Trans-ancestry genome-wide association meta-analysis of prostate cancer identifies new susceptibility loci and informs genetic risk prediction.

Prostate cancer is a highly heritable disease with large disparities in incidence rates across ancestry populations. We conducted a multiancestry meta-analysis of prostate cancer genome-wide association studies (107,247 cases and 127,006 controls) and identified 86 new genetic risk variants independently associated with prostate cancer risk, bringing the total to 269 known risk variants. The top genetic risk score (GRS) decile was associated with odds ratios that ranged from 5.06 (95% confidence interval (CI), 4.84-5.29) for men of European ancestry to 3.74 (95% CI, 3.36-4.17) for men of African ancestry. Men of African ancestry were estimated to have a mean GRS that was 2.18-times higher (95% CI, 2.14-2.22), and men of East Asian ancestry 0.73-times lower (95% CI, 0.71-0.76), than men of European ancestry. These findings support the role of germline variation contributing to population differences in prostate cancer risk, with the GRS offering an approach for personalized risk prediction.

Polygenic hazard score to guide screening for aggressive prostate cancer: development and validation in large scale cohorts.

OBJECTIVES: To develop and validate a genetic tool to predict age of onset of aggressive prostate cancer (PCa) and to guide decisions of who to screen and at what age. DESIGN: Analysis of genotype, PCa status, and age to select single nucleotide polymorphisms (SNPs) associated with diagnosis. These polymorphisms were incorporated into a survival analysis to estimate their effects on age at diagnosis of aggressive PCa (that is, not eligible for surveillance according to National Comprehensive Cancer Network guidelines; any of Gleason score ≥7, stage T3-T4, PSA (prostate specific antigen) concentration ≥10 ng/L, nodal metastasis, distant metastasis). The resulting polygenic hazard score is an assessment of individual genetic risk. The final model was applied to an independent dataset containing genotype and PSA screening data. The hazard score was calculated for these men to test prediction of survival free from PCa. SETTING: Multiple institutions that were members of international PRACTICAL consortium. PARTICIPANTS: All consortium participants of European ancestry with known age, PCa status, and quality assured custom (iCOGS) array genotype data. The development dataset comprised 31 747 men; the validation dataset comprised 6411 men. MAIN OUTCOME MEASURES: Prediction with hazard score of age of onset of aggressive cancer in validation set. RESULTS: In the independent validation set, the hazard score calculated from 54 single nucleotide polymorphisms was a highly significant predictor of age at diagnosis of aggressive cancer (z=11.2, P<10-16). When men in the validation set with high scores (>98th centile) were compared with those with average scores (30th-70th centile), the hazard ratio for aggressive cancer was 2.9 (95% confidence interval 2.4 to 3.4). Inclusion of family history in a combined model did not improve prediction of onset of aggressive PCa (P=0.59), and polygenic hazard score performance remained high when family history was accounted for. Additionally, the positive predictive value of PSA screening for aggressive PCa was increased with increasing polygenic hazard score. CONCLUSIONS: Polygenic hazard scores can be used for personalised genetic risk estimates that can predict for age at onset of aggressive PCa.

Risk Analysis of Prostate Cancer in PRACTICAL, a Multinational Consortium, Using 25 Known Prostate Cancer Susceptibility Loci.

