The oral microbiome in relation to pancreatic cancer risk in African Americans.

BACKGROUND: African Americans have the highest pancreatic cancer incidence of any racial/ethnic group in the United States. The oral microbiome was associated with pancreatic cancer risk in a recent study, but no such studies have been conducted in African Americans. Poor oral health, which can be a cause or effect of microbial populations, was associated with an increased risk of pancreatic cancer in a single study of African Americans. METHODS: We prospectively investigated the oral microbiome in relation to pancreatic cancer risk among 122 African-American pancreatic cancer cases and 354 controls. DNA was extracted from oral wash samples for metagenomic shotgun sequencing. Alpha and beta diversity of the microbial profiles were calculated. Multivariable conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between microbes and pancreatic cancer risk. RESULTS: No associations were observed with alpha or beta diversity, and no individual microbial taxa were differentially abundant between cases and control, after accounting for multiple comparisons. Among never smokers, there were elevated ORs for known oral pathogens: Porphyromonas gingivalis (OR = 1.69, 95% CI: 0.80-3.56), Prevotella intermedia (OR = 1.40, 95% CI: 0.69-2.85), and Tannerella forsythia (OR = 1.36, 95% CI: 0.66-2.77). CONCLUSIONS: Previously reported associations between oral taxa and pancreatic cancer were not present in this African-American population overall.

Socioenvironmental adversity and risk of prostate cancer in non-Hispanic black and white men.

Non-Hispanic black (NHB) men experience higher risk of prostate cancer than other racial/ethnic groups, and it is possible that socioenvironmental (SE) adversity and resulting stress may contribute to this disparity. Data from the Southern Community Cohort Study were used to evaluate associations between SE adversity and perceived stress in relation to prostate cancer risk, overall and by race/ethnicity and grade. Between 2002 and 2009, 26,741 men completed a questionnaire, from which an 8-item SE adversity composite was created (covering socioeconomic status, residential environment, and social support/buffers). Two items from the Perceived Stress Scale were assessed. With follow-up through 2011, 527 prostate cancer cases were diagnosed. In multivariable models, each one-unit increase in the SE adversity composite was associated with increased prostate cancer risk among non-Hispanic white (NHW) men (HR 1.23; 95% CI 1.02-1.48) and reduced risk among NHB men (HR 0.89; 95% CI 0.82-0.95) (p interaction: 0.001). This pattern held for low grade, but not high grade, cancers although power was limited for the latter. Perceived stress variables were associated with increased risk of prostate cancer among NHW men, but not among NHB men. Results do not support the hypothesis that SE adversity my underlay the racial disparity in prostate cancer, over and above that of covariates, including healthcare utilization.

Novel colon cancer susceptibility variants identified from a genome-wide association study in African Americans.

Genome-wide association studies (GWAS) in ethnic/racial minority populations can help to fine-map previously identified risk regions or discover new risk loci because of the genetic diversity in these populations. We conducted a GWAS of colorectal cancer (CRC) in 6,597 African Americans (1,894 cases and 4,703 controls) (Stage 1) and followed up the most promising markers in a replication set of 2,041 participants of African descent (891 cases and 1,150 controls) (Stage 2). We identified a novel variant, rs56848936 in the gene SYMPK at 19q13.3, associated with colon cancer risk (odds ratio 0.61 for the risk allele G, p = 2.4 × 10-8 ). The frequency of the G allele was 0.06 in African Americans, compared to <0.01 in Europeans, Asians and Amerindians in the 1000 Genomes project. In addition, a variant previously identified through fine-mapping in this GWAS in the region 19q13.1, rs7252505, was confirmed to be more strongly associated with CRC in the African American replication set than the variant originally reported in Europeans (rs10411210). The association between rs7252505 and CRC was of borderline significance (p = 0.05) in a Hispanic population GWAS with 1,611 CRC cases and 4,330 controls. With the three datasets combined, the odds ratio was 0.84 for the risk allele A (95% confidence interval 0.79-0.89, p = 3.7 × 10-8 ). This study further highlights the importance of conducting GWAS studies in diverse ancestry populations.

Genome-wide scan of 29,141 African Americans finds no evidence of directional selection since admixture.

