNP were in strong linkage disequilibrium (r2 > or = 0.51). Haplotype analysis showed that individuals with the CAGA haplotype, consisting of the risk alleles at each SNP, had a 1.55-fold higher risk for gastric cancer than individuals with the haplotype TTAT, consisting of the non-risk alleles at each SNP (OR = 1.55; 95% confidence interval [CI] = 1.13-2.14; p = 0.00705). Two other SNP were not polymorphic in the study subjects, whereas the other 3 SNP, located toward the outside of the TP53BP2 locus, were not associated with gastric cancer susceptibility. Although the location of the pathogenic variant is not yet known, our results suggest that the TP53BP2 locus is associated with susceptibility to gastric cancer in the Korean population.

Adult↗
PubMed2001

Amino-acid substitutions in the IKAP gene product significantly increase risk for bronchial asthma in children.

The complex etiology of bronchial asthma (BA), one of the most common inflammatory diseases throughout the world, involves a combination of various genetic and environmental factors. A number of investigators have undertaken linkage and association studies to shed light on the genetic background of BA, but the genetic aspects of this disease are still poorly understood. In the course of a project to screen the entire human genome for single nucleotide polymorphisms (SNPs) that might represent useful markers for large-scale association analyses of common diseases and pharmacogenetic traits, we identified six SNPs within the gene encoding I-kappaB-associated protein (IKAP), a regulator of the NF-kappaB signal pathway. Most of these SNPs were in linkage disequilibrium with each other. We observed a strong allelic association between BA in childhood and two of the SNP sites, T3214A (Cys1072Ser) and C3473T (Pro1158Leu); P = 0.000004 for T3214A and P = 0.0009 for C3473T. T3214A was also associated with BA in adult patients (P = 0.000002), but C3473T was not (P = 0.056). To confirm the above results, we compared estimated frequencies of haplotypes of the six SNPs between BA patients and controls. We found a strong association between BA in childhood and a specific haplotype, TGAAAT, that involved two amino-acid substitutions (819T, 2295G, 2446A, 2490A, 3214A, and 3473T; P = 0.00004, odds ratio, 2.94; 95% confidence interval [CI], 2.48-3.4). On the other hand, haplotype TACGTC, which differed from the TGAAAT haplotype in the last five nucleotides, was inversely correlated with the BA phenotype (P = 0.002; odds ratio, 9.83; 95% CI, 8.35-11.31). These results indicated that specific variants of the IKAP gene, or a variant in linkage disequilibrium with the TGAAAT haplotype, might be associated with mechanisms responsible for early-onset BA.

Adolescent↗
PubMed2005

The HLA-B7 allele confers susceptibility to breast cancer in Spanish women.

BACKGROUND: Several HLA alleles are associated with susceptibility or protection in breast cancer. The particular allele varies depending on the geographical region. A study in a small group of Spanish patients using serological methods found an association with HLA-B7. We undertook a larger study in southern Spain using molecular biology techniques. METHODS: Genotype variants of HLA class I and II were typed by PCR-SSP in 132 breast cancer patients and 382 healthy controls. RESULTS: The frequency of the HLA-B7 allele was increased in the patients compared to the controls (P=0.0019; 95% confidence interval, 1.337-3.409, relative risk=2.135). Bonferroni correction of the P showed it was still significant (P(c)=0.0285). CONCLUSIONS: These results support previous suggestions that HLA-B7 is associated with the development of breast cancer in our area.

Alleles↗
PubMed2002

Folate and breast cancer: the role of polymorphisms in methylenetetrahydrofolate reductase (MTHFR).

