There is growing evidence linking genetic variations to non–Hodgkin lymphoma (NHL) etiology. To complement ongoing agnostic approaches for identifying susceptibility genes, we evaluated 488 candidate gene regions and their relation to risk for NHL and NHL subtypes.
We genotyped 6,679 tag single nucleotide polymorphisms (SNPs) in 947 cases and 826 population-based controls from a multicenter U.S. case–control study. Gene-level summary of associations were obtained by computing the minimum P value (“minP test”) on the basis of 10,000 permutations. We used logistic regression to evaluate the association between genotypes and haplotypes with NHL. For NHL subtypes, we conducted polytomous multivariate unconditional logistic regression (adjusted for sex, race, age). We calculated P-trends under the codominant model for each SNP.
Fourteen gene regions were associated with NHL (P < 0.01). The most significant SNP associated with NHL maps to the SYK gene (rs2991216, P-trend = 0.00005). The three most significant gene regions were on chromosome 6p21.3 (RING1/RXRB; AIF1; BAT4). Accordingly, SNPs in RING1/RXRB (rs2855429), AIF1 (rs2857597), and BAT4 (rs3115667) were associated with NHL (P-trends ≤ 0.0002) and both diffuse large B-cell and follicular lymphomas (P-trends < 0.05).
Our results suggest potential importance for SYK on chromosome 9 with NHL etiology. Our results further implicate 6p21.3 gene variants, supporting the need for full characterization of this chromosomal region in relation to lymphomagenesis.
Gene variants on chromosome 9 may represent a new region of interesting for NHL etiology. The independence of the reported variants in 6p21.3 from implicated variants (TNF/HLA) supports the need to confirm causal variants in this region
New technologies enabling genome-wide interrogation have led to a large and rapidly growing number of autism spectrum disorder (ASD) candidate genes. Although encouraging, the volume and complexity of these data make it challenging for scientists, particularly non-geneticists, to comprehensively evaluate available evidence for individual genes. Described here is the Gene Scoring module within SFARI Gene 2.0 (https://gene.sfari.org/autdb/GS_Home.do), a platform developed to enable systematic community driven assessment of genetic evidence for individual genes with regard to ASD.
Autism spectrum disorder (ASD) is one of the most prevalent and highly heritable neurodevelopmental disorders in humans. There is significant evidence that the onset and severity of ASD is governed in part by complex genetic mechanisms affecting the normal development of the brain. To date, a number of genes have been associated with ASD. However, the temporal and spatial co-expression of these genes in the brain remain unclear. To address this issue, we examined the co-expression network of 26 autism genes from AutDB (http://mindspec.org/autdb.html), in the framework of 3,041 genes whose expression energies have the highest correlation between the coronal and sagittal images from the Allen Mouse Brain Atlas database (http://mouse.brain-map.org). These data were derived from in situ hybridization experiments conducted on male, 56-day old C57BL/6J mice co-registered to the Allen Reference Atlas, and were used to generate a normalized co-expression matrix indicating the cosine similarity between expression vectors of genes in this database. The network formed by the autism-associated genes showed a higher degree of co-expression connectivity than seen for the other genes in this dataset (Kolmogorov–Smirnov P = 5×10−28). Using Monte Carlo simulations, we identified two cliques of co-expressed genes that were significantly enriched with autism genes (A Bonferroni corrected P<0.05). Genes in both these cliques were significantly over-expressed in the cerebellar cortex (P = 1×10−5) suggesting possible implication of this brain region in autism. In conclusion, our study provides a detailed profiling of co-expression patterns of autism genes in the mouse brain, and suggests specific brain regions and new candidate genes that could be involved in autism etiology.
Autism spectrum disorder (ASD) is a complex neurodevelopmental condition associated with many different genes. However, the neuroanatomical and functional properties of these genes in the brain are largely unknown. Here we examined the co-expression network of 26 genes associated with ASD, using data from the Allen Mouse Brain Atlas, which provides a whole-genome, high-resolution map of gene expression pattern in the adult mouse brain. We discovered that autism genes are significantly more co-expressed than expected by chance, suggesting common neuro-functional properties. We then examined the spatial properties of co-expression modules that are highly enriched with autism genes. Consequently, we found that genes in two of these modules are significantly over-expressed in the cerebellar cortex, and particularly in sections that are predominantly populated by granular cells. These findings provide the essential link between gene networks associated with ASD and specific brain regions, and hence lay out a basis for further exploration of the particular neuronal circuits involved in ASD etiology.