BACKGROUND: Genome-wide association studies have identified multiple genetic variants associated with prostate cancer risk which explain a substantial proportion of familial relative risk. These variants can be used to stratify individuals by their risk of prostate cancer. METHODS: We genotyped 25 prostate cancer susceptibility loci in 40,414 individuals and derived a polygenic risk score (PRS). We estimated empirical odds ratios (OR) for prostate cancer associated with different risk strata defined by PRS and derived age-specific absolute risks of developing prostate cancer by PRS stratum and family history. RESULTS: The prostate cancer risk for men in the top 1% of the PRS distribution was 30.6 (95% CI, 16.4-57.3) fold compared with men in the bottom 1%, and 4.2 (95% CI, 3.2-5.5) fold compared with the median risk. The absolute risk of prostate cancer by age of 85 years was 65.8% for a man with family history in the top 1% of the PRS distribution, compared with 3.7% for a man in the bottom 1%. The PRS was only weakly correlated with serum PSA level (correlation = 0.09). CONCLUSIONS: Risk profiling can identify men at substantially increased or reduced risk of prostate cancer. The effect size, measured by OR per unit PRS, was higher in men at younger ages and in men with family history of prostate cancer. Incorporating additional newly identified loci into a PRS should improve the predictive value of risk profiles. IMPACT: We demonstrate that the risk profiling based on SNPs can identify men at substantially increased or reduced risk that could have useful implications for targeted prevention and screening programs.

CHEK2 (∗) 1100delC Mutation and Risk of Prostate Cancer.

Although the causes of prostate cancer are largely unknown, previous studies support the role of genetic factors in the development of prostate cancer. CHEK2 plays a critical role in DNA replication by responding to double-stranded breaks. In this review, we provide an overview of the current knowledge of the role of a genetic variant, 1100delC, of CHEK2 on prostate cancer risk and discuss the implication for potential translation of this knowledge into clinical practice. Currently, twelve articles that discussed CHEK2 (∗)1100delC and its association with prostate cancer were identified. Of the twelve prostate cancer studies, five studies had independent data to draw conclusive evidence from. The pooled results of OR and 95% CI were 1.98 (1.23-3.18) for unselected cases and 3.39 (1.78-6.47) for familial cases, indicating that CHEK2 (∗)1100delC mutation is associated with increased risk of prostate cancer. Screening for CHEK2(∗)1100delC should be considered in men with a familial history of prostate cancer.

High tobacco consumption is causally associated with increased all-cause mortality in a general population sample of 55,568 individuals, but not with short telomeres: a Mendelian randomization study.

BACKGROUND: High cumulative tobacco consumption is associated with short telomeres and with increased all-cause mortality. We tested the hypothesis that high tobacco consumption is causally associated with short telomeres and with increased all-cause mortality. METHODS: We studied 55,568 individuals including 32,823 ever smokers from the Danish general population, of whom 3430 died during 10 years of follow-up. All had telomere length measured, detailed information on smoking history, and CHRNA3 rs1051730 genotype, which is associated with tobacco consumption, determined. In a Mendelian randomization study, we conducted observational, genetic, and mediation analyses. RESULTS: First, tobacco consumption was 21.1 pack-years in non-carriers, 22.8 in heterozygotes and 24.8 in homozygotes (P-trend<0.001). Second, the observational multivariable adjusted hazard ratio for all-cause mortality was 1.12 [95% confidence interval (CI): 1.09, 1.15] per doubling in tobacco consumption. In Mendelian randomization analysis, the hazard ratio was 1.08 (1.02, 1.14) per minor CHRNA3 allele in ever smokers. Third, in observational analysis telomeres shortened with -13 base pairs (-18, -8) per doubling in tobacco consumption. In Mendelian randomization analysis, the estimate was +3 base pairs (-10, +15) per minor CHRNA3 allele. Finally, individuals with the shortest vs longest telomeres had a multivariable adjusted hazard ratio of 1.30 (1.13, 1.50) for all-cause mortality; however, in mediation analysis short telomeres explained only +0.4% (-3.5%, +4.3%) of the association between high tobacco consumption and increased all-cause mortality. CONCLUSIONS: High tobacco consumption is causally associated with increased all-cause mortality. High cumulative tobacco consumption is associated with short telomeres observationally, but there is no clear genetic association.

Increased body mass index, elevated C-reactive protein, and short telomere length.

CONTEXT: Obesity is associated with short telomere length. The cause of this association is unknown. OBJECTIVE: We hypothesized that genetically increased body mass index (BMI) is associated with telomere length shortening and that low-grade inflammation might contribute through elevated C-reactive protein. SETTING AND DESIGN: We studied 45,069 individuals from the Copenhagen General Population Study with measurements of leukocyte telomere length, BMI, and C-reactive protein in a Mendelian randomization study. Using the three obesity-associated polymorphisms FTO rs9939609, MC4R rs17782313, and TMEM18 rs6548238, and the CRP promoter polymorphism rs3091244 in instrumental variable analyses, we estimated the associations between genetically increased BMI and telomere length and between genetically increased C-reactive protein and telomere length. RESULTS: In multivariable-adjusted observational analyses, telomere length decreased with seven base pairs (95% confidence interval, -9--5) per unit increase in BMI, and further adjustment for C-reactive protein attenuated this association to -5 base pairs (-8--3). In accordance, instrumental variable analysis showed a non-significant telomere length shortening of six base pairs (-37-25) per unit increase in genetically determined BMI. Furthermore, in observational analyses, telomere length decreased with nine base pairs (-16--2) for a doubling in C-reactive protein, supported by the instrumental variable analyses showing a corresponding genetically determined decrease of 66 base pairs (-124--7). CONCLUSIONS: High BMI is associated with short telomere length observationally. This might possibly be mediated through elevated C-reactive protein, given that genetically elevated C-reactive protein levels are associated with short telomere length.

Telomere shortening unrelated to smoking, body weight, physical activity, and alcohol intake: 4,576 general population individuals with repeat measurements 10 years apart.

Cross-sectional studies have associated short telomere length with smoking, body weight, physical activity, and possibly alcohol intake; however, whether these associations are due to confounding is unknown. We tested these hypotheses in 4,576 individuals from the general population cross-sectionally, and with repeat measurement of relative telomere length 10 years apart. We also tested whether change in telomere length is associated with mortality and morbidity in the general population. Relative telomere length was measured with quantitative polymerase chain reaction. Cross-sectionally at the first examination, short telomere length was associated with increased age (P for trend across quartiles = 3 × 10(-77)), current smoking (P = 8 × 10(-3)), increased body mass index (P = 7 × 10(-14)), physical inactivity (P = 4 × 10(-17)), but not with increased alcohol intake (P = 0.10). At the second examination 10 years later, 56% of participants had lost and 44% gained telomere length with a mean loss of 193 basepairs. Change in leukocyte telomere length during 10 years was associated inversely with baseline telomere length (P<1 × 10(-300)) and age at baseline (P = 1 × 10(-27)), but not with baseline or 10-year inter-observational tobacco consumption, body weight, physical activity, or alcohol intake. Prospectively during a further 10 years follow-up after the second examination, quartiles of telomere length change did not associate with risk of all-cause mortality, cancer, chronic obstructive pulmonary disease, diabetes mellitus, ischemic cerebrovascular disease, or ischemic heart disease. In conclusion, smoking, increased body weight, and physical inactivity were associated with short telomere length cross-sectionally, but not with telomere length change during 10 years observation, and alcohol intake was associated with neither. Also, change in telomere length did not associate prospectively with mortality or morbidity in the general population.

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.

A genome-wide association scan (GWAS) for mean telomere length within the COGS project: identified loci show little association with hormone-related cancer risk.

Mean telomere length (TL) in blood cells is heritable and has been reported to be associated with risks of several diseases, including cancer. We conducted a meta-analysis of three GWAS for TL (total n=2240) and selected 1629 variants for replication via the "iCOGS" custom genotyping array. All ∼200 000 iCOGS variants were analysed with TL, and those displaying associations in healthy controls (n = 15 065) were further tested in breast cancer cases (n = 11 024). We found a novel TL association (Ptrend < 4 × 10(-10)) at 3p14.4 close to PXK and evidence (Ptrend < 7 × 10(-7)) for TL loci at 6p22.1 (ZNF311) and 20q11.2 (BCL2L1). We additionally confirmed (Ptrend < 5 × 10(-14)) the previously reported loci at 3q26.2 (TERC), 5p15.3 (TERT) and 10q24.3 (OBFC1) and found supportive evidence (Ptrend < 5 × 10(-4)) for the published loci at 2p16.2 (ACYP2), 4q32.2 (NAF1) and 20q13.3 (RTEL1). SNPs tagging these loci explain TL differences of up to 731 bp (corresponding to 18% of total TL in healthy individuals), however, they display little direct evidence for association with breast, ovarian or prostate cancer risks.

Short telomere length, cancer survival, and cancer risk in 47102 individuals.

BACKGROUND: Recent meta-analyses have suggested that short telomere length was associated with increased risk of cancer. We therefore tested the hypotheses that short telomere length was associated with increased risk of cancer and with increased risk of early death after cancer. METHODS: We measured leukocyte telomere length in a prospective study of 47 102 Danish general population participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. Participants were followed for up to 20 years for cancer diagnosis and death. Follow-up was 100% complete. All statistical tests were two-sided. RESULTS: Telomere length decreased linearly with increasing age (P <.001). During follow-up, we observed 3142 first cancers and, among these individuals, 1730 deaths. Decreasing quartiles of telomere length were associated with decreasing survival after cancer (log-rank P <.001). Multivariable-adjusted hazard ratios of early death were 1.31 (95% confidence interval [CI] = 1.14 to 1.52) in individuals in the quartile and 1.43 (95% CI = 1.13 to 1.80) in individuals in the decile with the shortest telomeres vs the longest. Unadjusted hazard ratios of cancer risk were 1.74 (95% CI = 1.58 to 1.93) and 2.00 (95% CI = 1.70 to 2.35) in individuals in the quartile and decile with the shortest vs longest telomeres; however, multivariable adjustment changed these hazard ratios to 0.98 (95% CI = 0.88 to 1.08) and 0.95 (95% CI = 0.80 to 1.11), mainly because of age adjustment. CONCLUSIONS: Short telomere length is associated with reduced survival after cancer but not with cancer risk. The latter contrasts with findings from recent meta-analyses.

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.

Identification of 23 new prostate cancer susceptibility loci using the iCOGS custom genotyping array.

Prostate cancer is the most frequently diagnosed cancer in males in developed countries. To identify common prostate cancer susceptibility alleles, we genotyped 211,155 SNPs on a custom Illumina array (iCOGS) in blood DNA from 25,074 prostate cancer cases and 24,272 controls from the international PRACTICAL Consortium. Twenty-three new prostate cancer susceptibility loci were identified at genome-wide significance (P < 5 × 10(-8)). More than 70 prostate cancer susceptibility loci, explaining ∼30% of the familial risk for this disease, have now been identified. On the basis of combined risks conferred by the new and previously known risk loci, the top 1% of the risk distribution has a 4.7-fold higher risk than the average of the population being profiled. These results will facilitate population risk stratification for clinical studies.

Multiple independent variants at the TERT locus are associated with telomere length and risks of breast and ovarian cancer.

TERT-locus SNPs and leukocyte telomere measures are reportedly associated with risks of multiple cancers. Using the Illumina custom genotyping array iCOGs, we analyzed ∼480 SNPs at the TERT locus in breast (n = 103,991), ovarian (n = 39,774) and BRCA1 mutation carrier (n = 11,705) cancer cases and controls. Leukocyte telomere measurements were also available for 53,724 participants. Most associations cluster into three independent peaks. The minor allele at the peak 1 SNP rs2736108 associates with longer telomeres (P = 5.8 × 10(-7)), lower risks for estrogen receptor (ER)-negative (P = 1.0 × 10(-8)) and BRCA1 mutation carrier (P = 1.1 × 10(-5)) breast cancers and altered promoter assay signal. The minor allele at the peak 2 SNP rs7705526 associates with longer telomeres (P = 2.3 × 10(-14)), higher risk of low-malignant-potential ovarian cancer (P = 1.3 × 10(-15)) and greater promoter activity. The minor alleles at the peak 3 SNPs rs10069690 and rs2242652 increase ER-negative (P = 1.2 × 10(-12)) and BRCA1 mutation carrier (P = 1.6 × 10(-14)) breast and invasive ovarian (P = 1.3 × 10(-11)) cancer risks but not via altered telomere length. The cancer risk alleles of rs2242652 and rs10069690, respectively, increase silencing and generate a truncated TERT splice variant.

Short telomere length, lung function and chronic obstructive pulmonary disease in 46,396 individuals.

BACKGROUND: A previous case-control study of 100 individuals found that short telomere length was associated with a 28-fold increased risk of chronic obstructive pulmonary disease (COPD). OBJECTIVES: To test the hypothesis that short telomere length is associated with reduced lung function and an increased risk of COPD. METHODS: Observational study of 46 396 individuals from the Danish general population. MEASUREMENTS: Leucocyte telomere length and spirometry were measured. COPD was defined using either fixed forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <0.70 as suggested by the Global initiative for chronic Obstructive Lung Disease (GOLD) or FEV1/FVC below the lower limit of normal (LLN). RESULTS: Telomere length decreased significantly with increasing age (p<10(-300)). FEV1, FVC and FEV1/FVC decreased with decreasing telomere length quartiles (p trend: 5 × 10(-51), 5 × 10(-35) and 6 × 10(-137), respectively), but the associations attenuated after age and multivariable adjustment. The risk of COPD increased with decreasing telomere length quartile (p trend: p=7 × 10(-92) for GOLD; p=8 × 10(-44) for FEV1/FVC below LLN), but associations also attenuated after adjustment. Unadjusted and multivariable adjusted OR for shortest versus longest telomere length quartiles were 2.06 (95% CI 1.91 to 2.22) and 1.15 (95% CI 1.06 to 1.25) for GOLD and 1.73 (95% CI 1.60 to 1.88) and 1.19 (95% CI 1.09 to 1.30) for FEV1/FVC below LLN, respectively. Per 1000 base pairs decrease in telomere length, the multivariable adjusted OR was 1.07 (95% CI 1.03 to 1.10) for GOLD and 1.07 (95% CI 1.03 to 1.11) for FEV1/FVC below LLN. CONCLUSIONS: Short telomere length is associated with decreased lung function and with increased risk of COPD, but the associations are markedly attenuated after adjustment. Our data support a modest correlation between telomere length and the lung function indices examined.

A meta-analysis of genome-wide association studies to identify prostate cancer susceptibility loci associated with aggressive and non-aggressive disease.

Genome-wide association studies (GWAS) have identified multiple common genetic variants associated with an increased risk of prostate cancer (PrCa), but these explain less than one-third of the heritability. To identify further susceptibility alleles, we conducted a meta-analysis of four GWAS including 5953 cases of aggressive PrCa and 11 463 controls (men without PrCa). We computed association tests for approximately 2.6 million SNPs and followed up the most significant SNPs by genotyping 49 121 samples in 29 studies through the international PRACTICAL and BPC3 consortia. We not only confirmed the association of a PrCa susceptibility locus, rs11672691 on chromosome 19, but also showed an association with aggressive PrCa [odds ratio = 1.12 (95% confidence interval 1.03-1.21), P = 1.4 × 10(-8)]. This report describes a genetic variant which is associated with aggressive PrCa, which is a type of PrCa associated with a poorer prognosis.

CHEK2*1100delC heterozygosity in women with breast cancer associated with early death, breast cancer-specific death, and increased risk of a second breast cancer.

PURPOSE: We tested the hypotheses that CHEK2*1100delC heterozygosity is associated with increased risk of early death, breast cancer-specific death, and risk of a second breast cancer in women with a first breast cancer. PATIENTS AND METHODS: From 22 studies participating in the Breast Cancer Association Consortium, 25,571 white women with invasive breast cancer were genotyped for CHEK2*1100delC and observed for up to 20 years (median, 6.6 years). We examined risk of early death and breast cancer-specific death by estrogen receptor status and risk of a second breast cancer after a first breast cancer in prospective studies. RESULTS: CHEK2*1100delC heterozygosity was found in 459 patients (1.8%). In women with estrogen receptor-positive breast cancer, multifactorially adjusted hazard ratios for heterozygotes versus noncarriers were 1.43 (95% CI, 1.12 to 1.82; log-rank P = .004) for early death and 1.63 (95% CI, 1.24 to 2.15; log-rank P < .001) for breast cancer-specific death. In all women, hazard ratio for a second breast cancer was 2.77 (95% CI, 2.00 to 3.83; log-rank P < .001) increasing to 3.52 (95% CI, 2.35 to 5.27; log-rank P < .001) in women with estrogen receptor-positive first breast cancer only. CONCLUSION: Among women with estrogen receptor-positive breast cancer, CHEK2*1100delC heterozygosity was associated with a 1.4-fold risk of early death, a 1.6-fold risk of breast cancer-specific death, and a 3.5-fold risk of a second breast cancer. This is one of the few examples of a genetic factor that influences long-term prognosis being documented in an extensive series of women with breast cancer.

Short telomere length, myocardial infarction, ischemic heart disease, and early death.

OBJECTIVE: We tested the hypothesis that short telomere length is associated with increased risk of myocardial infarction, ischemic heart disease, and early death. METHODS AND RESULTS: We measured leukocyte telomere length in 2 prospective studies of 19 838 Danish general population participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. Participants were followed for up to 19 years for incident myocardial infarction (n=929), ischemic heart disease (n=2038), and death (n=4342). Follow-up was 100% complete. Telomere length decreased linearly with increasing age in women and men in both studies (P=7×10(-74) to P=3×10(-125)). Multifactorially adjusted hazard ratios were 1.10 (95% CI 1.01-1.19) for myocardial infarction, 1.06 (1.00-1.11) for ischemic heart disease, and 1.09 (1.05-1.13) for early death per 1000-base pair decrease in telomere length. The multifactorially adjusted hazard ratios for the shortest versus the longest decile of telomere length were 1.49 (1.07-2.07) for myocardial infarction, 1.24 (1.01-1.53) for ischemic heart disease, and 1.25 (1.07-1.46) for early death. CONCLUSION: Short telomere length is associated with only modestly increased risk of myocardial infarction, ischemic heart disease, and early death.

CHEK2*1100delC and risk of malignant melanoma: Danish and German studies and meta-analysis.

It is possible that reduced function of DNA repair and cell-cycle control genes increases the individual susceptibility to malignant melanoma. As CHEK2 is a cell-cycle master controller, we tested the hypothesis that heterozygosity for the frameshift alteration CHEK2*1100delC is associated with increased risk of malignant melanoma. First, we performed case-control studies of 1,152 Danish and 752 German individuals with malignant melanoma compared with 9,142 Danish and 3,718 German controls. Second, we performed a meta-analysis of CHEK2*1100delC and malignant melanoma, involving 2,619 cases and 17,481 controls. Third, we examined the risk of malignant melanoma associated with CHEK2*1100delC heterozygosity in an analysis stratified for sun exposure, as well as for subtype and location on the body. The odds ratios for malignant melanoma for CHEK2(*)1100del heterozygotes compared with those for noncarriers were 2.01 (95% confidence interval (CI), 1.03-3.91) in Danes, 1.42 (95% CI, 0.46-4.31) in Germans, and 1.79 (95% CI, 1.02-3.17) in Danes and Germans combined. In a meta-analysis, the odds ratio of malignant melanoma for CHEK2*1100delC heterozygotes compared with that for noncarriers was 1.81 (95% CI, 1.07-3.05). Stratifications did not alter these results. CHEK2*1100delC heterozygotes have a twofold risk of malignant melanoma compared with noncarriers.