Evidence is growing that low folate status may be a factor in the aetiology of several cancers, including breast cancer. The methylenetetrahydrofolate reductase gene (MTHFR), which has a key role in folate metabolism, is polymorphic. We report a case-control study of two functional polymorphisms in MTHFR, dietary folate intake and breast cancer. Sixty-two cases with invasive breast cancer and sixty-six general practice controls participated. Women reporting the highest dietary folate intake had non-significantly reduced breast cancer risk (odds ratio (OR) = 0.49, 95% confidence interval (CI) 0.20-1.20). Risk was significantly lower for the 1298CC genotype compared to AA (OR = 0.24, 95% CI 0.06-0.97). Relative to compound wild-type subjects, compound heterozygotes had moderately reduced risk (OR = 0.47, 95% CI 0.11-1.92) and homozygote variants (677TT and/or 1298CC) greater reduced risk (OR = 0.26, 95% CI 0.07-0.96); the trend was statistically significant. Patterns in risk with regard to genotype and folate combinations are broadly similar those reported for colorectal neoplasia. The roles of MTHFR and folate in breast cancer aetiology are likely to be complex.

Aged↗
PubMed2006

Association study of ACE2 (angiotensin I-converting enzyme 2) gene polymorphisms with coronary heart disease and myocardial infarction in a Chinese Han population.

Results are accumulating that ACE2 (angiotensin I-converting enzyme 2) might act as a protective protein for cardiovascular diseases; however, only a few studies in human populations have been carried out. This prompted us to perform a case-control study to investigate the relationship of ACE2 polymorphisms with CHD (coronary heart disease) and MI (myocardial infarction). Three single nucleotide polymorphisms in the ACE2 gene (1075A/G, 8790A/G and 16854G/C) were genotyped by PCR-RFLP (restriction-fragment-length polymorphism) in 811 patients with CHD (of which 508 were patients with MI) and 905 normal controls in a Chinese population. The polymorphisms were in linkage disequilibrium (r(2)=0.854-0.973). Analyses were conducted by gender, because the ACE2 gene is on the X chromosome. In females, an association was detected with MI for 1075A/G (P=0.026; odds ratio=1.98) and 16854G/C (P=0.028; odds ratio=1.97) in recessive models after adjusting for covariates. In male subjects, two haplotypes (AAG and GGC) were common in frequency. In male subjects not consuming alcohol, the haplotype GGC was associated with a 1.76-fold risk of CHD [95% CI (confidence interval), 1.15-2.69; P=0.007] and a 1.77-fold risk of MI (95% CI, 1.12-2.81; P=0.015) with environmental factors adjusted, when compared with the most common haplotype AAG. In conclusion, the results of the present study indicate that common genetic variants in the ACE2 gene might impact on MI in females, and may possibly interact with alcohol consumption to affect the risk of CHD and MI in Chinese males.

Adult↗
PubMed1998

Enzymatic and molecular biological analysis of palmitoyl protein thioesterase deficiency in infantile neuronal ceroid lipofuscinosis.

Infantile neuronal ceroid lipofuscinosis (INCL) is a neurodegenerative lysosomal storage disease that results from a deficiency of palmitoyl protein thioesterase (PPT), a deacylating enzyme that removes cysteine-bound palmitate from proteins. We developed an in vitro PPT enzyme assay that can be readily used for the clinical diagnosis of both INCL patients and carriers. The substrate is a palmitoylated peptide (IRY[14C]palmitoyl-CWLRR) synthesized by reacting [14C] palmitoyl-CoA with a synthetic octapeptide from the PNS P0 glycoprotein. The PPT assay performed in immortalized lymphoblastoid B-cells or the postmortem brain homogenate showed the optimal enzyme activity at pH 5.0, consistent with the findings that PPT is a lysosomal enzyme. PPT activity in lymphoblasts from INCL patients was <4% of that of control lymphoblasts. In addition, obligatory carriers showed 74% of the control activity. Other pathological controls, including the juvenile form of NCL, showed PPT activities that were not different from normal. Furthermore, one brain sample from an INCL patient contained only 7% PPT activity when compared with an unaffected brain. Thus, the enzyme activity assay gives a confident diagnosis of INCL. In contrast, when the total RNA extract from lymphoblasts was probed with 32P-labeled PPT by northern blot analysis, the level of transcript varied among independent INCL families and was not related to PPT activity. In conclusion, whereas variant genetic modifications result in PPT deficiency, all giving similar INCL phenotype, both affected patients and heterozygote carriers can now be screened with a reliable in vitro PPT assay.

B-Lymphocytes↗
PubMed1999

Cluster of uterine mullerian adenosarcoma in the Washington, DC metropolitan area with high incidence of sarcomatous overgrowth.

Mullerian adenosarcoma is an uncommon variant of uterine sarcoma. Twelve uterine adenosarcomas were diagnosed during a 42-month period at the Washington Hospital Center in Washington, DC. Based on estimated incidence data derived from the US Department of Defense beneficiary population, an estimated relative risk of 15.4 (95% confidence interval, 7.7-31.0) was calculated, indicating a significantly increased incidence of adenosarcoma in the population studied (p<0.0000001). Among 10 patients who underwent hysterectomy, six (60%) of their tumors had sarcomatous overgrowth. In comparison with the previously reported proportion of adenosarcomas with sarcomatous overgrowth, approximately 16%, the proportion with sarcomatous overgrowth was significantly higher than expected (p<0.01). Mullerian adenosarcoma with sarcomatous overgrowth was first described in 1989 and suggests that the cluster of adenosarcomas reported herein may be due in part to the current classification of some uterine tumors as adenosarcoma with sarcomatous overgrowth that previously would have been classified as other types of uterine sarcoma. Nonetheless, even after reviewing and updating the classification of all sarcomas diagnosed at the Washington Hospital Center from 1985 to 1998, the ratio of adenosarcomas to uterine adenocarcinomas during the 1994-1998 period was 4.7 times (p<0.005) that of the 1985-1993 period, suggesting a more modest but real increase in the occurrence of this tumor. Correct classification of mullerian adenosarcomas with sarcomatous overgrowth is important because the limited available data suggest that the prognosis is notably worse than that for adenosarcomas without sarcomatous overgrowth.

Adenosarcoma↗
PubMed1994

Molecular phylogeny of part of the env gene of HIV-1 strains isolated in Côte d'Ivoire.

OBJECTIVES: To examine the genetic variation of HIV-1 isolates in Abidjan, Côte d'Ivoire, and to determine the extent to which phylogenetic trees based on sequence information of part of the env gene containing the principal neutralizing domain are representative for documenting genetic variability. DESIGN: Phylogenetic comparison of 13 HIV-1 strains isolated from patients in Abidjan with previously documented HIV-1 strains of different geographic origin. METHODS: To sequence a 900 base-pair fragment of the env gene containing V3, V4, V5 and the beginning of gp41 of three to four clones per isolate. Phylogenetic tree analysis was performed with the software package TREECON. RESULTS: Eleven HIV-1 isolates of Abidjan were classified as genotype A, while two were classed as genotypes B and D. Intra-genotype A distances at the nucleotide level were a maximum of 14.1%. Inter-genotype distances between genotype A and genotypes B, C, and D varied from 16.0 to 22.6%. Phylogenetic trees, based on sequence data of a 300 base-pair fragment containing the V3 loop, showed significant differences in tree topology and statistical confidence with phylogenetic trees based on sequence data of the 900 base-pair env fragment. CONCLUSIONS: Genotype A Côte d'Ivoire HIV-1 strains, which comprise 11 out of 13 isolates, predominate in Abidjan, which may indicate a local burst of particular variants. Phylogenetic trees should be interpreted with caution when based on a more limited number of nucleotides, such as the V3 region.

Base Sequence↗
PubMed1999

Effects of plasma HIV RNA, CD4+ T lymphocytes, and the chemokine receptors CCR5 and CCR2b on HIV disease progression in hemophiliacs. Hemophilia Growth and Development Study.

