title: The melanocortin-1-receptor gene is the major freckle gene.
abstract: Ephelides and solar lentigines are different types of pigmented skin lesions. Ephelides appear early in childhood and are associated with fair skin type and red hair. Solar lentigines appear with increasing age and are a sign of photodamage. Both lesions are strong risk indicators for melanoma and non-melanoma skin cancer. Melanocortin-1-receptor (MC1R) gene variants are also associated with fair skin, red hair and melanoma and non-melanoma skin cancer. The purpose of this study was to investigate the relationship between MC1R gene variants, ephelides and solar lentigines. In a large case-control study, patients with melanoma and non-melanoma skin cancer and subjects without a history of skin cancer were studied. In all participants, the presence of ephelides in childhood and solar lentigines by physical examination was assessed according to strict definitions. The entire coding sequence of the MC1R gene was analyzed by single-strand conformation polymorphism analysis followed by sequence analyses. Carriers of one or two MC1R gene variants had a 3- and 11-fold increased risk of developing ephelides, respectively (both P < 0.0001), whereas the risk of developing severe solar lentigines was increased 1.5- and 2-fold (P = 0.035 and P < 0.0001), respectively. These associations were independent of skin type and hair color, and were comparable in patients with and without a history of skin cancer. The population attributable risk for ephelides to MC1R gene variants was 60%, i.e. 60% of the ephelides in the population was caused by MC1R gene variants. A dosage effect was found between the degree of ephelides and the number of MC1R gene variants. As nearly all individuals with ephelides were carriers of at least one MC1R gene variant, our data suggest that MC1R gene variants are necessary to develop ephelides. The results of the study also suggest that MC1R gene variants play a role, although less important, in the development of solar lentigines.
authors.affiliation: Department of Dermatology and Department of Clinical Epidemiology, Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Bastiaens
authors.forename: J
authors.initials: J
authors.lastname: ter Huurne
authors.forename: N
authors.initials: N
authors.lastname: Gruis
authors.forename: W
authors.initials: W
authors.lastname: Bergman
authors.forename: R
authors.initials: R
authors.lastname: Westendorp
authors.forename: B J
authors.initials: BJ
authors.lastname: Vermeer
authors.forename: J N
authors.initials: JN
authors.lastname: Bouwes Bavinck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D003627:Data Interpretation, Statistical; D005260:Female; D018628:Gene Dosage; D014644:Genetic Variation; D006200:Hair Color; D006801:Humans; D008297:Male; D008545:Melanoma / Q000209:etiology / Q000235:genetics*; D008548:Melanosis / Q000235:genetics*; D008875:Middle Aged; D018043:Receptors, Corticotropin / Q000235:genetics* / Q000502:physiology; D044101:Receptors, Melanocortin; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics*; D012879:Skin Physiological Phenomena; D013471:Sunburn / Q000150:complications; D013472:Sunlight
chemical_list: D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin