RESUMO
Increased genetic risk for melanoma can occur in the context of germline pathogenic variants in high-penetrance genes, such as CDKN2A and CDK4, risk variants in low- to moderate-penetrance genes (MC1R and MITF), and possibly due to variants in emerging genes, such as ACD, TERF2IP, and TERT. We aimed to identify germline variants in high- and low- to moderate-penetrance melanoma risk genes in Brazilian patients with clinical criteria for familial melanoma syndrome. We selected patients with three or more melanomas or melanoma patients from families with three tumors (melanoma and pancreatic cancer) in first- or second-degree relatives. Genetic testing was performed with a nine-gene panel (ACD, BAP1, CDK4, CDKN2A, POT1, TERT, TERF2IP, MC1R, and MITF). In 36 patients, we identified 2 (5.6%) with germline pathogenic variants in CDKN2A and BAP1 and 4 (11.1%) with variants of uncertain significance in the high-penetrance genes. MC1R variants were found in 86.5%, and both red hair color variants and unknown risk variants were enriched in patients compared to a control group. The low frequency of germline pathogenic variants in the high-penetrance genes and the high prevalence of MC1R variants found in our cohort show the importance of the MC1R genotype in determining the risk of melanoma in the Brazilian melanoma-prone families.
Assuntos
Melanoma , Neoplasias Cutâneas , Humanos , Brasil/epidemiologia , Predisposição Genética para Doença , Melanoma/epidemiologia , Melanoma/genética , Melanoma/patologia , Neoplasias Cutâneas/epidemiologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Testes Genéticos , Mutação em Linhagem Germinativa , Inibidor p16 de Quinase Dependente de Ciclina/genética , Receptor Tipo 1 de Melanocortina/genéticaRESUMO
In domestic camelids, fleece color is an essential characteristic because it defines the direction of production. Variants were determined in the MC1R gene that showed a relationship with coat color in alpacas and llamas at the level of the coding region. This report sequenced the MC1R gene from 290 alpacas (142 white, 84 black, 50 brown, and 14 light fawn), five brown llamas, nine vicuñas, and three guanacos to analyze the association between coat color and the MC1R gene among South American camelids. A total of nineteen polymorphisms were identified. Seven polymorphisms were significant; three of them were of nonsynonymous type (c.82A > G, c.376G > A, and c.901C > T), two were of synonymous type (c.126 T > C and c.933G > A), one was in the promoter region (-42C > G), and one was in the 3' UTR (+5T > C). More polymorphisms were found in domestic camelids than in wild camelids. Besides polymorphism, the association of polymorphisms might cause white and dark pigmentation in the fleece of South American camelids. In addition, the MC1R protein would answer the pigmentation in alpacas.
Assuntos
Camelídeos Americanos , Cor de Cabelo , Receptor Tipo 1 de Melanocortina , Animais , Sequência de Bases , Camelídeos Americanos/genética , Cor de Cabelo/genética , Polimorfismo de Nucleotídeo Único , Receptor Tipo 1 de Melanocortina/genética , América do SulRESUMO
The melanocortin-1 receptor (MC1R) is one of the key proteins involved in the regulation of melanin production and several polymorphisms have been associated with different phenotypes of skin and hair color in human and nonhuman species. Most of the knowledge is centered on more homogeneous populations and studies involving an admixed group of people should be encouraged due to the great importance of understanding the human color variation. This work evaluates the MC1R diversity and the possible impacts of MC1R variants in an admixed sample population of Rio de Janeiro, Brazil, which is a product of Native American, African, and European miscegenation. Sequencing of complete coding region and part of the 3´UTR of MC1R gene identified 31 variants including one insertion and three novel synonymous substitutions in sample population grouped according to skin, hair and eye pigmentation levels. In nonmetric multidimensional scaling analysis (NMDS), three main clusters were identified, in which the Brazilian dark skin group remained in the African cluster whereas the intermediate and the light skin color phenotype in the European one. None gathered with Asians since their immigration to Brazil was a recent event. In silico analyses demonstrated that Cys35Tyr, Ile155Thr and Pro256Ser, found in our population, have a negative effect on receptor function probably due to changes on the receptor structure. Notably, Cys35Tyr mutation could potentially impair agonist binding. Altogether, this work contributes to the understanding of the genetic background of color variation on an admixed population and gives insights into the damaging effects of MC1R variants.