We have investigated the effects of plasma HIV RNA, CD4+ T lymphocytes and chemokine receptors CCR5 and CCR2b on HIV disease progression in hemophiliacs. We prospectively observed during follow-up 207 HIV-infected hemophiliacs in the Hemophilia Growth and Development Study. Plasma HIV RNA was measured on cryopreserved plasma from enrollment using the Chiron Corporation bDNA (version 2.0) assay. Genoytpe variants CCR2b-641 and CCR5-delta32 were detected using standard molecular techniques. Those with the mutant allele for CCR2b, and to a lesser extent CCR5, had lower plasma HIV RNA, and higher CD4+ T lymphocytes than did those without these genetic variants. After controlling for the effects of plasma HIV RNA and CD4+ T lymphocytes, those with the CCR2b mutant allele compared with those wild-type, had a trend toward a lower risk of progression to AIDS, adjusted relative hazard of 1.94 (95% confidence interval [CI], 0.9-4.18; p = .092), and AIDS-related death, relative hazard 1.97 (95% CI, 0.98-4.00; p = .059). We conclude that plasma HIV RNA, CD4+ T lymphocytes, and CCR genotypes are correlated, and the protective affect of CCR2b against HIV disease progression is not completely explained by plasma HIV RNA or CD4+ T-lymphocyte number.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Barriers to accurate diagnosis and effective management of heart failure in primary care: qualitative study.

OBJECTIVE: To ascertain the beliefs, current practices, and decision making of general practitioners in the diagnosis and management of suspected heart failure in primary care, with a view to identifying barriers to good care. DESIGN: A qualitative approach using focus groups with 30 general practitioners from four primary care groups. The sampling strategy was stratified and purposive. The contents of interviews were transcribed and analysed according to the principles of "pragmatic variant" grounded theory. SETTING: North east England. RESULTS: Three categories of difficulties contribute to variations in medical practice and to the reasons why general practitioners experience difficulties in diagnosing and managing heart failure. The first is uncertainty about clinical practice, including lack of confidence in establishing an accurate diagnosis and worries about using angiotensin converting enzyme inhibitors, beta blockers, and spironolactone in patients who are often elderly and frail, with comorbidity and polypharmacy. The second is a lack of awareness of relevant research evidence in what was perceived to be a complex and rapidly changing therapeutic field. Doubts about the applicability of research findings in primary care, and fear of information overload also emerged. The third category consists of influences of individual preference and local organisational factors. Medical training, negative clinical experiences, and outside agencies influenced the behaviour of general practitioners and professional culture. Local factors included the availability of diagnostic services, resources (such as accessible cardiologists), and interactions between professionals in primary or secondary care, and they seemed to shape the practice and decision making processes in primary care. CONCLUSIONS: The national service framework for coronary heart disease stresses that the substandard care of patients with heart failure is unacceptable. This study identified barriers to be overcome across primary and secondary care in implementation strategies that are specific to the locality and multifaceted. Single strategies--for example, the provision of guidelines--are unlikely to have an impact on clinical outcomes, and new, conjoint models of care need to be explored.

Adult↗
PubMed2005

Genetic polymorphisms of CYP2E1, GSTT1, GSTP1, GSTM1, ALDH2, and ODC and the risk of advanced precancerous gastric lesions in a Chinese population.

