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MC1R genotypes and risk of melanoma before age 40 years: a population-based case-control-family study.

ABSTRACT: The contribution of melanocortin-1 receptor (MC1R) gene variants to the development of early-onset melanoma is unknown. Using an Australian population-based, case-control-family study, we sequenced MC1R for 565 cases with invasive cutaneous melanoma diagnosed between ages 18 and 39 years, 409 unrelated controls and 518 sibling controls. Variants were classified a priori into "R" variants (D84E, R142H, R151C, I155T, R160W, D294H) and "r" variants (all other nonsynonymous variants). We estimated odds ratios (OR) for melanoma using unconditional (unrelated controls) and conditional (sibling controls) logistic regression. The prevalence of having at least one R or r variant was 86% for cases, 73% for unrelated controls and 81% for sibling controls. R151C conferred the highest risk (per allele OR 2.57, 95% confidence interval 1.86-3.56 for the case-unrelated-control analysis and 1.70 (1.12-2.60) for the case-sibling-control analysis). When mutually adjusted, the ORs per R allele were 2.23 (1.77-2.80) and 2.06 (1.47-2.88), respectively, from the two types of analysis, and the ORs per r allele were 1.69 (1.33-2.13) and 1.25 (0.88-1.79), respectively. The associations were stronger for men and those with none or few nevi or with high childhood sun exposure. Adjustment for phenotype, nevi and sun exposure attenuated the overall log OR for R variants by approximately 18% but had lesser influence on r variant risk estimates. MC1R variants explained about 21% of the familial aggregation of melanoma. Some MC1R variants are important determinants of early-onset melanoma. The strength of association with melanoma differs according to the type and number of variants.

SUBMITTER: Cust AE

PROVIDER: S-EPMC4330189 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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MC1R genotypes and risk of melanoma before age 40 years: a population-based case-control-family study.

Cust Anne E AE Goumas Chris C Holland Elizabeth A EA Agha-Hamilton Chantelle C Aitken Joanne F JF Armstrong Bruce K BK Giles Graham G GG Kefford Richard F RF Schmid Helen H Hopper John L JL Mann Graham J GJ Jenkins Mark A MA

International journal of cancer 20120130 3

The contribution of melanocortin-1 receptor (MC1R) gene variants to the development of early-onset melanoma is unknown. Using an Australian population-based, case-control-family study, we sequenced MC1R for 565 cases with invasive cutaneous melanoma diagnosed between ages 18 and 39 years, 409 unrelated controls and 518 sibling controls. Variants were classified a priori into "R" variants (D84E, R142H, R151C, I155T, R160W, D294H) and "r" variants (all other nonsynonymous variants). We estimated o ...[more]

PMID: 22095472

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Project description:BackgroundMelanocortin-1 receptor (MC1R) gene variants are very common and are associated with melanoma risk, but their contribution to melanoma risk prediction compared with traditional risk factors is unknown. We aimed to 1) evaluate the separate and incremental contribution of MC1R genotype to prediction of early-onset melanoma, and compare this with the contributions of physician-measured and self-reported traditional risk factors, and 2) develop risk prediction models that include MC1R, and externally validate these models using an independent dataset from a genetically similar melanoma population.MethodsUsing data from an Australian population-based, case-control-family study, we included 413 case and 263 control participants with sequenced MC1R genotype, clinical skin examination and detailed questionnaire. We used unconditional logistic regression to estimate predicted probabilities of melanoma. Results were externally validated using data from a similar study in England.ResultsWhen added to a base multivariate model containing only demographic factors, MC1R genotype improved the area under the receiver operating characteristic curve (AUC) by 6% (from 0.67 to 0.73; P?<?0.001) and improved the quartile classification by a net 26% of participants. In a more extensive multivariate model, the factors that contributed significantly to the AUC were MC1R genotype, number of nevi and previous non-melanoma skin cancer; the AUC was 0.78 (95% CI 0.75-0.82) for the model with self-reported nevi and 0.83 (95% CI 0.80-0.86) for the model with physician-counted nevi. Factors that did not further contribute were sun and sunbed exposure and pigmentation characteristics. Adding MC1R to a model containing pigmentation characteristics and other self-reported risk factors increased the AUC by 2.1% (P?=?0.01) and improved the quartile classification by a net 10% (95% CI 1-18%, P = 0.03).ConclusionsAlthough MC1R genotype is strongly associated with skin and hair phenotype, it was a better predictor of early-onset melanoma than was pigmentation characteristics. Physician-measured nevi and previous non-melanoma skin cancer were also strong predictors. There might be modest benefit to measuring MC1R genotype for risk prediction even if information about traditional self-reported or clinically measured pigmentation characteristics and nevi is already available.

Project description:BACKGROUND: Cardiovascular diseases (CVD) are a major cause of death in people with AIDS. Factors contributing to atherosclerosis include traditional risk factors, antiretrovirals and inflammatory factors related to HIV infection. This study set out to compare risk factors associated with subclinical atherosclerosis in individuals under and over 40 years of age. METHODS: Case-control study with 697 HIV/AIDS individuals without HAART or who remain on their first antiretroviral regimen. Of the total, 351 individuals under 40 years and 346 over 40 years were analyzed separately. Subclinical atherosclerosis was assessed by carotid intima-media thickness, using B-mode ultrasound. Multivariate logistic regression was performed to find predictors of subclinical atherosclerosis in the entire group. Subsequent analysis excluded patients with major risk factors for CVD. Magnitudes of associations were expressed by odds ratio (OR) statistical significance, using a 95% confidence interval and p-value <0.05. RESULTS: In the <40 years group subclinical atherosclerosis was associated with male gender (OR: 2.77, 95% CI: 1.43-5.34), nonwhite race (OR: 3.01, 95% CI: 1.23-6.53), obesity (OR: 5.13, 95% CI: 1.79-14.7) and metabolic syndrome (OR: 3.30, 95% CI: 1.44-7.58). In the group ?40 years predictors of subclinical atherosclerosis were overweight and obesity (OR = 2.53, 95% CI, 0.85-7.54), current CD4 ?350 cells/mL (OR: 2.81, 95% CI: 1.22-6.47) and NNRTI use ? 5 years (OR: 2.65, 95% CI: 1.10-6.37) or PI use >5 years (OR: 1.81, 95% CI: 0.38-8.59). In the multivariate model excluding patients with major risk factors for CVD, age, male sex and nonwhite race were associated with subclinical atherosclerosis in the <40 y group, while in the ?40 y group, age, HIV viral load >10,000 copies and the use of NNRTI (OR: 7.60, 95% CI: 1.61-35.8) or PI ?5 years (OR: 3.62, 95% CI: 0.48-26.8) were associated with subclinical atherosclerosis. CONCLUSIONS: In young people the fight against obesity and metabolic syndrome is the main aim in the prevention of CVD. In individuals aged ?40 y, the prevention of obesity is also of great importance. Moreover, the effects of uncontrolled viremia and the prolonged use of HAART appear to be more harmful in the older group.

Dataset Information

MC1R genotypes and risk of melanoma before age 40 years: a population-based case-control-family study.

Publications

MC1R genotypes and risk of melanoma before age 40 years: a population-based case-control-family study.

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