Assuntos
Cor de Cabelo , Receptor Tipo 1 de Melanocortina , Brasil , Variação Genética , Cor de Cabelo/genética , Humanos , Fenótipo , Polimorfismo Genético , Receptor Tipo 1 de Melanocortina/genéticaRESUMO
Skin cancer risk information based on melanocortin-1 receptor (MC1R) variants could inform prevention and screening recommendations for Hispanics, but limited evidence exists on the impact of MC1R variants in Hispanic populations. We studied Hispanic subjects, predominately of Puerto Rican heritage, from Tampa, Florida, US, and Ponce, PR. Blood or saliva samples were collected by prospective recruitment or retrieved from biobanks for genotyping of MC1R variants and ancestry informative markers. Participant demographic and self-reported phenotypic information was collected via biobank records or questionnaires. We determined associations of MC1R genetic risk categories and phenotypic variables and genetic ancestry. Over half of participants carried MC1R variants known to increase risk of skin cancer, and there was diversity in the observed variants across sample populations. Associations between MC1R genetic risk groups and some pigmentation characteristics were identified. Among Puerto Ricans, the proportion of participants carrying MC1R variants imparting elevated skin cancer risk was consistent across quartiles of European, African, and Native American genetic ancestry. These findings demonstrate that MC1R variants are important for pigmentation characteristics in Hispanics and that carriage of high risk MC1R alleles occurs even among Hispanics with stronger African or Native American genetic ancestry.
Assuntos
Alelos , Hispânico ou Latino/genética , Polimorfismo Genético , Receptor Tipo 1 de Melanocortina/genética , Neoplasias Cutâneas/genética , Pigmentação da Pele/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Porto RicoRESUMO
A molecular genetic protocol for distinguishing pure and hybrid South American camelids was developed to provide strong, quantifiable, and unbiased species identification. We detail the application of the approach in the context of a criminal case in the Andes Mountains of central Chile where the defendants were alleged to have illegally hunted three wild guanacos (Lama guanicoe), as opposed to hybrid domestic llama (Lama glama)/wild guanaco crosses, which are unregulated. We describe a workflow that differentiates among wild, domestic and hybrid South American camelids (Lama versus Vicugna) based on mitochondrial cytochrome b genetic variation (to distinguish between Lama and Vicugna), and MC1R and exon 4 variation of the ASIP gene (to differentiate wild from domestic species). Additionally, we infer the population origin and sex of each of the three individuals from a panel of 15 autosomal microsatellite loci and the presence or absence of the SRY gene. Our analyses strongly supported the inference that the confiscated carcasses corresponded with 2 male and 1 female guanacos that were hunted illegally. Statistical power analyses suggested that there was an extremely low probability of misidentifying domestic camelids as wild camelids (an estimated 0 % Type I error rate), or using more conservative approached a 1.17 % chance of misidentification of wild species as domestic camelids (Type II error). Our case report and methodological and analytical protocols demonstrate the power of genetic variation in coat color genes to identify hybrids between wild and domestic camelid species and highlight the utility of the approach to help combat illegal wildlife hunting and trafficking.