There have been few studies of the associations of genetic polymorphisms with precancerous gastric lesions. We conducted a cross-sectional study to compare the prevalences of several genetic polymorphisms in 302 subjects with mild chronic atrophic gastritis with prevalences in 606 subjects with deep intestinal metaplasia or dysplasia. This stratified random sample of 908 subjects was selected and analyzed for genetic polymorphisms from 2,628 individuals who had gastric biopsies with histopathology in 1989 in Linqu County, Shandong Province, China. In subjects with mild chronic atrophic gastritis, the frequencies of the variant (less common) alleles of CYP2E1 RsaI, CYP2E1 DraI, GSTP1, ALDH2, and ODC were, respectively, 0.156, 0.201, 0.189, 0.190, and 0.428. The frequencies of the null genotypes of GSTM1 and GSTT1 in the mild chronic atrophic gastritis group were 0.509 and 0.565, respectively. Comparing mild chronic atrophic gastritis with deep intestinal metaplasia or any degree of dysplasia, we found no statistically significant associations with any genotype from these loci for dominant, additive, or recessive inheritance models. There was no statistically significant evidence of multiplicative interactions between any pair of genotypes based on CYP2E1 RsaI, CYP2E1 DraI, GSTP1, GSTM1, or GSTT1; nor between Helicobacter pylori status and any of these five loci; nor between smoking status and GSTP1, GSTM1, or GSTT1; nor between alcohol consumption and ALDH2. Statistically significant interactions were noted between salt consumption and GSTP1 and between sour pancake consumption and CYP2E1 RsaI. There was, moreover, a statistically significant interaction (odds ratio, 1.78; 95% confidence interval, 1.03-3.08) between CYP2E1 DraI and smoking at least one cigarette per day. A positive but not statistically significant interaction was also seen between CYP2E1 RsaI and smoking status. These polymorphisms do not seem to govern progression from mild chronic atrophic gastritis to advanced precancerous gastric lesions, but the effects of smoking may be accentuated in individuals carrying variants of CYP2E1.

Aldehyde Dehydrogenase↗
PubMed2006

Cigarette smoking, N-acetyltransferase genes and the risk of advanced colorectal adenoma.

BACKGROUND: Cigarette use is associated with greater risk for colorectal adenoma, a colorectal cancer precursor. N-acetyltransferases, NAT1 and NAT2, are important enzymes involved in the metabolism of aromatic amine carcinogens present in cigarette smoke. Our interest is in the polymorphisms within the NAT1 and NAT2 genes that influence the tobacco-colorectal tumor relationship by impacting on the metabolic activation and detoxification of tobacco smoke-derived carcinogens. METHODS: In the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, we compared NAT1 and NAT2 gene variant distributions for 772 cases with left-sided advanced adenoma and 777 gender and age-matched controls. Individual NAT1 and NAT2 diplotypes were assigned and NAT2 acetylator phenotypes were derived. RESULTS: Risks for advanced colorectal adenoma were significantly increased among recent smokers (current smokers or those who quit less than 10 years ago) (odds ratio [OR] = 2.3, 95% confidence interval [CI]: 1.7-3.1) and among those who smoked more than 20 cigarettes per day (OR = 1.7, 95% CI: 1.3-2.2), compared with nonsmokers. Risk decreased with increasing NAT2 phenotypic activity (0: slow, 1: intermediate, and 2: rapid) (OR trend: 0.8; 95% CI: 0.7-1.0, p-trend = 0.04) overall. When stratified by smoking status, significant phenotype-associated trends were observed among recent smokers (OR trend = 0.4, 95% CI: 0.3-0.7, p trend <0.001) (p-interaction = 0.02), but not among past or nonsmokers. Diplotypes most strongly associated with lower risks in smokers were NAT2*4/*5B (OR = 0.3, 95% CI: 0.1-0.8, p = 0.01) and NAT2*4/*4 (OR = 0.2, 95% CI: 0.04-0.7, p = 0.02), categorized as intermediate and rapid acetylators, respectively. One NAT1 diplotype, NAT1*4/*10 (OR = 0.5, 95% CI: 0.3-0.9, p = 0.03), was also associated with a decreased risk in smokers. CONCLUSIONS: Our study indicated that NAT2 gene variants associated with a slow acetylator phenotype were more susceptible to the effects of tobacco smoking with respect to adenoma risk, providing leads for disease prevention.

Adenoma↗