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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To provide a state-of-the-art summary of currently available data about the genetics of cutaneous melanoma and nevi, we reviewed the pertinent literature and outlined the important findings on genetic analyses. Although the first English-language report of melanoma in 1820 contained a description of a melanoma-prone family, seminal studies by investigators at the National Cancer Institute and the University of Pennsylvania identified dysplastic nevi (DN) as an important melanoma precursor, suggested an autosomal dominant mode of inheritance for both melanoma and DN, and proposed that a melanoma-susceptibility gene (CMM1) was located on chromosome 1p36. This gene assignment has not yet been confirmed by independent investigators. A second melanoma gene, designated CMM2, has been mapped to chromosome 9p21. This gene assignment has been confirmed independently, and the cell cycle regulator p16INK4a has been proposed as a candidate gene; germline mutations in this gene have been identified in about half of melanoma-prone families. Germline mutations in the cyclin-dependent kinase gene CDK4 (chromosome 12q14) have recently been described in two melanoma kindreds; this finding likely represents a third melanoma gene. A heritable determinant for total nevus number has been suggested, as has the presence of a major gene responsible for total nevus density in melanoma-prone families. An autosomal dominant mode of inheritance for DN has been proposed, and evidence suggests that DN may be a pleiotropic manifestation of the 1p36 familial melanoma gene. Several studies have shown a surprisingly high prevalence of DN on the skin of family members of probands with DN. In light of the extensive evidence documenting that persons with DN (both sporadic and familial) have an increased prospective risk for melanoma, these family studies suggest that relatives of persons with DN should be examined for DN and for melanoma. Overall, genetic determinants have a major role in the pathogenesis of normal nevi, DN, and melanoma. Elucidating the molecular basis of these genetic events promises to enhance melanoma risk reduction strategies and thereby reduce melanoma-associated mortality.
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PMID:Genetics of cutaneous melanoma and nevi. 914 91

The CDKN2A gene encodes p16 (CDKN2A), a cell-cycle inhibitor protein which prevents inappropriate cell cycling and, hence, proliferation. Germ-line mutations in CDKN2A predispose to the familial atypical multiple-mole melanoma (FAMMM) syndrome but also have been seen in rare families in which only 1 or 2 individuals are affected by cutaneous malignant melanoma (CMM). We therefore sequenced exons 1alpha and 2 of CDKN2A using lymphocyte DNA isolated from index cases from 67 families with cancers at multiple sites, where the patterns of cancer did not resemble those attributable to known genes such as hMLH1, hMLH2, BRCA1, BRCA2, TP53 or other cancer susceptibility genes. We found one mutation, a mis-sense mutation resulting in a methionine to isoleucine change at codon 53 (M531) of exon 2. The individual tested had developed 2 CMMs but had no dysplastic nevi and lacked a family history of dysplastic nevi or CMM. Other family members had been diagnosed with oral cancer (2 persons), bladder cancer (1 person) and possibly gall-bladder cancer. While this mutation has been reported in Australian and North American melanoma kindreds, we did not observe it in 618 chromosomes from Scottish and Canadian controls. Functional studies revealed that the CDKN2A variant carrying the M531 change was unable to bind effectively to CDK4, showing that this mutation is of pathological significance. Our results have confirmed that CDKN2A mutations are not limited to FAMMM kindreds but also demonstrate that multi-site cancer families without melanoma are very unlikely to contain CDKN2A mutations.
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PMID:CDKN2A mutation in a non-FAMMM kindred with cancers at multiple sites results in a functionally abnormal protein. 938 68

Although the first English-language report of melanoma in 1820 contained a description of a melanoma-prone family, it was 1983 before formal genetic analysis suggested an autosomal dominant mode of inheritance for both melanoma and the then newly described melanoma precursor, dysplastic nevi (DN). Subsequent genetic studies have assumed this model to be correct, although when viewed in aggregate, the data are inconsistent. The first proposed melanoma gene (CMM1) was mapped to chromosome 1p36. This gene assignment has not been confirmed. A second melanoma gene, designated CMM2, has been mapped to chromosome 9p21. This gene assignment has been confirmed, and the cell cycle regulator CDKN2A has been proposed as the candidate gene. Germline mutations in this gene have been identified in about 20% of melanoma-prone families that have been studied to date. Pancreatic cancer occurs excessively in melanoma families with germline mutations in CDKN2A. Germline mutations in the cyclin-dependent kinase gene CDK4 (chromosome 12q14) have been described in three melanoma families. This finding represents a third melanoma gene but one that accounts for only a tiny fraction of all hereditary melanoma. Recently, a familial melanoma-astrocytoma syndrome has been reported. Large germline deletions of 9p21 occur in these families, with the p19 gene implicated in its pathogenesis. At present, clinical predictive genetic testing for mutations in the CDKN2A gene is available commercially, but its use has been limited by uncertainty as to how test results would affect the management of melanoma-prone family members. Currently, management recommendations include monthly skin self-examination, clinical skin examination once or twice yearly, a low threshold for simple excision of changing pigmented lesions, moderation of sun exposure, and appropriate use of sunscreens. A heritable determinant for total nevus number has been suggested by twin studies. Other data suggest the presence of a major gene responsible for "total nevus density" in melanoma-prone families. Approximately 55% of the mole phenotype in multiplex melanoma families was explained by this proposed gene. An autosomal dominant mode of inheritance has been proposed for DN, and data exist to suggest that DN may be a pleiotropic manifestation of the 1p36 familial melanoma gene. However, there clearly are melanoma-prone families that do not express the dysplastic nevus trait, and some of the families linked to CDKN2A also present with dysplastic nevi. Several studies have shown a surprisingly high prevalence of DN on the skin of family members of probands with DN. In light of the extensive evidence documenting that persons with DN (both sporadic and familial) have an increased prospective risk of melanoma, these family studies suggest that relatives of persons with DN should be examined for both DN and melanoma. Genetic determinants play a major role in the pathogenesis of normal nevi, DN, and melanoma. Identifying the molecular basis of these genetic events promises to enhance melanoma risk-reduction strategies and, ultimately, reduce melanoma-associated mortality.
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PMID:The genetics of hereditary melanoma and nevi. 1998 update. 1063 Jan 72