The extent of recent selection in admixed populations is currently an unresolved question. We scanned the genomes of 29,141 African Americans and failed to find any genome-wide-significant deviations in local ancestry, indicating no evidence of selection influencing ancestry after admixture. A recent analysis of data from 1,890 African Americans reported that there was evidence of selection in African Americans after their ancestors left Africa, both before and after admixture. Selection after admixture was reported on the basis of deviations in local ancestry, and selection before admixture was reported on the basis of allele-frequency differences between African Americans and African populations. The local-ancestry deviations reported by the previous study did not replicate in our very large sample, and we show that such deviations were expected purely by chance, given the number of hypotheses tested. We further show that the previous study's conclusion of selection in African Americans before admixture is also subject to doubt. This is because the FST statistics they used were inflated and because true signals of unusual allele-frequency differences between African Americans and African populations would be best explained by selection that occurred in Africa prior to migration to the Americas.

Fine-mapping the HOXB region detects common variants tagging a rare coding allele: evidence for synthetic association in prostate cancer.

The HOXB13 gene has been implicated in prostate cancer (PrCa) susceptibility. We performed a high resolution fine-mapping analysis to comprehensively evaluate the association between common genetic variation across the HOXB genetic locus at 17q21 and PrCa risk. This involved genotyping 700 SNPs using a custom Illumina iSelect array (iCOGS) followed by imputation of 3195 SNPs in 20,440 PrCa cases and 21,469 controls in The PRACTICAL consortium. We identified a cluster of highly correlated common variants situated within or closely upstream of HOXB13 that were significantly associated with PrCa risk, described by rs117576373 (OR 1.30, P = 2.62×10(-14)). Additional genotyping, conditional regression and haplotype analyses indicated that the newly identified common variants tag a rare, partially correlated coding variant in the HOXB13 gene (G84E, rs138213197), which has been identified recently as a moderate penetrance PrCa susceptibility allele. The potential for GWAS associations detected through common SNPs to be driven by rare causal variants with higher relative risks has long been proposed; however, to our knowledge this is the first experimental evidence for this phenomenon of synthetic association contributing to cancer susceptibility.

Adolescent body mass index and erythrocyte sedimentation rate in relation to colorectal cancer risk.

OBJECTIVE: Adult obesity and inflammation have been associated with risk of colorectal cancer (CRC); however, less is known about how adolescent body mass index (BMI) and inflammation, as measured by erythrocyte sedimentation rate (ESR), relate to CRC risk. We sought to evaluate these associations in a cohort of 239 658 Swedish men who underwent compulsory military enlistment examinations in late adolescence (ages 16-20 years). DESIGN: At the time of the conscription assessment (1969-1976), height and weight were measured and ESR was assayed. By linkage to the national cancer registry, these conscripts were followed for CRC through 1 January 2010. Over an average of 35 years of follow-up, 885 cases of CRC occurred, including 501 colon cancers and 384 rectal cancers. Cox regression was used to estimate adjusted HRs and corresponding 95% CIs. RESULTS: Compared with normal weight (BMI 18.5 to <25 kg/m(2)) in late adolescence, upper overweight (BMI 27.5 to <30 kg/m(2)) was associated with a 2.08-fold higher risk of CRC (95% CI 1.40 to 3.07) and obesity (BMI 30+ kg/m(2)) was associated with a 2.38-fold higher risk of CRC (95% CI 1.51 to 3.76) (p-trend: <0.001). Male adolescents with ESR (15+ mm/h) had a 63% higher risk of CRC (HR 1.63; 95% CI 1.08 to 2.45) than those with low ESR (<10 mm/h) (p-trend: 0.006). Associations did not significantly differ by anatomic site. CONCLUSIONS: Late-adolescent BMI and inflammation, as measured by ESR, may be independently associated with future CRC risk. Further research is needed to better understand how early-life exposures relate to CRC.

Use of glucosamine and chondroitin supplements in relation to risk of colorectal cancer: Results from the Nurses' Health Study and Health Professionals follow-up study.