Copy number variants (CNVs) are thought to play an important role in the predisposition to autism spectrum disorder (ASD). However, their relatively low frequency and widespread genomic distribution complicates their accurate characterization and utilization for clinical genetics purposes. Here we present a comprehensive analysis of multi-study, genome-wide CNV data from AutDB (http://mindspec.org/autdb.html), a genetic database that accommodates detailed annotations of published scientific reports of CNVs identified in ASD individuals. Overall, we evaluated 4,926 CNVs in 2,373 ASD subjects from 48 scientific reports, encompassing ∼2.12×109 bp of genomic data. Remarkable variation was seen in CNV size, with duplications being significantly larger than deletions, (P = 3×10−105; Wilcoxon rank sum test). Examination of the CNV burden across the genome revealed 11 loci with a significant excess of CNVs among ASD subjects (P<7×10−7). Altogether, these loci covered 15,610 kb of the genome and contained 166 genes. Remarkable variation was seen both in locus size (20 - 4950 kb), and gene content, with seven multigenic (≥3 genes) and four monogenic loci. CNV data from control populations was used to further refine the boundaries of these ASD susceptibility loci. Interestingly, our analysis indicates that 15q11.2-13.3, a genomic region prone to chromosomal rearrangements of various sizes, contains three distinct ASD susceptibility CNV loci that vary in their genomic boundaries, CNV types, inheritance patterns, and overlap with CNVs from control populations. In summary, our analysis of AutDB CNV data provides valuable insights into the genomic characteristics of ASD susceptibility CNV loci and could therefore be utilized in various clinical settings and facilitate future genetic research of this disorder.
The complement system plays an important role in inflammatory and immune responses, and recent evidence has suggested that it may also play a role in lymphomagenesis. We evaluated the association between genetic variation in complement system genes and risk of non-Hodgkin lymphoma (NHL) in a population-based case–control study conducted among women in Connecticut. Tag SNPs in 30 complement genes were genotyped in 432 Caucasian incident cases and 494 frequency-matched controls. A gene-based analysis that adjusted for the number of tag SNPs genotyped in each gene showed a significant association with NHL overall (P = 0.04) as well as with diffuse large B-cell lymphoma (DLBCL) (P = 0.01) for the C1RL gene. A SNP-based analysis showed that a C>T base substitution for C1RL rs3813729 (odds ratio (OR)CT = 0.60, 95% confidence interval (CI) = 0.42–0.87, Ptrend = 0.0062) was associated with a decreased risk of overall NHL, as well as for DLBCL (ORCT = 0.39, 95% CI = 0.20–0.73; Ptrend = 0.0034). Additionally, SNPs (C2 rs497309, A>C and C3 rs344550, G>C) in two complement genes were positively associated with marginal zone lymphoma (MZL) and C1QG was associated with CLL/SLL, but these results were based on a limited number of cases. Our results suggest a potential role of the complement system in susceptibility to NHL; however, our results should be viewed as exploratory and further replication is needed to clarify these preliminary findings.
lymphoma; C1RL; innate immunity; SNP
Androgens and inflammation have been implicated in the etiology of several cancers, including prostate cancer. Serum androgens have been shown to correlate with markers of inflammation and expression of inflammation-related genes.
In this report, we evaluated associations between 9,932 single nucleotide polymorphisms (SNPs) marking common genetic variants in 774 inflammation-related genes and four serum androgen levels (total testosterone [T], bioavailable T [BioT]; 5α-androstane-3α, 17β-diol glucuronide [3αdiol G], and 4-Androstene-3,17-dione [androstenedione]), in 560 healthy men (median age 64 years) drawn from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Baseline serum androgens were measured by radioimmunoassay. Genotypes were determined as part of the Cancer Genetic Markers of Susceptibility Study genome-wide scan. SNP-hormone associations were evaluated using linear regression of hormones adjusted for age. Gene-based p-values were generated using an adaptive rank truncated product method.
Suggestive associations were observed for two inflammation-related genes and circulating androgen levels (false discovery rate [FDR] q-value<0.1) in both SNP and gene-based tests. Specifically, T was associated with common variants in MMP2 and CD14, with the most significant SNPs being rs893226G>T in MMP2 and rs3822356T>C in CD14 (FDR q-value=0.09 for both SNPs). Other genes implicated in either SNP or gene-based tests were IK with T and BioT, PRG2 with T, and TNFSF9 with androstenedione.
These results suggest possible cross-talk between androgen levels and inflammation pathways, but larger studies are needed to confirm these findings and to further clarify the interrelationship between inflammation and androgens and their effects on cancer risk.
Inflammation; Androgens; Genes; Testosterone; Polymorphism; Single Nucleotide
Several genes that modify risk of factor VIII inhibitors in hemophilia A patients have been identified. Aside from the underlying mutations that cause hemophilia A, inhibitor risk appears to be modified by polymorphisms in various cytokines and immunomodulators, including IL10, TNFα, and CTLA4. HLA haplotypes have not been strong determinants of inhibitor risk.
We sought to confirm previous observations on factor VIII inhibitor risk-modifying genes and to test new candidate genes encoding various otherTH1/TH2 cytokines. We also sought to determine whether normal factor VIII gene polymorphisms affect inhibitor risk in Caucasians.
