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The endothelin signaling pathway plays a crucial role in melanocyte differentiation and migration. In this study, we investigated whether germ-line mutations of endothelin receptor B (EDNRB), a gene involved in Hirsch-sprung disease (HSCR), could also predispose for malignant melanoma (MM). The coding region of EDNRB was sequenced in 137 MM patients and in 130 ethnically matched Caucasian control subjects. Six nonsynonymous EDNRB variants were found in 15 patients (11%), but only two were found in four control subjects (3%, odds ratio [OR] = 3.87, 95% confidence interval [CI] = 1.25 to 12; P = .012). Overall, 14 out of 15 MM patients carried EDNRB mutations reported in HSCR, some of which had previously been shown to lead to loss of function. In multivariable logistic regression analysis including skin type, eye and hair color, number of nevi, and dorsal lentigines (freckles), the association between EDNRB mutations and MM risk remained statistically significant (OR = 19.9, 95% CI = 1.34 to 296.2; P = .03). Our data strongly suggest that EDNRB is involved in predisposition for two different multigenic disorders, HSCR and melanoma. [ABSTRACT FROM AUTHOR]

As loss of KIT frequently occurs in melanoma progression, we hypothesized that KIT is implicated in predisposition to melanoma ( MM). Thus, we sequenced the KIT coding region in 112 familial MM cases and 143 matched controls and genotyped tag single-nucleotide polymorphisms ( SNPs) in two cohorts of melanoma patients and matched controls. Five rare KIT substitutions, all predicted possibly or probably deleterious, were identified in five patients, but none in controls [ RR = 2.26 (1.26-2.26)]. Expressed in melanocyte lines, three substitutions inhibited KIT signaling. Comparison with exomes database (7020 alleles) confirmed a significant excess of rare deleterious KIT substitutions in patients. Additionally, a common SNP, rs2237028, was associated with MM risk, and 6 KIT variants were associated with nevus count. Our data strongly suggest that rare KIT substitutions predispose to melanoma and that common variants at KIT locus may also impact nevus count and melanoma risk. [ABSTRACT FROM AUTHOR]

Abstract: Background and methods: Seven genetic biomarkers previously associated with melanoma were analysed in a meta-analysis conducted in three South European populations: five red hair colour (RHC) MC1R alleles, one SLC45A2 variant (p.Phe374Leu) and one thermosensitive TYR variant (p.Arg402Gln). The study included 1639 melanoma patients and 1342 control subjects. Results: The estimated odds ratio (OR) associated with carrying at least one MC1R RHC variant was 2.18 (95% confidence interval (CI): 1.86–2.55; p-value=1.02×10−21), with an additive effect for carrying two RHC variants (OR: 5.02, 95% CI: 2.88–8.94, p-value=3.91×10−8). The SLC45A2 variant, p.Phe374Leu, was significantly and strongly protective for melanoma in the three South European populations studied, with an overall OR value of 0.41 (95%CI: 0.33–0.50; p-value = 3.50×10−17). The association with melanoma of the TYR variant p.Arg402Gln was also statistically significant (OR: 1.50; 95%CI: 1.11–2.04; p-value=0.0089). Adjustment for all clinical potential confounders showed that melanoma risks attributable to MC1R and SLC45A2 variants strongly persisted (OR: 2.01 95%CI: 1.49–2.72 and OR: 0.50, 95%CI: 0.31–0.80, respectively), while the association of TYR p.Arg402Gln was no longer significant. In addition, stratification of clinical melanoma risk factors showed that the risk of melanoma was strong in those individuals who did not have clinical risk factors. Conclusion: In conclusion, our results show without ambiguity that in South European populations, MC1R RHC and SCL45A2 p.Phe374Leu variants are strong melanoma risk predictors, notably in those individuals who would not be identified as high risk based on their phenotypes or exposures alone. The use of these biomarkers in clinical practice could be promising and warrants further discussion. [Copyright &y& Elsevier]

Inherited MC1R variants modulate MITF transcription factor signaling, which in turn affects tumor cell proliferation, apoptosis, and DNA repair. The aim of this BioGenoMEL collaborative study in 10 melanoma cohorts was to test the hypothesis that inherited variants thereby moderate survival expectation. A survival analysis in the largest cohort (Leeds) was carried out adjusting for factors known to impact on survival. The results were then compared with data from nine smaller cohorts. The absence of any consensus MC1R alleles was associated with a significantly lower risk of death in the Leeds set (HR, 0.64; 95% CI, 0.46-0.89) and overall in the 10 data sets (HR, 0.78; 95% CI, 0.65-0.94) with some support from the nine smaller data sets considered together (HR, 0.83; 95% CI, 0.67-1.04). The data are suggestive of a survival benefit for inherited MC1R variants in melanoma patients. [ABSTRACT FROM AUTHOR]

Abstract: Background: Tyrosinase (TYR) is a key pigmentation gene that is highly polymorphic and responsible for the most common form of autosomal recessive albinism, OCA1. Objective: To assess the role of frequent and rare TYR variants in predisposition to skin cancer (SK) in the French population. Methods: We genotyped a frequent TYR variant (p.R402Q) in 1273 patients {1047 cutaneous melanoma (CM) and 226 basal cell carcinoma (BCC)} and 925 controls, and the full coding region of TYR was sequenced in 287 patients suspected of genetic predisposition to SK (familial and/or multiple SK and/or onset before 40 years) and 187 controls. Results: The homozygous p.R402Q variant was significantly associated with SK risk (P value=0.008; OR=1.57), and was mostly associated with multiple CM risk (P value=0.021; OR=2.50) and familial CM risk (P value=0.022; OR=2.16). In addition, 19 rare TYR variants, mainly albinism mutations, were identified in 15 patients and 8 controls. Among these, 3 clearly deleterious mutations (1 non-sense and 2 affecting mRNA splicing) were identified in 3 patients, one of which was homozygous. Conclusion: Our data confirmed the association of TYR p.R402Q with SK risk in the French population, and support that rare deleterious TYR variants may also play a role in multi-factorial genetic predisposition to SK. These results should be confirmed by replications studies. [Copyright &y& Elsevier]

Purpose: Xeroderma pigmentosum variant (XPV) is a rare recessive autosomal genodermatosis predisposing to multiple early onset skin cancers, including melanoma. XPV results from mutations of the POLH gene that encodes a DNA translesion polymerase. In this work, we tested the hypothesis that POLH variants could be associated with melanoma risk. Experimental design: A common non-synonymous POLH variant, c.1783A>G p.M595V, was genotyped in 1075 melanoma patients and in 1091 ethnic-matched controls from France. In addition, we searched for rare POLH variants by sequencing the entire coding sequence in 201 patients having a familial history of melanoma (n =123), sporadic multiple melanomas (n =65) and a melanoma associated with a skin carcinoma (n =13). Results: Overall, the c.1783G, p.595V allele was statistically associated with melanoma (respective allelic frequencies, 0.040 versus 0.022, P-value=1.17×10–3, odds ratio (OR)=1.86 [1.27–2.71]), which was further confirmed by a meta-analysis including 274 patients and 174 matched controls from Italy (P-value=7.7×10–4, OR=1.84 [1.29–2.63]). Interestingly, three non-synonymous POLH variants were identified in three patients (c.295G>A p.V99M, c.815T>C p.I272T and c.1745C>T p.S582L) which were absent in 352 chromosome controls from healthy subjects. Conclusions: Besides severe deficiencies in translesion synthesis which are major risks factors for skin carcinomas and melanomas, less deleterious POLH variants could act as low penetrance melanoma predisposing alleles. The ongoing identification of genetic markers implied in skin cancer predisposition could help to identify high-risk subjects as targets for clinical follow-up. Replication studies in other populations are awaited to assess these data. [Copyright &y& Elsevier]

A letter to the editor is presented about the genotyping of the allele A148T into two European populations from France and Italy to determine the contribution of the variant on melanoma risk.

The occuloalbinism 2 (OCA2) gene, localized at 15q11, encodes a melanosomal transmembrane protein that is involved in the most common form of human occulo-cutaneous albinism, a human genetic disorder characterized by fair pigmentation and susceptibility to skin cancer. We wondered whether allele variations at this locus could influence susceptibility to malignant melanoma (MM). In all, 10 intragenic single-nucleotide polymorphisms (SNPs) were genotyped in 113 patients with melanomas and in 105 Caucasian control subjects with no personal or family history of skin cancer. By comparing allelic distribution between cases and controls, we show that MM and OCA2 are associated (p value=0.030 after correction for multiple testing). Then, a recently developed strategy, the ‘combination test’ enabled us to show that a combination formed by two SNPs was most strongly associated to MM, suggesting a possible interaction between intragenic SNPs. In addition, the role of OCA2 on MM risk was also detected using a logistic model taking into account the presence of variants of the melanocortin 1 receptor gene (MC1R, a key pigmentation gene) and all pigmentation characteristics as melanoma risk factors. Our data demonstrate that a second pigmentation gene, in addition to MC1R, is involved in genetic susceptibility to melanoma.European Journal of Human Genetics (2005) 13, 913–920. doi:10.1038/sj.ejhg.5201415; published online 27 April 2005 [ABSTRACT FROM AUTHOR]