Risk factors for melanoma include environmental (particularly ultraviolet exposure) and genetic factors. In rare families, susceptibility to melanoma is determined by high penetrance mutations in the genes CDKN2A or CDK4, with more common, less penetrant genes also postulated. A further, potent risk factor for melanoma is the presence of large numbers of melanocytic nevi so that genes controlling nevus phenotype could be such melanoma susceptibility genes. A large Australian study involving twins aged 12 y of predominantly U.K. ancestry showed strong evidence for genetic influence on nevus number and density. We carried out essentially the same study in the U.K. to gain insight into gene-environment interactions for nevi. One hundred and three monozygous (MZ) and 118 dizygous (DZ) twin pairs aged 10-18 y were examined in Yorkshire and Surrey, U.K. Nevus counts were, on average, higher in boys (mean = 98.6) than girls (83.8) (p = 0.009) and higher in Australia (110.4) than in the U.K. (79.2, adjusted to age 12 y, p < 0.0001), and nevus densities were higher on sun-exposed sites (92 per m2) than sun-protected sites (58 per m2) (p < 0.0001). Correlations in sex and age adjusted nevus density were higher in MZ pairs (0.94, 95%CI 0.92-0.96) than in DZ pairs (0.61, 95%CI 0.49-0.72), were notably similar to those of the Australian study (MZ = 0.94, DZ = 0.60), and were consistent with high heritability (65% in the U.K., 68% in Australia). We conclude that emergence of nevi in adolescents is under strong genetic control, whereas environmental exposures affect the mean number of nevi.
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PMID:Heritability and gene-environment interactions for melanocytic nevus density examined in a U.K. adolescent twin study. 1151 14

Putative tumour suppressor genes CDKN2A and CDKN2B (on chromosome 9p21) and CDKN2A-interacting cell growth regulatory genes CDK4 and Id-1 have been demonstrated to be involved in the pathogenesis of malignant melanoma (MM). Mutation analysis of these candidate genes was performed in MM families from southern Italy with three or more affected members or two affected members and one or more relative with histologically diagnosed atypical naevus. Two CDKN2A mutations, Arg24Pro and 1-292 G>A, were observed in two (15%) families; except for CDKN2A and Id-1 polymorphisms, no sequence variations were detected in the remaining genes. Screening among 119 sporadic MM cases revealed two additional CDKN2A mutations at very low prevalences. Identification of a large shared haplotype at 9p21 in some MM families negative for CDKN germline mutations suggests that other CDKN-inactivating mechanisms may be responsible for MM predisposition or, alternatively, additional susceptibility gene(s) may be present on chromosome 9p21. Fluorescence in situ hybridization analysis of a subset of MM tissue sections seemed to indicate that the D9S171 locus may be involved in MM pathogenesis.
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PMID:Mutation analysis of candidate genes in melanoma-prone families: evidence of different pathogenetic mechanisms at chromosome 9P21. 1464 20

Atypical mole syndrome is a sporadic or an inherited condition with an increased risk of melanoma. Germline mutations in the CDKN2A, ARF, CDK4 and somatic mutations in the PTEN and BRAF genes have been associated with melanoma. In this study, we evaluated genes associated with familial and sporadic melanoma for mutations in 28 probands with the atypical mole syndrome. No sequence alterations in the coding regions or in the splice junctions of CDKN2A, ARF, CDK4, PTEN or BRAF were identified. These data suggest that genes evaluated in this study are unlikely to be candidate genes for atypical mole syndrome and support the notion that unknown susceptibility gene/s for this disease exist.
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PMID:Evaluation of germline CDKN2A, ARF, CDK4, PTEN, and BRAF alterations in atypical mole syndrome. 1566 8

Major risk factors for melanoma include many nevi, especially dysplastic nevi, fair pigmentation, freckling, poor tanning ability, and germ line mutations in the CDKN2A, CDK4, or MC1R genes. We evaluated the relationship between MC1R and melanoma risk in CDKN2A melanoma-prone families with extensive clinical and epidemiologic data. We studied 395 subjects from 16 American CDKN2A families. Major melanoma risk factors were assessed by clinical examination or questionnaire; MC1R was sequenced. Odds ratios were estimated by unconditional and conditional logistic regression models. We examined the distribution of MC1R variants and median ages at melanoma diagnosis in multiple primary melanoma (MPM) and single primary melanoma (SPM) patients. Presence of multiple MC1R variants was significantly associated with melanoma, even after adjustment for major melanoma risk factors. All 40 MPM patients had at least one MC1R variant; 65% of MPM patients versus only 17% of SPM patients had at least two MC1R variants (P < 0.0001). For all 69 melanoma patients combined, as well as the 40 MPM patients, there was a statistically significant decrease in median age at diagnosis as numbers of MC1R variants increased (P = 0.010 and P = 0.008, respectively). In contrast, no significant reduction in age at melanoma diagnosis was observed for SPM patients (P = 0.91). The current study suggests that the presence of multiple MC1R variants is associated with the development of multiple melanoma tumors in patients with CDKN2A mutations. Additional studies are needed to confirm these findings and to explore the mechanisms that may contribute to this relationship.
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PMID:Association of MC1R variants and risk of melanoma in melanoma-prone families with CDKN2A mutations. 1628 65

A significantly increased susceptibility to melanoma may manifest as a family history of melanoma (plus or minus pancreatic cancer), the development of multiple primary tumors, or melanoma in the context of numerous and clinically atypical moles (the atypical mole syndrome). In families, increased susceptibility may occur as a result of the inheritance of mutations at the CDKN2A locus or in the CDK4 gene. We describe what is known about these genes and discuss the implications for genetic counseling and gene testing. Lower levels of risk are associated with genetically determined pigmentary variation within populations. This variation is attributable to inheritance of variants in the MC1R gene and putatively other genes such as OCA2, which is discussed. Melanoma is causally related to sun exposure in the majority of patients, although the patterns of sun exposure, which are most important, remain controversial. The role of risk estimation for individuals in giving advice about sun exposure is considered.
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PMID:Genetics: what advice for patients who present with a family history of melanoma? 1808 68

Recent studies have indicated an increasing incidence of melanoma worldwide. Although UV signature mutations are found rarely in melanoma cells, there is some evidence that intense intermittent exposure to sunlight can induce melanocyte tumorigenesis, and this is also observed after UV irradiation in some animals. The purpose of this paper is to review some of the most important mechanisms involved in the pathogenesis of this tumor. Genetic studies showed the familiar melanoma is linked to the mutation or deletion of the suppressor gene CDKN2A, and perhaps to CDK4. Studies showed that BRAF mutation is frequent in primary and metastatic melanoma cells but also in naevocytic nevi. This mutation activates the RAF/MEK pathway. Exposure to UV radiation induces immunosuppression. Recent investigations showed that chemokines, angiogenesis, metalloproteinases can play a role in the mechanism of metastasis. In spite of these advances the initiating events are still not completely understood. In conclusion, the pathogenesis of melanoma is very complex because numerous genetic and epigenetic factors are implicated in its development and progression, but some of the showed mechanisms can be targets for new therapies.
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PMID:Molecular and genetic mechanisms in melanoma. 1913 18

Malignant melanoma, a potentially lethal skin neoplasm, is characterized by a complex and heterogeneous etiology. Both incidences and deaths associated with melanoma are increasing in Caucasian populations. While exposure to ultraviolet radiation through sun-exposure is the major risk factor; the host factors including skin type and number of moles are critical in predisposition. The CDKN2A is a high penetrance melanoma susceptibility gene as carriers of the mutations are predisposed to the disease within familial settings. The gene is also somatically altered to varying degrees in sporadic melanoma. The CDK4 gene due to occurrence of activation mutations in a few families worldwide represents another melanoma susceptibility locus. The variants within the melanocortin receptor 1 (MC1R) gene, which encodes a melanocyte specific surface receptor with a key role in pigmentation, are associated with high risk phenotypes and increased risk of melanoma. Melanoma tumors are characterized by activation of the RAS-RAF-MEK-ERK pathway through either autocrine growth factor stimulation or oncogenic mutations in the B-RAF or N-RAS genes. Somatic mutations in the B-RAF gene are complemented by those in the N-RAS gene and represent the major genetic alterations. The mutations in the B-RAF gene in melanoma due to occurrence in melanocytic nevi represent early events that additionally require loss of cell cycle inhibitors like CDKN2A for melanoma progression and development. The sequence of events points to the cooperative collaboration between different genetic pathways in tumor development that can be and are being used as targets for developing specific therapeutic agents.
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PMID:Malignant melanoma--a genetic overview. 2009 96


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