We studied 915 Caucasian, severe hemophilia A patients (282 inhibitor cases and 633 non-inhibitor controls) Genes were analyzed using 368 tagging SNPs starting 20kb 5′ and ending 10kb 3′ of each gene's coding sequence; four other polymorphisms (factor V Leiden & prothrombin 20210 polymorphisms and two in HFE) were also evaluated.
Haplotypes that increased inhibitor risk were found in IL10 (OR 1.33, P = 0.04), IL12 (OR 1.31, P = 0.04), and IL1α (OR 2.16, P = 0.034). Protective haplotypes were seen in IL2 (OR 0.69, P = 0.008) and IL1β (OR 0.75, P = 0.02). One rare haplotype in the factor VIII gene increased the risk of inhibitor development by nearly four-fold (OR 3.8, P = 0.004).
We replicate previous findings for IL10; identify new associations with IL1, IL2 and IL12; and identify a rare factor VIII haplotype in Caucasians that is associated with increased inhibitor risk.
hemophilia A; inhibitor; factor VIII; IL10; IL2; IL12; IL1
Multiple myeloma (MM) is a B-cell lymphoid malignancy suspected to be associated with immunologic factors. Given recent findings associating single-nucleotide polymorphisms (SNPs) in innate immunity genes with non-Hodgkin lymphoma, we conducted an investigation of innate immune gene variants using specimens from a population-based case-control study of MM conducted in Connecticut women. Tag SNPs (N=1,461) summarizing common variation in 149 gene regions were genotyped in non-Hispanic Caucasian subjects (103 cases, 475 controls). Odds ratios (OR) and 95% confidence intervals (CI) relating SNP associations with MM were computed using unconditional logistic regression, while the MinP test was used to investigate associations with MM at the gene level. We calculated permutation-adjusted P-values and false discovery rates (FDR) to account for the number of comparisons performed in SNP-level and gene-level tests, respectively. Three genes were associated with MM when controlling for a FDR of ≤10%: SERPINE1 (PMinP<0.0001; FDR=0.02), HGF (PMinP=0.0006; FDR=0.06) and CCR7 (PMinP=0.001; FDR=0.08). Two SNPs demonstrated robust associations: SERPINE1 rs2227667 (P=2.1×10−5, Ppermutation=0.03) and HGF rs17501108 (P=5.0×10−5, Ppermutation=0.07). Our findings suggest that genetic variants in SERPINE1 and HGF, and possibly CCR7, are associated with MM risk, and warrant further investigation in other studies.
epidemiology; myeloma; genetics
Genetic variation in immune-related genes may play a role in the development of non-Hodgkin lymphoma (NHL). To test the hypothesis that innate immunity polymorphisms may be associated with NHL risk, we genotyped 144 tag single nucleotide polymorphisms (tagSNPs) capturing common genetic variation within 12 innate immunity gene regions in three independent population-based case-control studies (1946 cases and 1808 controls). Gene-based analyses found IL1RN to be associated with NHL risk (minP = 0.03); specifically, IL1RN rs2637988 was associated with an increased risk of NHL (per-allele odds ratio = 1.15, 95% confidence interval = 1.05 – 1.27; ptrend = 0.003), which was consistent across study, subtype, and gender. FCGR2A was also associated with a decreased risk of the follicular lymphoma NHL subtype (minP = 0.03). Our findings suggest that genetic variation in IL1RN and FCGR2A may play a role in lymphomagenesis. Given that conflicting results have been reported regarding the association between IL1RN SNPs and NHL risk, a larger number of innate immunity genes with sufficient genomic coverage should be evaluated systematically across many studies.
non-Hodgkin lymphoma; immune; innate immunity; genetic variation; single nucleotide polymorphisms
Genome-wide association studies (GWAS) focus on relatively few highly significant loci while less attention is given to other genotyped markers. Employing pathway analysis to existing GWAS data may shed light on relevant biological processes, and illuminate new candidate genes. We employed a pathway-based approach to the breast cancer GWAS data of the National Cancer Institute (NCI) Cancer Genetic Markers of Susceptibility (CGEMS) project that includes 1145 cases and 1142 controls. Pathways were retrieved from three databases: KEGG, BioCarta, and the NCI’s Protein Interaction Database (PID). Genes were represented by their most strongly associated SNP, and an enrichment score (ES) reflecting the overrepresentation of gene-based association signals in each pathway was calculated using a weighted Kolmogorov-Smirnov procedure. Finally, hierarchical clustering was used to identify pathways with overlapping genes, and clusters with excess of association signals were determined by the adaptive rank-truncated product (ARTP) method. A total of 421 pathways containing 3962 genes were included in our study. Of these, three pathways (‘Syndecan-1-mediated signaling ‘, ‘Signaling of Hepatocyte Growth Factor Receptor’ and ‘Growth Hormone Signaling’) were highly enriched with association signals (PES < 0.001, False Discovery Rate (FDR) = 0.118). Our clustering analysis revealed that pathways containing key components of the RAS/RAF/MAPK canonical signaling cascade, were significantly more likely to have excess of association signals than expected by chance (PARTP = 0.0051, FDR = 0.07). These results suggest that genetic alterations associated with these three pathways and one canonical signaling cascade may contribute to breast cancer susceptibility.
Pathways; GWAS; Breast cancer; Susceptibility; Genetics
Elevated incidence of lymphoma has been observed among carriers of rare high-penetrance mutations in DNA repair genes (e.g., Nijmegen breakage syndrome, Ataxia-telangectasia syndrome, etc.). Common gene variants in DNA repair genes may also influence lymphomagenesis.
Study subjects were pooled from three population-based case-control studies of non-Hodgkin lymphoma (NHL) in the US and Australia. A total of 1,946 cases and 1,808 controls were analyzed. A total of 319 tag single nucleotide polymorphisms (SNPs) in 27 DNA repair gene regions were genotyped. Unconditional logistic regression models were used to estimate the relative risk of NHL and NHL subtypes in relation to SNPs. Tail-strength statistics were used to test for the association between DNA repair pathways and NHL or NHL subtypes. The statistical significance of the smallest P-trend within each gene region was estimated by permutation-based resampling methods.
Overall, DNA repair genetic polymorphisms were associated with NHL (P = 0.005). Tests for the double strand break repair (P = 0.02) and nucleotide excision repair (P = 0.04) pathways were also significant. Four gene regions were significantly associated with NHL or NHL subtypes at the 0.05 level: RAD50, BLM, RAD51/FAM82C, and ERCC3/MAP3K2. Specifically, BLM rs441399 (P trend = 0.004) and FAM82C rs2304583 (P trend = 0.001) were associated with follicular lymphoma, and XRCC4 rs13178127 was associated with NHL overall (P trend = 0.006) significantly. In addition, the ERCC3 rs4150506 was associated with reduced risk for marginal zone lymphoma (P trend = 0.002).
These results support the hypothesis that common genetic polymorphisms in human DNA repair genes may modify the risk of NHL.
non-Hodgkin lymphoma; DNA repair; single nucleotide polymorphism; pooled analysis
Lipid peroxidation is considered a unifying mechanistic pathway through which known risk factors induce renal cell carcinoma (RCC). We hypothesized that genes selected apriori for their role in lipid peroxidation would modify cancer risk. We genotyped 635 single nucleotide polymorphisms (SNPs) in thirty-eight candidate genes in 777 Caucasian RCC cases and 1035 controls enrolled in a large European case-control study. Top candidate SNPs were confirmed among 718 Caucasian cases and 615 controls in a second study in the United States. Two of the three SNPs (rs8106822 and rs405509) that replicated in the US study were within a regulatory region of the APOE promoter. The odds ratio (OR) for rs8106822 A>G variant was 1.22AG and 1.41GG (p-trend=0.01) in the European study, 1.05AG and 1.51GG (p-trend=0.03) in the US study, and 1.15AG and 1.44GG (p-trend=0.001) among 1485 cases and 1639 controls combined. The rs405509 G>T variant was associated with risk in the European (OR=0.87TG; OR=0.71TT; p-trend=0.02), the US (OR=0.68TG; OR=0.71TT; p-trend=0.02), and both studies combined (ORTG=0.79; ORTT= 0.71; p-trend=0.001), as was the G-G haplotype (r2=0.64; p=4.7 × 10-4). This association is biologically plausible as SNP rs405509 was shown to modify protein binding and transcriptional activity of the APOE gene in vitro and is in LD with key known variants defining the e2, e3, e4 alleles that modify risk of atherosclerosis, Alzheimer's disease risk, and progression to AIDS. In two large case-control studies, our findings further define a functional region of interest at the APOE locus that increases RCC susceptibility.
In the United States, a black-to-white disparity in age-standardized breast cancer mortality rates emerged in the 1980s and has widened since then.
To further explore this racial disparity, black-to-white rate ratios (RRsBW) for mortality, incidence, hazard of breast cancer death, and incidence-based mortality (IBM) were investigated using data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results program on 244 786 women who were diagnosed with breast cancer from January 1990 through December 2003 and followed through December 2004. A counterfactual approach was used to examine the expected IBM RRsBW, assuming equal distributions for estrogen receptor (ER) expression, and/or equal hazard rates of breast cancer death, among black and white women.
From 1990 through 2004, mortality RRBW was greater than 1.0 and widened over time (age-standardized breast cancer mortality rates fell from 36 to 29 per 100 000 for blacks and from 30 to 22 per 100 000 for whites). In contrast, incidence RRBW was generally less than 1.0. Absolute hazard rates of breast cancer death declined substantially for ER-positive tumors and modestly for ER-negative tumors but were persistently higher for blacks than whites. Equalizing the distributions of ER expression in blacks and whites decreased the IBM RRBW slightly. Interestingly, the black-to-white disparity in IBM RRBW was essentially eliminated when hazard rates of breast cancer death were matched within each ER category.
The black-to-white disparity in age-standardized breast cancer mortality was largely driven by the higher hazard rates of breast cancer death among black women, diagnosed with the disease, irrespective of ER expression, and especially in the first few years following diagnosis. Greater emphasis should be placed on identifying the etiology of these excess hazards and developing therapeutic strategies to address them.
We examined the associations between 21 single nucleotide polymorphisms (SNPs) of eight lipid metabolism genes and lipid levels in a Chinese population.
This study was conducted as part of a population-based study in China with 799 randomly selected healthy residents who provided fasting blood and an in-person interview. Associations between variants and mean lipid levels were examined using a test of trend and least squares mean test in a general linear model.
Four SNPs were associated with lipid levels: LDLR rs1003723 was associated with total cholesterol (p-trend=0.002) and LDL (p-trend=0.01), LDLR rs6413503 was associated with total cholesterol (p-trend=0.05), APOB rs1367117 was associated with apoB (p-trend=0.02), and ABCB11 rs49550 was associated with total cholesterol (p-trend=0.01), triglycerides (p-trend=0.01), and apoA (p-trend=0.01). We found statistically significant effects on lipid levels for LDLR rs6413503 among those with high dairy intake, LPL rs263 among those with high allium vegetable intake, and APOE rs440446 among those with high red meat intake.
We identified new associations between SNPs and lipid levels in Chinese previously found in Caucasians. These findings provide insight into the role of lipid metabolism genes, as well as the mechanisms by which these genes may be linked with disease.
single nucleotide polymorphisms; Chinese; serum lipid levels
The high incidence of lung cancer in Xuanwei County, China has been attributed to exposure to indoor smoky coal emissions that contain polycyclic aromatic hydrocarbons. The inflammatory response induced by coal smoke components may promote lung tumor development. We studied the association between single nucleotide polymorphisms (SNP) in genes involved in innate immunity and lung cancer risk in a population-based case-control study (122 cases and 122 controls) in Xuanwei. A total of 1,360 tag SNPs in 149 gene regions were included in the analysis. FCER2 rs7249320 was the most significant SNP (OR: 0.30; 95% CI: 0.16–0.55; P, 0.0001; false discovery rate value, 0.13) for variant carriers. The gene regions ALOX12B/ALOX15B and KLK2 were associated with increased lung cancer risk globally (false discovery rate value < 0.15). In addition, there were positive interactions between KLK15 rs3745523 and smoky coal use (OR: 9.40; P interaction = 0.07), and between FCER2 rs7249320 and KLK2 rs2739476 (OR: 10.77; P interaction = 0.003). Our results suggest that genetic polymorphisms in innate immunity genes may play a role in the carcinogenesis of lung cancer caused by polycyclic aromatic hydrocarbon-containing coal smoke. Integrin/receptor and complement pathways as well as IgE regulation are particular noteworthy.
lung cancer; innate immunity; single nucleotide polymorphism; polycyclic aromatic hydrocarbon; coal; FERC2; KLK
Chromosomal translocations are the hallmark genetic aberration in non-Hodgkin lymphoma (NHL), with specific translocations often selectively associated with specific NHL subtypes. Because many NHL-associated translocations involve cell cycle, apoptosis, and lymphocyte development regulatory genes, we evaluated NHL risk associated with common genetic variation in 20 candidate genes in these pathways. Genotyping of 203 tag single nucleotide polymorphisms (SNPs) was conducted in 1946 NHL cases and 1808 controls pooled from three independent population-based case-control studies. We used logistic regression to compute odds ratios (OR) and 95% confidence intervals (CI) for NHL and four major NHL subtypes in relation to tag SNP genotypes and haplotypes. We observed the most striking associations for tag SNPs in the pro-apoptotic gene BCL2L11 (BIM) and BCL7A, which is involved in a rare NHL-associated translocation. Variants in BCL2L11 were strongly related to follicular lymphoma only, particularly rs3789068 (ORAG=1.41, 95%CI 1.10–1.81; ORGG=1.65, 95%CI 1.25–2.19; p-trend=0.0004). Variants in BCL7A were strongly related to diffuse large B-cell lymphoma only, particularly rs1880030 (ORAG=1.34, 95%CI 1.08–1.68; ORAA=1.60, 95%CI 1.22–2.08; p-trend=0.0004). The associations for both variants were similar in all three studies and supported by haplotype analyses. We also observed notable associations for variants in BCL6, CCND1, and MYC. Our results support the role of common genetic variation in cell cycle, apoptosis, and lymphocyte development regulatory genes in lymphomagenesis, and suggest that effects may vary by NHL subtype. Replication of our findings and further study to identify functional SNPs are warranted.
lymphoma; non-Hodgkin; polymorphism; single nucleotide; apoptosis; cell cycle
Toll-like receptors (TLRs) may influence the development of non-Hodgkin lymphoma (NHL) given their important roles in recognizing microbial pathogens and stimulating multiple immune pathways. We conducted an investigation of TLR gene variants in a pooled analysis including three population-based case–control studies of NHL (1946 cases and 1808 controls). Thirty-six tag single-nucleotide polymorphisms (SNPs) in TLR2, TLR4 and the TLR10–TLR1–TLR6 gene cluster were genotyped. Two TLR10–TLR1–TLR6 variants in moderate linkage disequilibrium were significantly associated with NHL: rs10008492 [odds ratio for CT genotype (ORCT) 1.12, 95% confidence interval (CI) 0.97–1.30; ORTT 1.40, 95% CI 1.15–1.71; Ptrend = 0.001] and rs4833103 (ORAC 0.75, 95% CI 0.64–0.88; ORAA 0.74, 95% CI 0.62–0.90; Ptrend = 0.002; Pdominant = 0.0002). Associations with these SNPs were consistent across all the three studies and did not appreciably differ by histologic subtype. We found little evidence of association between TLR2 variation and all NHL, although the rare variant rs3804100 was significantly associated with marginal zone lymphoma (MZL), both overall (ORCT/CC 1.89, 95% CI 1.27–2.81; Pdominant = 0.002) and in two of the three studies. No associations with TLR4 variants were observed. This pooled analysis provides strong evidence that variation in the TLR10–TLR1–TLR6 region is associated with NHL risk and suggests that TLR2 variants may influence susceptibility to MZL.
Although breast cancer incidence is higher in black women than in white women among women younger than 40 years, the reverse is true among those aged 40 years or older. This crossover in incidence rates between black and white ethnic groups has been well described, has not been completely understood, and has been viewed as an artifact.
To quantify this incidence rate crossover, we examined data for 440 653 women with invasive breast cancer from the National Cancer Institute’s Surveillance, Epidemiology, and End Results database from January 1, 1975, through December 31, 2004. Data on invasive female breast cancers were stratified by race, age at diagnosis, year of diagnosis, and tumor characteristics. Standard descriptive analyses were supplemented with Poisson regression models, age–period–cohort models, and two-component mixture models. All statistical tests were two-sided.
We observed qualitative (ie, crossing or reversing) interactions between age and race. That is, age-specific incidence rates overall (expressed as number of breast cancers per 100 000 woman-years) were higher among black women (15.5) than among white women (13.1) younger than 40 years (difference = 2.4, 95% confidence interval [CI] = 2.4 to 2.4), and then, age-specific rates crossed with rates higher among white women (281.3) than among black women (239.5) aged 40 years or older (difference = 41.8, 95% CI = 41.7 to 41.9). The black-to-white incidence rate crossover was observed for all tumor characteristics assessed, although the crossover occurred at earlier ages of diagnosis for low-risk tumor characteristics than for high-risk tumor characteristics. The incidence rate crossover between ethnic groups was robust (ie, reliable and reproducible) to adjustment for calendar period and birth cohort effects in age–period–cohort models (P < .001 for difference by race).
Although this ecologic study cannot determine the individual-level factors responsible for the racial crossover in vital rates, it confirms that the age-related crossover in breast cancer incidence rates between black and white ethnic groups is a robust age-specific effect that is independent of period and cohort effects.
Common genetic variation may play an important role in altering lung cancer risk. We conducted a pathway-based candidate gene evaluation to identify genetic variations that may be associated with lung cancer in a population-based case–control study in Xuan Wei, China (122 cases and 111 controls). A total of 1260 single-nucleotide polymorphisms (SNPs) in 380 candidate genes for lung cancer were successfully genotyped and assigned to one of 10 pathways based on gene ontology. Logistic regression was used to assess the marginal effect of each SNP on lung cancer susceptibility. The minP test was used to identify statistically significant associations at the gene level. Important pathways were identified using a test of proportions and the rank truncated product methods. The cell cycle pathway was found as the most important pathway (P = 0.044) with four genes significantly associated with lung cancer (PLA2G6 minP = 0.001, CCNA2 minP = 0.006, GSK3β minP = 0.007 and EGF minP = 0.013), after adjusting for multiple comparisons. Interestingly, most cell cycle genes that were associated with lung cancer in this analysis were concentrated in the AKT signaling pathway, which is essential for regulation of cell cycle progression and cellular survival, and may be important in lung cancer etiology in Xuan Wei. These results should be viewed as exploratory until they are replicated in a larger study.