Recent epidemiologic evidence has emerged to suggest that use of glucosamine and chondroitin supplements may be associated with reduced risk of colorectal cancer (CRC). We therefore evaluated the association between use of these non-vitamin, non-mineral supplements and risk of CRC in two prospective cohorts, the Nurses' Health Study and Health Professionals Follow-up Study. Regular use of glucosamine and chondroitin was first assessed in 2002 and participants were followed until 2010, over which time 672 CRC cases occurred. Cox proportional hazards regression was used to estimate relative risks (RRs) within each cohort, and results were pooled using a random effects meta-analysis. Associations were comparable across cohorts, with a RR of 0.79 (95% CI: 0.63-1.00) observed for any use of glucosamine and a RR of 0.77 (95% CI: 0.59-1.01) observed for any use of chondroitin. Use of glucosamine in the absence of chondroitin was not associated with risk of CRC, whereas use of glucosamine + chondroitin was significantly associated with risk (RR: 0.77; 95% CI: 0.58-0.999). The association between use of glucosamine + chondroitin and risk of CRC did not change markedly when accounting for change in exposure status over follow-up (RR: 0.75; 95% CI: 0.58-0.96), nor did the association significantly vary by sex, aspirin use, body mass index, or physical activity. The association was comparable for cancers of the colon and rectum. Results support a protective association between use of glucosamine and chondroitin and risk of CRC. Further study is needed to better understand the chemopreventive potential of these supplements.

Generalizability of established prostate cancer risk variants in men of African ancestry.

Genome-wide association studies have identified more than 80 risk variants for prostate cancer, mainly in European or Asian populations. The generalizability of these variants in other racial/ethnic populations needs to be understood before the loci can be used widely in risk modeling. In our study, we examined 82 previously reported risk variants in 4,853 prostate cancer cases and 4,678 controls of African ancestry. We performed association testing for each variant using logistic regression adjusted for age, study and global ancestry. Of the 82 known risk variants, 68 (83%) had effects that were directionally consistent in their association with prostate cancer risk and 30 (37%) were significantly associated with risk at p < 0.05, with the most statistically significant variants being rs116041037 (p = 3.7 × 10(-26) ) and rs6983561 (p = 1.1 × 10(-16) ) at 8q24, as well as rs7210100 (p = 5.4 × 10(-8) ) at 17q21. By exploring each locus in search of better markers, the number of variants that captured risk in men of African ancestry (p < 0.05) increased from 30 (37%) to 44 (54%). An aggregate score comprised of these 44 markers was strongly associated with prostate cancer risk [per-allele odds ratio (OR) = 1.12, p = 7.3 × 10(-98) ]. In summary, the consistent directions of effects for the vast majority of variants in men of African ancestry indicate common functional alleles that are shared across populations. Further exploration of these susceptibility loci is needed to identify the underlying biologically relevant variants to improve prostate cancer risk modeling in populations of African ancestry.

Healthy Eating and Risks of Total and Cause-Specific Death among Low-Income Populations of African-Americans and Other Adults in the Southeastern United States: A Prospective Cohort Study.

BACKGROUND: A healthy diet, as defined by the US Dietary Guidelines for Americans (DGA), has been associated with lower morbidity and mortality from major chronic diseases in studies conducted in predominantly non-Hispanic white individuals. It is unknown whether this association can be extrapolated to African-Americans and low-income populations. METHODS AND FINDINGS: We examined the associations of adherence to the DGA with total and cause-specific mortality in the Southern Community Cohort Study, a prospective study that recruited 84,735 American adults, aged 40-79 y, from 12 southeastern US states during 2002-2009, mostly through community health centers that serve low-income populations. The present analysis included 50,434 African-Americans, 24,054 white individuals, and 3,084 individuals of other racial/ethnic groups, among whom 42,759 participants had an annual household income less than US$15,000. Usual dietary intakes were assessed using a validated food frequency questionnaire at baseline. Adherence to the DGA was measured by the Healthy Eating Index (HEI), 2010 and 2005 editions (HEI-2010 and HEI-2005, respectively). During a mean follow-up of 6.2 y, 6,906 deaths were identified, including 2,244 from cardiovascular disease, 1,794 from cancer, and 2,550 from other diseases. A higher HEI-2010 score was associated with lower risks of disease death, with adjusted hazard ratios (HRs) of 0.80 (95% CI, 0.73-0.86) for all-disease mortality, 0.81 (95% CI, 0.70-0.94) for cardiovascular disease mortality, 0.81 (95% CI, 0.69-0.95) for cancer mortality, and 0.77 (95% CI, 0.67-0.88) for other disease mortality, when comparing the highest quintile with the lowest (all p-values for trend < 0.05). Similar inverse associations between HEI-2010 score and mortality were observed regardless of sex, race, and income (all p-values for interaction > 0.50). Several component scores in the HEI-2010, including whole grains, dairy, seafood and plant proteins, and ratio of unsaturated to saturated fatty acids, showed significant inverse associations with total mortality. HEI-2005 score was also associated with lower disease mortality, with a HR of 0.86 (95% CI, 0.79-0.93) when comparing extreme quintiles. Given the observational study design, however, residual confounding cannot be completely ruled out. In addition, future studies are needed to evaluate the generalizability of these findings to African-Americans of other socioeconomic status. CONCLUSIONS: Our results showed, to our knowledge for the first time, that adherence to the DGA was associated with lower total and cause-specific mortality in a low-income population, including a large proportion of African-Americans, living in the southeastern US.

Body mass index in young adulthood, obesity trajectory, and premature mortality.

Although much research has been conducted on the role adult body mass index (BMI) plays in mortality, there have been fewer studies that evaluated the associations of BMI in young adulthood and adult weight trajectory with mortality, and it remains uncertain whether associations differ by race or sex. We prospectively examined the relationships of BMI in young adulthood (21 years of age) and adult obesity trajectory with later-life mortality rates among 75,881 men and women in the Southern Community Cohort Study. Study participants were enrolled between 2002 and 2009 at ages 40-79 years and were followed through December, 2011. Multivariable Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals. There were 7,301 deaths in the 474,970 person-years of follow-up. Participants who reported being overweight or obese as young adults had mortality rates that were 19% (95% confidence interval: 12, 27) and 64% (95% confidence interval: 52, 78) higher, respectively, than those of their normal weight counterparts. The results did not significantly differ by race or sex. Participants who reported being obese in young adulthood only or in both young and middle adulthood experienced mortality rates that were 40%-90% higher than those of participants who were nonobese at either time. These results suggest that obesity in young adulthood is associated with higher mortality risk regardless of race, sex, and obesity status in later life.

Fine-mapping of genome-wide association study-identified risk loci for colorectal cancer in African Americans.

Genome-wide association studies of colorectal cancer (CRC) in Europeans and Asians have identified 21 risk susceptibility regions [29 index single-nucleotide polymorphisms (SNPs)]. Characterizing these risk regions in diverse racial groups with different linkage disequilibrium (LD) structure can help localize causal variants. We examined associations between CRC and all 29 index SNPs in 6597 African Americans (1894 cases and 4703 controls). Nine SNPs in eight regions (5q31.1, 6q26-q27, 8q23.3, 8q24.21, 11q13.4, 15q13.3, 18q21.1 and 20p12.3) formally replicated in our data with one-sided P-values <0.05 and the same risk directions as reported previously. We performed fine-mapping of the 21 risk regions (including 250 kb on both sides of the index SNPs) using genotyped and imputed markers at the density of the 1000 Genomes Project to search for additional or more predictive risk markers. Among the SNPs correlated with the index variants, two markers, rs12759486 (or rs7547751, a putative functional variant in perfect LD with it) in 1q41 and rs7252505 in 19q13.1, were more strongly and statistically significantly associated with CRC (P < 0.0006). The average per allele risk was improved using the replicated index variants and the two new markers (odds ratio = 1.14, P = 6.5 × 10(-16)) in African Americans, compared with using all index SNPs (odds ratio = 1.07, P = 3.4 × 10(-10)). The contribution of the two new risk SNPs to CRC heritability was estimated to be 1.5% in African Americans. This study highlights the importance of fine-mapping in diverse populations.

Fine-mapping identifies multiple prostate cancer risk loci at 5p15, one of which associates with TERT expression.

Associations between single nucleotide polymorphisms (SNPs) at 5p15 and multiple cancer types have been reported. We have previously shown evidence for a strong association between prostate cancer (PrCa) risk and rs2242652 at 5p15, intronic in the telomerase reverse transcriptase (TERT) gene that encodes TERT. To comprehensively evaluate the association between genetic variation across this region and PrCa, we performed a fine-mapping analysis by genotyping 134 SNPs using a custom Illumina iSelect array or Sequenom MassArray iPlex, followed by imputation of 1094 SNPs in 22 301 PrCa cases and 22 320 controls in The PRACTICAL consortium. Multiple stepwise logistic regression analysis identified four signals in the promoter or intronic regions of TERT that independently associated with PrCa risk. Gene expression analysis of normal prostate tissue showed evidence that SNPs within one of these regions also associated with TERT expression, providing a potential mechanism for predisposition to disease.

Statin use and risk of prostate cancer: Results from the Southern Community Cohort Study.

BACKGROUND: Epidemiologic studies suggest that statin use may be inversely associated with risk of prostate cancer, but prior studies have focused predominantly on non-Hispanic white populations. METHODS: We evaluated the association between statin use and prostate cancer risk in the Southern Community Cohort Study (SCCS). Study participants were 32,091 men aged 40-79 at baseline, 67% of whom were non-Hispanic black. Between study enrollment (2002-2009) and December 31, 2010, 570 prostate cancer cases were diagnosed, including 324 low-grade cancers (Gleason score <7 or Gleason pattern 3 + 4) and 107 high-grade cancers (Gleason score >7 or Gleason pattern 4 + 3). Analyses of overall prostate cancer were conducted using Cox regression and analyses of grade-specific cancer were conducted using competing risks models. RESULTS: Ten percent of non-Hispanic black men and 22% of non-Hispanic white men reported use of statins at study enrollment. As compared to non-use, statin use was associated with a non-significant 14% lower risk of prostate cancer in multivariable models (Hazard Ratio [HR]:0.86; 95% Confidence Interval [CI]: 0.63-1.18). This association was stronger for high-grade cancer (HR: 0.62; 95%CI: 0.30, 1.28) than low-grade cancer (HR:0.98; 95%CI: 0.65-1.48). Results were similar by race/ethnicity (p-interaction: 0.41) and did not vary by history of prostate-specific antigen [PSA] screening (p-interaction: 0.65). CONCLUSIONS: Results suggest no strong association between statin use and prostate cancer risk overall, and further suggest that if a modest protective effect does exist, it does not vary by race/ethnicity and may be restricted to high-grade tumors, although power to detect differences by subgroup was limited.

Persistence of Trichomonas vaginalis serostatus in men over time.

PURPOSE: Previous epidemiologic studies have observed positive associations between Trichomonas vaginalis (Tv) serostatus and both prostate cancer (PCa) risk and mortality. However, only a few small older studies have examined Tv antibody persistence over time, all of which were composed mainly of female patients. Therefore, we examined Tv antibody persistence over time, as well as intra-individual variability, among middle- to older-aged men in the Southern Community Cohort Study (SCCS). METHODS: We tested baseline and repeat plasma specimens (collected 1-3 years later) from 248 male participants for Tv antibodies. We used the same enzyme-linked immunosorbent assay as in previous studies of Tv serostatus and PCa. RESULTS: At baseline, 46 (18.5 %) participants were seropositive for Tv infection. Seventy-six percent of these men were still seropositive 1-3 years later. A similar proportion of men "seroconverted" (4.0 %) as "seroreverted" (4.4 %), all of whom had absorbance values near the cutoff point for seropositivity. Overall, substantial agreement was observed between baseline and repeat serostatus (κ = 0.72, 95 % confidence interval 0.60-0.83). CONCLUSION: Tv seropositivity was largely persistent between plasma specimens collected 1-3 years apart from middle- to older-aged men. These high levels of persistence are similar to those observed for other sexually transmitted infections frequently investigated in relation to PCa.

Risk factors for endometrial cancer in black and white women: a pooled analysis from the Epidemiology of Endometrial Cancer Consortium (E2C2).

PURPOSE: Endometrial cancer (EC) is the most common gynecologic cancer in the USA. Over the last decade, the incidence rate has been increasing, with a larger increase among blacks. The aim of this study was to compare risk factors for EC in black and white women. METHODS: Data from seven cohort and four case-control studies were pooled. Unconditional logistic regression was used to estimate adjusted odds ratios (OR) and 95 % confidence intervals for each risk factor in blacks and whites separately. RESULTS: Data were pooled for 2,011 black women (516 cases and 1,495 controls) and 19,297 white women (5,693 cases and 13,604 controls). BMI ≥ 30 was associated with an approximate threefold increase in risk of EC in both black and white women (ORblack 2.93, 95 % CI 2.11, 4.07 and ORwhite 2.99, 95 % CI 2.74, 3.26). Diabetes was associated with a 30-40 % increase in risk among both groups. Increasing parity was associated with decreasing risk of EC in blacks and whites (p value = 0.02 and <0.001, respectively). Current and former smoking was associated with decreased risk of EC among all women. Both black and white women who used oral contraceptives for 10 +years were also at reduced risk of EC (OR 0.49, 95 % CI 0.27, 0.88 and OR 0.69, 95 % CI 0.58, 0.83, respectively). Previous history of hypertension was not associated with EC risk in either group. CONCLUSIONS: The major known risk factors for EC exert similar effects on black and white women. Differences in the incidence rates between the two populations may be due to differences in the prevalence of risk factors.

Physical activity, sedentary behavior, and cause-specific mortality in black and white adults in the Southern Community Cohort Study.

There is limited evidence demonstrating the benefits of physical activity with regard to mortality risk or the harms associated with sedentary behavior in black adults, so we examined the relationships between these health behaviors and cause-specific mortality in a prospective study that had a large proportion of black adults. Participants (40-79 years of age) enrolled in the Southern Community Cohort Study between 2002 and 2009 (n = 63,308) were prospectively followed over 6.4 years, and 3,613 and 1,394 deaths occurred in blacks and whites, respectively. Black adults who reported the highest overall physical activity level (≥32.3 metabolic equivalent-hours/day vs. <9.7 metabolic equivalent-hours/day) had lower risks of death from all causes (hazard ratio (HR) = 0.76. 95% confidence interval (CI): 0.69, 0.85), cardiovascular disease (HR = 0.81, 95% CI: 0.67, 0.98), and cancer (HR = 0.76, 95% CI: 0.62, 0.94). In whites, a higher physical activity level was associated with a lower risk of death from all causes (HR = 0.76, 95% CI: 0.64, 0.90) and cardiovascular disease (HR = 0.69, 95% CI: 0.49, 0.99) but not cancer (HR = 0.95, 95% CI: 0.67, 1.34). Spending more time being sedentary (>12 hours/day vs. <5.76 hours/day) was associated with a 20%-25% increased risk of all-cause mortality in blacks and whites. Blacks who reported the most time spent being sedentary (≥10.5 hours/day) and lowest level of physical activity (<12.6 metabolic equivalent-hours/day) had a greater risk of death (HR = 1.47, 95% CI: 1.25, 1.71). Our study provides evidence that suggests that health promotion efforts to increase physical activity level and decrease sedentary time could help reduce mortality risk in black adults.

Socioeconomic status, race, and mortality: a prospective cohort study.

OBJECTIVES: We evaluated the independent and joint effects of race, individual socioeconomic status (SES), and neighborhood SES on mortality risk. METHODS: We conducted a prospective analysis involving 52 965 non-Hispanic Black and 23 592 non-Hispanic White adults taking part in the Southern Community Cohort Study. Cox proportional hazards modeling was used to determine associations of race and SES with all-cause and cause-specific mortality. RESULTS: In our cohort, wherein Blacks and Whites had similar individual SES, Blacks were less likely than Whites to die during the follow-up period (hazard ratio [HR] = 0.78; 95% confidence interval [CI] = 0.73, 0.84). Low household income was a strong predictor of all-cause mortality among both Blacks and Whites (HR = 1.76; 95% CI = 1.45, 2.12). Being in the lowest (vs highest) category with respect to both individual and neighborhood SES was associated with a nearly 3-fold increase in all-cause mortality risk (HR = 2.76; 95% CI = 1.99, 3.84). There was no significant mortality-related interaction between individual SES and neighborhood SES among either Blacks or Whites. CONCLUSIONS: SES is a strong predictor of premature mortality, and the independent associations of individual SES and neighborhood SES with mortality risk are similar for Blacks and Whites.

Characterizing genetic risk at known prostate cancer susceptibility loci in African Americans.

GWAS of prostate cancer have been remarkably successful in revealing common genetic variants and novel biological pathways that are linked with its etiology. A more complete understanding of inherited susceptibility to prostate cancer in the general population will come from continuing such discovery efforts and from testing known risk alleles in diverse racial and ethnic groups. In this large study of prostate cancer in African American men (3,425 prostate cancer cases and 3,290 controls), we tested 49 risk variants located in 28 genomic regions identified through GWAS in men of European and Asian descent, and we replicated associations (at p≤0.05) with roughly half of these markers. Through fine-mapping, we identified nearby markers in many regions that better define associations in African Americans. At 8q24, we found 9 variants (p≤6×10(-4)) that best capture risk of prostate cancer in African Americans, many of which are more common in men of African than European descent. The markers found to be associated with risk at each locus improved risk modeling in African Americans (per allele OR = 1.17) over the alleles reported in the original GWAS (OR = 1.08). In summary, in this detailed analysis of the prostate cancer risk loci reported from GWAS, we have validated and improved upon markers of risk in some regions that better define the association with prostate cancer in African Americans. Our findings with variants at 8q24 also reinforce the importance of this region as a major risk locus for prostate cancer in men of African ancestry.

A prospective study of serum 25-hydroxyvitamin d levels and mortality among African Americans and non-African Americans.

The beneficial biologic effects attributed to vitamin D suggest a potential to influence overall mortality. Evidence addressing this hypothesis is limited, especially for African Americans who have a high prevalence of vitamin D insufficiency. The authors conducted a nested case-control study within the prospective Southern Community Cohort Study to relate baseline serum levels of 25-hydroxyvitamin D (25(OH)D) with subsequent mortality. Cases were 1,852 participants who enrolled from 2002 to 2009 and died >12 months postenrollment. Controls (n = 1,852) were matched on race, sex, age, enrollment site, and blood collection date. The odds ratios for quartile 1 (<10.18 ng/mL) versus quartile 4 (>21.64 ng/mL) levels of 25(OH)D were 1.60 (95% confidence interval (CI): 1.20, 2.14) for African Americans and 2.11 (95% CI: 1.39, 3.21) for non-African Americans. The effects were strongest for circulatory disease death, where quartile 1 versus quartile 4 odds ratios were 2.53 (95% CI: 1.44, 4.46) and 3.25 (95% CI: 1.33, 7.93) for African Americans and non-African Americans, respectively. The estimated odds of total mortality were minimized in the 25(OH)D range of 35-40 ng/mL. These findings provide support for the hypothesis that vitamin D status may have an important influence on mortality for both African Americans and non-African Americans.

A small number of candidate gene SNPs reveal continental ancestry in African Americans.

Using genetic data from an obesity candidate gene study of self-reported African Americans and European Americans, we investigated the number of Ancestry Informative Markers (AIMs) and candidate gene SNPs necessary to infer continental ancestry. Proportions of African and European ancestry were assessed with STRUCTURE (K = 2), using 276 AIMs. These reference values were compared to estimates derived using 120, 60, 30, and 15 SNP subsets randomly chosen from the 276 AIMs and from 1144 SNPs in 44 candidate genes. All subsets generated estimates of ancestry consistent with the reference estimates, with mean correlations greater than 0.99 for all subsets of AIMs, and mean correlations of 0.99 ± 0.003; 0.98 ± 0.01; 0.93 ± 0.03; and 0.81 ± 0.11 for subsets of 120, 60, 30, and 15 candidate gene SNPs, respectively. Among African Americans, the median absolute difference from reference African ancestry values ranged from 0.01 to 0.03 for the four AIMs subsets and from 0.03 to 0.09 for the four candidate gene SNP subsets. Furthermore, YRI/CEU Fst values provided a metric to predict the performance of candidate gene SNPs. Our results demonstrate that a small number of SNPs randomly selected from candidate genes can be used to estimate admixture proportions in African Americans reliably.