Assuntos
Pelo Animal , Animais Domésticos/genética , Animais Selvagens/genética , Camelidae/genética , Genética Forense/métodos , Variação Genética , Proteína Agouti Sinalizadora/genética , Animais , Conservação dos Recursos Naturais/legislação & jurisprudência , Crime/legislação & jurisprudência , Citocromos b/genética , DNA Mitocondrial/genética , Éxons , Feminino , Genes sry , Masculino , Repetições de Microssatélites , Receptor Tipo 1 de Melanocortina/genética , Análise para Determinação do Sexo , América do SulRESUMO
BACKGROUND: The Melanocortin 1 Receptor (MC1R) contributes to pigmentation, an important risk factor for developing melanoma. Evaluating SNPs in MC1R and association with race/ethnicity, skin type, and perceived cancer risk in a New Mexico (NM) population will elucidate the role of MC1R in a multicultural population. METHODS: We genotyped MC1R in 191 NMs attending a primary care clinic in Albuquerque. We obtained individuals' self-identified race/ethnicity, skin type, and perceived cancer risk. We defined genetic risk as carriage of any one or more of the nine most common SNPs in MC1R. RESULTS: We found that one MC1R SNP, R163Q (rs885479), was identified in 47.6% of self-identified Hispanics and 12.9% of non-Hispanic whites (NHW), making Hispanics at higher "genetic risk" (as defined by carrying one of the MC1R common variants). When we deleted R163Q from analyses, Hispanics were no longer at higher genetic risk (33.3%) compared with NHW (48.3%), consistent with melanoma rates, tanning ability, and lower perceived risk. Hispanics had a perceived risk significantly lower than NHW and a nonsignificant better tanning ability than NHW. CONCLUSIONS: The R163Q variant in MC1R may not be a risk factor for melanoma among NM Hispanics. This suggestion points to the need to carefully interpret genetic risk factors among specific populations. IMPACT: Genetic risk cannot be extrapolated from Northern European populations directly to non-European populations.
Assuntos
Receptor Tipo 1 de Melanocortina/genética , Variação Genética , Genótipo , Humanos , New MexicoRESUMO
The objective of the present study was to investigate the effect of single nucleotide polymorphism (SNP) of the melanocortin 1 receptor (MC1R) gene on plumage coloration in mule ducks. PCR-high-resolution melting analysis (PCR-HRM) and DNA sequencing were used to identify the SNP variability of the MC1R gene in white common ducks. Three non-synonymous SNP (MC1R gene exon 1, c.52G>A, c.376G>A, and c.409G>A) were identified in white Tsaiya ducks. Mating test (white Tsaiya ducks × white Muscovy drakes) in combination with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to investigate the effect of non-synonymous SNP of different maternal lines on plumage coloration in mule ducks. Genotyping results from 58 white Tsaiya ducks revealed the significant associations between genetic variations (c.52G>A, c.376A>G, and c.409G>A) and plumage color in two maternal populations. After genotyping of 266 mule ducks, these three non-synonymous SNP identified in white Tsaiya ducks were significantly associated with plumage color of mule ducks. Therefore, the polymorphisms of MC1R gene at c.52G>A, c.376A>G, and c.409G>A in white Tsaiya duck could be used in marker-assisted selection to improve the plumage color of mule ducks.(AU)
Assuntos
Animais , Polimorfismo Genético , Receptor Tipo 1 de Melanocortina/genética , Patos/fisiologia , Reação em Cadeia da Polimerase/métodosRESUMO
The melanocortin-1 receptor gene is the most widely-used marker for the investigation of the genetic determination of melanic plumage patterns. Studies of a number of wild bird species have shown an association between non-synonymous mutations of the MC1R gene and the presence of melanic variants. The genus Antilophia (Pipridae) includes only two manakin species (A. galeata and A. bokermanni), which are distinguished primarily by the differences in the pattern of melanic coloration of the plumage of the mantle in the adult males. In A. galeata, this plumage is black, while in A. bokermanni, it is predominantly white. This study investigates the possible association between mutations of the MC1R marker and the variation in plumage coloration observed in the two species. The MC1R sequences of the two species was analyzed, and the observed nucleotide variation was compared. Six polymorphic sites were identified, representing seven distinct genotypes. Five of these polymorphic mutations were non-synonymous, but were not related to the different phenotypes. Neutral evolution and the absence of any systematic association between the variants of the MC1R and plumage coloration in the Antilophia species indicate that alternative mechanisms regulate the expression of the coloration of the plumage in the adult males.