In the kidney vitamin D is converted to its active form. Since vitamin D exerts its activity through binding to the nuclear vitamin D receptor (VDR), most genetic studies have primarily focused on variation within this gene. Therefore, analysis of genetic variation in VDR and other vitamin D pathway genes may provide insight into the role of vitamin D in renal cell carcinoma (RCC) etiology. RCC cases (N = 777) and controls (N = 1,035) were genotyped to investigate the relationship between RCC risk and variation in eight target genes. Minimum-p-value permutation (Min-P) tests were used to identify genes associated with risk. A three single nucleotide polymorphism (SNP) sliding window was used to identify chromosomal regions with a False Discovery Rate of <10%, where subsequently, haplotype relative risks were computed in Haplostats. Min-P values showed that VDR (p-value = 0.02) and retinoid-X-receptor-alpha (RXRA) (p-value = 0.10) were associated with RCC risk. Within VDR, three haplotypes across two chromosomal regions of interest were identified. The first region, located within intron 2, contained two haplotypes that increased RCC risk by approximately 25%. The second region included a haplotype (rs2239179, rs12717991) across intron 4 that increased risk among participants with the TC (OR = 1.31, 95% CI = 1.09–1.57) haplotype compared to participants with the common haplotype, TT. Across RXRA, one haplotype located 3′ of the coding sequence (rs748964, rs3118523), increased RCC risk 35% among individuals with the variant haplotype compared to those with the most common haplotype. This study comprehensively evaluated genetic variation across eight vitamin D pathway genes in relation to RCC risk. We found increased risk associated with VDR and RXRA. Replication studies are warranted to confirm these findings.
A promoter polymorphism in the pro-inflammatory cytokine tumor necrosis factor (TNF) (TNF G-308A) is associated with increased non-Hodgkin lymphoma (NHL) risk. The protein product, TNF-α, activates the nuclear factor kappa beta (NF-κB) transcription factor, and is critical for inflammatory and apoptotic responses in cancer progression. We hypothesized that the TNF and NF-κB pathways are important for NHL and that gene variations across the pathways may alter NHL risk.
We genotyped 500 tag single nucleotide polymorphisms (SNPs) from 48 candidate gene regions (defined as 20 kb 5′, 10 kb 3′) in the TNF and TNF receptor superfamilies and the NF-κB and related transcription factors, in 1946 NHL cases and 1808 controls pooled from three independent population-based case-control studies. We obtaineded a gene region-level summary of association by computing the minimum p-value (“minP test”). We used logistic regression to compute odds ratios and 95% confidence intervals for NHL and four major NHL subtypes in relation to SNP genotypes and haplotypes. For NHL, the tail strength statistic supported an overall relationship between the TNF/NF-κB pathway and NHL (p = 0.02). We confirmed the association between TNF/LTA on chromosome 6p21.3 with NHL and found the LTA rs2844484 SNP most significantly and specifically associated with the major subtype, diffuse large B-cell lymphoma (DLBCL) (p-trend = 0.001). We also implicated for the first time, variants in NFKBIL1 on chromosome 6p21.3, associated with NHL. Other gene regions identified as statistically significantly associated with NHL included FAS, IRF4, TNFSF13B, TANK, TNFSF7 and TNFRSF13C. Accordingly, the single most significant SNPs associated with NHL were FAS rs4934436 (p-trend = 0.0024), IRF4 rs12211228 (p-trend = 0.0026), TNFSF13B rs2582869 (p-trend = 0.0055), TANK rs1921310 (p-trend = 0.0025), TNFSF7 rs16994592 (p-trend = 0.0024), and TNFRSF13C rs6002551 (p-trend = 0.0074). All associations were consistent in each study with no apparent specificity for NHL subtype.
Our results provide consistent evidence that variation in the TNF superfamily of genes and specifically within chromosome 6p21.3 impacts lymphomagenesis. Further characterization of these susceptibility loci and identification of functional variants are warranted.
We conducted a case-control study of renal cancer (987 cases and 1298 controls) in Central and Eastern Europe and analyzed genomic DNA for 319 tagging single-nucleotide polymorphisms (SNPs) in 21 genes involved in cellular growth, differentiation and apoptosis using an Illumina Oligo Pool All (OPA). A haplotype-based method (sliding window analysis of consecutive SNPs) was used to identify chromosome regions of interest that remained significant at a false discovery rate of 10%. Subsequently, risk estimates were generated for regions with a high level of signal and individual SNPs by unconditional logistic regression adjusting for age, gender and study center. Three regions containing genes associated with renal cancer were identified: caspase 1/5/4/12(CASP 1/5/4/12), epidermal growth factor receptor (EGFR), and insulin-like growth factor binding protein-3 (IGFBP3). We observed that individuals with CASP1/5/4/12 haplotype (spanning area upstream of CASP1 through exon 2 of CASP5) GGGCTCAGT were at higher risk of renal cancer compared to individuals with the most common haplotype (OR:1.40, 95% CI:1.10–1.78, p-value = 0.007). Analysis of EGFR revealed three strong signals within intron 1, particularly a region centered around rs759158 with a global p = 0.006 (GGG: OR:1.26, 95% CI:1.04–1.53 and ATG: OR:1.55, 95% CI:1.14–2.11). A region in IGFBP3 was also associated with increased risk (global p = 0.04). In addition, the number of statistically significant (p-value<0.05) SNP associations observed within these three genes was higher than would be expected by chance on a gene level. To our knowledge, this is the first study to evaluate these genes in relation to renal cancer and there is need to replicate and extend our findings. The specific regions associated with risk may have particular relevance for gene function and/or carcinogenesis. In conclusion, our evaluation has identified common genetic variants in CASP1, CASP5, EGFR, and IGFBP3 that could be associated with renal cancer risk.
Statistical power calculations inform the design and interpretation of genetic association studies, but few programs are tailored to case-control studies of single nucleotide polymorphisms (SNPs) in unrelated subjects.
We have developed the "Power for Genetic Association analyses" (PGA) package which comprises algorithms and graphical user interfaces for sample size and minimum detectable risk calculations using SNP or haplotype effects under different genetic models and study constrains. The software accounts for linkage disequilibrium and statistical multiple comparisons. The results are presented in graphs or tables and can be printed or exported in standard file formats.
PGA is user friendly software that can facilitate decision making for association studies of candidate genes, fine-mapping studies, and whole-genome scans. Stand-alone executable files and a Matlab toolbox are available for download at:
The genetic basis of odorant-specific variations in human olfactory thresholds, and in particular of enhanced odorant sensitivity (hyperosmia), remains largely unknown. Olfactory receptor (OR) segregating pseudogenes, displaying both functional and nonfunctional alleles in humans, are excellent candidates to underlie these differences in olfactory sensitivity. To explore this hypothesis, we examined the association between olfactory detection threshold phenotypes of four odorants and segregating pseudogene genotypes of 43 ORs genome-wide. A strong association signal was observed between the single nucleotide polymorphism variants in OR11H7P and sensitivity to the odorant isovaleric acid. This association was largely due to the low frequency of homozygous pseudogenized genotype in individuals with specific hyperosmia to this odorant, implying a possible functional role of OR11H7P in isovaleric acid detection. This predicted receptor–ligand functional relationship was further verified using the Xenopus oocyte expression system, whereby the intact allele of OR11H7P exhibited a response to isovaleric acid. Notably, we also uncovered another mechanism affecting general olfactory acuity that manifested as a significant inter-odorant threshold concordance, resulting in an overrepresentation of individuals who were hyperosmic to several odorants. An involvement of polymorphisms in other downstream transduction genes is one possible explanation for this observation. Thus, human hyperosmia to isovaleric acid is a complex trait, contributed to by both receptor and other mechanisms in the olfactory signaling pathway.
Humans can accurately discern thousands of odors, yet there is considerable inter-individual variation in the ability to detect different odors, with individuals exhibiting low sensitivity (hyposmia), high sensitivity (hyperosmia), or even “blindness” (anosmia) to particular odors. Such differences are thought to stem from genetic differences in olfactory receptor (OR) genes, which encode proteins that initiate olfactory signaling. OR segregating pseudogenes, which have both functional and inactive alleles in the population, are excellent candidates for producing this olfactory phenotype diversity. Here, we provide evidence that a particular segregating OR gene is related to sensitivity to a sweaty odorant, isovaleric acid. We show that hypersensitivity towards this odorant is seen predominantly in individuals who carry at least one copy of the intact allele. Furthermore, we demonstrate that this hyperosmia is a complex trait, being driven by additional factors affecting general olfactory acuity. Our results highlight a functional role of segregating pseudogenes in human olfactory variability, and constitute a step towards deciphering the genetic basis of human olfactory variability.
Genetic epidemiology analysis reveals a multifaceted mechanism underlying enhanced olfactory sensitivity to the sweaty odor of isovaleric acid in humans.
Olfactory receptors (ORs), the largest mammalian gene superfamily (900–1400 genes), has >50% pseudogenes in humans. While most of these inactive genes are identified via coding frame (nonsense) disruptions, seemingly intact genes may also be inactive due to other deleterious (missense) mutations. An ultimate assessment of the actual size of the functional human OR repertoire thus requires an accurate distinction between genes and pseudogenes.
To characterize inactive ORs with intact open reading frame, we have developed a probabilistic Classifier for Olfactory Receptor Pseudogenes (CORP). This algorithm is based on deviations from a functionally crucial consensus, constituting sixty highly conserved positions identified by a comparison of two evolutionarily-constrained OR repertoires (mouse and dog) with a small pseudogene fraction. We used a logistic regression analysis to assign appropriate coefficients to the conserved position and thus achieving maximal separation between active and inactive ORs. Consequently, the algorithms identified only 5% of the mouse functional ORs as pseudogenes, setting an upper limit of 0.05 to the false positive detection. Finally we used this algorithm to classify the 384 purportedly intact human OR genes. Of these, 135 were predicted as likely encoding non-functional proteins, and 38 were segregating between active and inactive forms due to missense polymorphisms.
We demonstrated that the CORP algorithm is capable to distinguish between functional and non-functional OR genes with high precision even when the encoded protein would differ by a single amino acid. Using the CORP algorithm, we predict that ~70% of human OR genes are likely non-functional pseudogenes, a much higher number than hitherto suspected. The method we present may be employed for better annotation of inactive members in other gene families as well.
CORP algorithm is available at: