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Open Access Case report

MC1R variants predisposing to concomitant primary cutaneous melanoma in a monozygotic twin pair

Cristina Pellegrini1, Maria Concetta Fargnoli1, Mariano Suppa1 and Ketty Peris12*

Author Affiliations

1 Department of Dermatology, University of L’Aquila, L’Aquila, Italy

2 Department of Dermatology, University of L’Aquila, via Vetoio - Coppito 2, 67100, L’Aquila, Italy

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BMC Medical Genetics 2012, 13:81  doi:10.1186/1471-2350-13-81

The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2350/13/81


Received:11 June 2012
Accepted:3 September 2012
Published:14 September 2012

© 2012 Pellegrini et al.; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Concomitant primary cutaneous melanoma in monozygotic twins has been reported in only two pairs but in neither of them genetic analysis was performed. Two high-penetrance susceptibility genes, CDKN2A and CDK4 and one low-penetrance gene, MC1R, are well-defined genetic risk factors for melanoma. MITF has been recently identified as a novel intermediate risk melanoma-predisposing gene.

Case presentation

We describe the extraordinary occurrence of a primary cutaneous invasive melanoma in two 44-year-old identical, female twins, on the same body site within 30 days of each other and report for the first time the genetic analysis of melanoma susceptibility genes in both twins. Data on characteristics of the twins were collected through a standardized questionnaire and skin examination. Exons 1α, 1β, 2 and 3 of CDKN2A, exon 2 of CDK4, the entire open reading frame of MC1R and the recently described MITF c.952 G > A (p.Glu318Lys) variant were investigated by direct sequencing. Sequencing analysis of the high-penetrance susceptibility genes showed no changes in CDKN2A and in exon 2 of the CDK4 gene. Both patients were heterozygous for the same CDKN2A UTR c.*29C > G variant. Interestingly, the same two heterozygous variants of the MC1R were identified in both twins: the c.451C > T (p.Arg151Cys) and the c.456C > A (p.Tyr152*) variants. Neither patient showed the c.952 G > A (p.Glu318Lys) substitution in the MITF gene.

Conclusions

Identification of two high-risk MC1R variants in our identical twins in the absence of CDKN2A and CDK4 mutations highlights the contribution of low penetrance genes, such as MC1R, in melanoma susceptibility.

Keywords:
Melanoma; Monozygotic twins; CDKN2A; CDK4; MC1R; MITF; Genetic susceptibility

Background

Genetic, phenotypic and environmental factors are known to affect melanoma risk. Two high-penetrance susceptibility genes, CDKN2A (cyclin-dependent kinase inhibitor 2A, MIM 600160) and CDK4 (cyclin-dependent kinase 4, MIM 123829) and one low-penetrance gene, MC1R (melanocortin-1 receptor, MIM 155555), have been identified so far as genetic risk factors for melanoma [1-3]. CDKN2A is the major melanoma susceptibility gene, mutated in approximately 40 % of melanoma-prone families with at least three affected members. Predisposing mutations in CDK4 have been identified in a limited number of melanoma families worldwide. Allelic variants in the MC1R gene, important in the pigmentation process, have been associated with increased melanoma risk, with the strongest effect observed for red hair color (RHC) variants (p.ArgR151Cys, p.Arg160Trp, p.Asp294His). Recently, whole genome sequencing lead to the identification of MITF (microphtalmia-associated transcription factor, MIM 156845) as a novel melanoma-predisposing gene with the p.Glu318Lys variant defined as an intermediate risk variant [4].

We describe the extraordinary occurrence of a primary cutaneous invasive melanoma in two 44-year-old female, identical twins, on the same body site within 30 days of each other and report for the first time genetic analysis of melanoma susceptibility genes in both twins.

Case presentation

A pair of female monozygotic twins who were included in a surveillance program at our Pigmented Lesion Clinic for the presence of multiple atypical nevi and at risk phenotype (Figure 1A) had been lost of follow-up over the last two years due to the 2009 earthquake in L’Aquila. Twin-1 presented with a one-year history of an irregularly-shaped, pink, light to dark brown, slowly growing plaque with irregular borders located on the right anterior upper trunk (Figure 1B). Thirty days later, twin-2 was examined for an asymmetrical, pink to light brown melanocytic lesion which had developed approximately 4 months earlier on the right anterior lower trunk (Figure 1C). Both patients referred a pre- existing pigmented lesion which changed in color and size. Dermatoscopic analysis showed irregular dots/globules, irregular streaks and a polymorphic vascular pattern in both cases. Histopathological examination showed a superficial spreading melanoma (SSM), 0.65 mm in Breslow thickness in twin-1 and a 0.33 mm thick SSM in twin-2. Both patients were skin type 1 (red hair, green eyes, fair-skinned, many ephelides) and were affected by the atypical mole syndrome with a total of 508 melanocytic nevi in twin-1 and of 375 nevi in twin-2. They reported numerous episodes of sunburns during childhood/adolescence, but different acute sun exposure habits in the adult life with longer recreational sun exposure (6 hours/day/4 weeks/year) for twin-1 than twin-2 (2 hours/day/2 weeks/year). They had neither personal nor family history of melanoma and twin-1 had three basal cell carcinomas excised.

thumbnailFigure 1. Phenotypic appearance of the twins and of their melanomas and identified germline MC1R variants. (A) Phenotypic features of twin-1 (left) and twin-2 (right); (B) Clinical image of twin-1’s melanoma located on the right anterior upper trunk; (C) Clinical image of twin-2’s melanoma excised from the right anterior lower trunk; (D) Heterozygous substitutions at codons 151 and 152 of the MC1R gene (NCBI accession NM_002386.3) identified in both twins.

Genetic analysis

Genomic DNA was isolated from whole blood of both patients using QIAamp® DNA Blood kit (Qiagen, Hilden, Germany). Exons 1α, 1β, 2 and 3, including the exon-intron boundaries of CDKN2A (NCBI accession NM_000077.3), exon 2 of CDK4 (NCBI accession NM_000075.3) and the entire open reading frame of MC1R (NCBI accession NM_002386.3) were amplified using PCR and directly sequenced on ABI Prism® 310 Genetic Analyzer (Applied Biosystems, Foster City, CA) as described previously [5,6]. The recently described MITF c.952 G > A (p.Glu318Lys) variant (NCBI accession NM_000248.3) was screened by direct sequencing of a PCR-amplified 589 amplicon using the following primers: forward, 5'-TACATTCCCTCTGGTATTGT-3'; reverse, 5'-AGCAGTTTGTGCGAATGCA-3'. Primers for PCR amplification were designed from the MITF genomic nucleotide sequence (NCBI accession NG_011631.1) and were the followings: forward, 5'-TACATTCCCTCTGGTATTGT-3'; reverse 5'-AGCAGTTTGTGCGAATGCA-3'. An amplicon of 589 bp was obtained by standard PCR using 1.25 U of AmpliTaq Gold® 360 (Applied Biosystems) in a 50-μl volume, containing the 1X reaction buffer provided by the manufacturer, 1.6 mM of MgCl2, 200 μM of each deoxynucleoside triphosphate, 0.2 μM of each primer and 100 ng genomic DNA template. Five per cent dimethyl sulfoxide was added to the reaction solution. PCR amplification conditions were as follows: 95°C for 7 min, 35 cycles of 94°C for 1 min, 52.2°C for 1 min, and 72°C for 1 min, followed by a final extension step at 72°C for 7 min. Written informed consent was obtained from our patients under an Institutional Review Board-approved protocol.

Sequencing analysis showed no changes in the coding region and in the 5’UTR region of CDKN2A, although both patients were heterozygous for the same UTR c.*29C > G variant. No mutations were detected in exon 2 of the CDK4 gene. Interestingly, sequencing of the MC1R identified the same two heterozygous variants in both twins: the c.451C > T (p.Arg151Cys) and the c.456C > A (p.Tyr152*) variants (Figure 1D). Neither patient showed the c.1075 G > A (p.Glu318Lys) substitution in the MITF gene.

Conclusions

The occurrence of melanoma concordant for site and age of onset in monozygotic twins has been reported in only two pairs but in neither of them genetic analysis was performed. St-Arneault et al. [7] described two identical male twins (from a set of triplets) who developed melanoma at age 53, at the same site and within a time frame of 2 months, while the fraternal triplet showed no evidence of tumour. More recently, Rao et al.[8] reported two 71-year-old, identical female twins, diagnosed with melanoma at the same time (within 10 days of each other) and location (right calf). Our patients were skin type 1 as the latter pair but they were younger than both pairs.

Studies in twin pairs are of great interest to estimate the relative effect of genetic and environmental influences on melanoma development. In a recent large population-based study of Australian twins, genetic influences were shown to be a significant source of variation in liability to melanoma with identical twins being more than four times more likely to be affected with melanoma if they had an affected co-twin than non-identical twins [9].

MC1R variants have been associated with a 1.2 to 2.4-fold increased risk of melanoma with an additive effect for multiple variants [10-12]. A double variation in the MC1R gene, the c.451C > T (p.Arg151Cys) and the c.456C > A (p.Tyr152*), was detected in our twins. The p.Arg151Cys has been shown to confer the highest melanoma risk with summary estimates ranging from 1.78 (95%CI 1.45–2.20) to 1.93 (95%CI 1.54–2.41) in two recent meta-analyses [10,11]. We previously reported a significant association of the p.Arg151Cys allele with melanoma risk in a population from central Italy, with an OR of 2.94 (95%CI, 1.04–8.31) [6]. In functional studies, the p.Arg151Cys mutant receptor showed a reduced cell surface expression with intracellular retention and a corresponding impairment in cAMP coupling [13]. The nonsense p.Tyr152* is a rare RHC variant associated with a severe functional impairment of the MC1R due to the lack of the last four transmembrane fragments [14,15]. Interestingly, MC1R-associated melanoma risk has been shown to increase with the number of variants in the genotype supporting the MC1R-associated susceptibility in our patients carrying two nonfunctional MC1R variants. Finally, carriers of MC1R RHC variants have been recently suggested to develop melanomas lacking significant pigmentation [16,17] as also observed in the hypomelanotic melanomas of our twins.

In addition to the well-defined association of MC1R with melanoma, other low-penetrance melanoma risk alleles have been described in genes related to pigmentation, nevus count, immune responses, DNA repair, metabolism and the vitamin D receptor [12]. In this regard, we cannot rule out the possible involvement of other low-penetrance melanoma susceptibility alleles in our twins since they were not genotyped in our patients.

The concordance for cutaneous melanoma as well as the congruence for its location and identity of the age of onset in monozygotic twins support the role of genetic rather than environmental factors in the development of melanoma. Detection of two high-risk MC1R variants in our identical twins in the absence of CDKN2A and CDK4 mutations highlights the contribution of low penetrance genes, such as MC1R, in melanoma susceptibility, although additional known or as yet unknown genetic risk factors might be involved.

Consent

Written informed consent was obtained from both patients for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Abbreviations

CDKN2A: Cyclin-dependent kinase inhibitor 2A; CDK4: Cyclin-dependent kinase 4; MC1R: Melanocortin-1 receptor; MITF: Microphtalmia-associated transcription factor; RHC: Red hair color; SSM: Superficial spreading melanoma.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

All authors have read and approved the final manuscript. CP carried out the molecular genetic studies, participated in the analysis and interpretation of data and drafted the manuscript; MCF was involved in conception and design of the study, supervised the genetic analysis and participated in the interpretation of data and drafting the manuscript; MS collected the clinical data and participated in drafting the manuscript; KP diagnosed the patients, was involved in conception and design of the study and revised the manuscript critically.

References

  1. Fargnoli MC, Argenziano G, Zalaudek I, Peris K: High- and low-penetrance cutaneous melanoma susceptibility genes.

    Expert Rev Anticancer Ther 2006, 6:657-670. PubMed Abstract | Publisher Full Text OpenURL

  2. Goldstein AM, Chan M, Harland M, Gillanders EM, Hayward NK, Avril MF, Azizi E, Bianchi-Scarra G, Bishop DT, Bressac-de Paillerets B, Bruno W, Calista D, Cannon Albright LA, Demenais F, Elder DE, Ghiorzo P, Gruis NA, Hansson J, Hogg D, Holland EA, Kanetsky PA, Kefford RF, Landi MT, Lang J, Leachman SA, Mackie RM, Magnusson V, Mann GJ, Niendorf K, Newton Bishop J, Palmer JM, Puig S, Puig-Butille JA, de Snoo FA, Stark M, Tsao H, Tucker MA, Whitaker L, Yakobson E, Melanoma Genetics Consortium (GenoMEL): High-risk melanoma susceptibility genes and pancreatic cancer, neural system tumors, and uveal melanoma across GenoMEL.

    Cancer Res 2006, 66:9818-9828. PubMed Abstract | Publisher Full Text OpenURL

  3. Meyle KD, Guldberg P: Genetic risk factors for melanoma.

    Hum Genet 2009, 126:499-510. PubMed Abstract | Publisher Full Text OpenURL

  4. Yokoyama S, Woods SL, Boyle GM, Aoude LG, MacGregor S, Zismann V, Gartside M, Cust AE, Haq R, Harland M, Taylor JC, Duffy DL, Holohan K, Dutton-Regester K, Palmer JM, Bonazzi V, Stark MS, Symmons J, Law MH, Schmidt C, Lanagan C, O'Connor L, Holland EA, Schmid H, Maskiell JA, Jetann J, Ferguson M, Jenkins MA, Kefford RF, Giles GG, Armstrong BK, Aitken JF, Hopper JL, Whiteman DC, Pharoah PD, Easton DF, Dunning AM, Newton-Bishop JA, Montgomery GW, Martin NG, Mann GJ, Bishop DT, Tsao H, Trent JM, Fisher DE, Hayward NK, Brown KM: A novel recurrent mutation in MITF predisposes to familial and sporadic melanoma.

    Nature 2011, 480:99-103. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  5. Peris K, Fargnoli MC, Pacifico A, Surrenti T, Stolz W, Wolf P, Soyer HP, Chimenti S: CDKN2A and MC1R mutations in patients with sporadic multiple primary melanoma.

    J Invest Dermatol 2004, 122:1327-1330. PubMed Abstract | Publisher Full Text OpenURL

  6. Fargnoli MC, Altobelli E, Keller G, Chimenti S, Höfler H, Peris K: Contribution of melanocortin-1 receptor gene variants to sporadic cutaneous melanoma risk in a population in central Italy: a case-control study.

    Melanoma Res 2006, 16:175-182. PubMed Abstract | Publisher Full Text OpenURL

  7. St-Arneault G, Nagel G, Kirkpatrick D, Kirkpatrick R, Holland JF: Melanoma in twins Cutaneous malignant melanoma in identical twins from a set of triplets.

    Cancer 1970, 25:672-677. PubMed Abstract | Publisher Full Text OpenURL

  8. Rao BK, Noor O, Thosani MK: Identical twins with primary cutaneous melanoma presenting at the same time and location.

    Am J Dermatopathol 2008, 30:182-184. PubMed Abstract | Publisher Full Text OpenURL

  9. Shekar SN, Duffy DL, Youl P, Baxter AJ, Kvaskoff M, Whiteman DC, Green AC, Hughes MC, Hayward NK, Coates M, Martin NG: A population-based study of Australian twins with melanoma suggests a strong genetic contribution to liability.

    J Invest Dermatol 2009, 129:2211-2219. PubMed Abstract | Publisher Full Text OpenURL

  10. Raimondi S, Sera F, Gandini S, Iodice S, Caini S, Maisonneuve P, Fargnoli MC: MC1R variants, melanoma and red hair color phenotype: a meta-analysis.

    Int J Cancer 2008, 122:2753-2760. PubMed Abstract | Publisher Full Text OpenURL

  11. Williams PF, Olsen CM, Hayward NK, Whiteman DC: Melanocortin 1 receptor and risk of cutaneous melanoma: a meta-analysis and estimates of population burden.

    Int J Cancer 2011, 129:1730-1740. PubMed Abstract | Publisher Full Text OpenURL

  12. Ward KA, Lazovich D, Hordinsky MK: Germline melanoma susceptibility and prognostic genes: A review of the literature.

    J Am Acad Dermatol 2012.

    [Epub ahead of print] PMID: 22583682

    OpenURL

  13. Beaumont KA, Shekar SN, Newton RA, James MR, Stow JL, Duffy DL, Sturm RA: Receptor function, dominant negative activity and phenotype correlations for MC1R variant alleles.

    Hum Mol Genet 2007, 16:2249-2260. PubMed Abstract | Publisher Full Text OpenURL

  14. García-Borrón JC, Sánchez-Laorden BL, Jiménez-Cervantes C: Melanocortin-1 receptor structure and functional regulation.

    Pigment Cell Res 2005, 18:393-410. PubMed Abstract | Publisher Full Text OpenURL

  15. Galore G, Azizi E, Scope A, Pavlotsky F, Yakobson E, Friedman E: The Y152X MC1R gene mutation: occurrence in ethnically diverse Jewish malignant melanoma patients.

    Melanoma Res 2007, 17:105-108. PubMed Abstract | Publisher Full Text OpenURL

  16. Cuéllar F, Puig S, Kolm I, Puig-Butille J, Zaballos P, Martí-Laborda R, Badenas C, Malvehy J: Dermoscopic features of melanomas associated with MC1R variants in Spanish CDKN2A mutation carriers.

    Br J Dermatol 2009, 160:48-53. PubMed Abstract | Publisher Full Text OpenURL

  17. Zalaudek I, Meiklejohn W, Argenziano G, Thurber AE, Sturm RA: "White" nevi and "red" melanomas: association with the RHC phenotype of the MC1R gene.

    J Invest Dermatol 2009, 129:1305-1307. PubMed Abstract | Publisher Full Text OpenURL

Pre-publication history

The pre-publication history for this paper can be accessed here:

http://www.biomedcentral.com/1471-2350/13/81/prepub