Project description:Genetic susceptibility to nevi may affect the risk of developing melanoma, since common and atypical nevi are the main host risk factors implicated in the development of cutaneous melanoma. Recent genome-wide studies defined a melanoma polygenic risk score based on variants in genes involved in different pathways, including nevogenesis. Moreover, a predisposition to nevi is a hereditary trait that may account for melanoma clustering in some families characterized by cases with a high nevi density. On the other hand, familial melanoma aggregation may be due to a Mendelian inheritance of high/moderate-penetrance pathogenic variants affecting melanoma risk, regardless of the nevus count. Based on current knowledge, this review analyzes the complex interplay between nevi and melanoma predisposition in a familial context. We review familial melanoma, starting from Whiteman's divergent pathway model to overall melanoma development, distinguishing between nevi-related (cases with a high nevus count and a high polygenic risk score) and nevi-resistant (high/moderate-penetrance variant-carrier cases) familial melanoma. This distinction could better direct future research on genetic factors useful to identify high-risk subjects.
Project description:BACKGROUND: Genome-wide association studies prove to be a powerful approach to identify the genetic basis of different human diseases. We studied the relationship between seven diseases characterized in a previous genome-wide association study by the Wellcome Trust Case Control Consortium. Instead of doing a horizontal association of SNPs to diseases, we did a vertical analysis of disease associations by comparing the genetic similarities of diseases. Our analysis was carried out at four levels - the nucleotide level (SNPs), the gene level, the protein level (through protein-protein interaction network), and the phenotype level. RESULTS: Our results show that Crohn's disease, rheumatoid arthritis, and type 1 diabetes share evidence of genetic associations at all levels of analysis, offering strong molecular support for the current grouping of the diseases. On the other hand, coronary artery disease, hypertension, and type 2 diabetes, despite being considered as a natural group with potential aetiological overlap, do not show any evidence of shared genetic basis at all levels. CONCLUSION: Our study is a first attempt on mining of GWA data to examine genetic associations between different diseases. The positive result is apparently not a coincidence and hence demonstrates the promising use of our approach.
Project description:We conducted a genome-wide association study on the number of melanocytic nevi reported by 9136 individuals of European ancestry, with follow-up replication in 3581 individuals. We identified the nidogen 1 (NID1) gene on 1q42 associated with nevus count (two linked single nucleotide polymorphisms with r(2) > 0.9: rs3768080 A allele associated with reduced count, P = 6.5 × 10(-8); and rs10754833 T allele associated with reduced count, P = 1.5 × 10(-7)). We further determined that the rs10754833 [T] was associated with a decreased melanoma risk in 2368 melanoma cases and 7432 controls [for CT genotype: odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.75-0.99, P = 0.04; for TT genotype: OR = 0.84, 95% CI = 0.71-0.98, P = 0.03]. Expression level of the NID1 locus was 2-fold higher for the rs10754833 T allele carriers than that with the CC genotype (P = 0.017) in the 87 HapMap CEU cell lines. The NID1 gene is a biologically plausible locus for nevogenesis and melanoma development, with decreased expression levels of NID1 in benign nevi (P = 3.5 × 10(-6)) and in primary melanoma (P = 4.6 × 10(-4)) compared with the normal skin.
Project description:Cutaneous malignancies, especially malignant melanoma, exhibit great genetic heterogeneity. As a result, some individuals and families have particularly increased risk due to genetic predisposition to the disease. The susceptibility alleles range from rarely occurring, heritable, high-risk variants to ubiquitously occurring low-risk variants. Although until now the focus has been mostly towards the familial high-risk genes, the development of genome-wide association studies has uncovered a number of moderate- to low-risk predisposition alleles. The ability to specifically identify genetic variation associated with visible pigmentation traits and disease risk has provided a much richer view of the genetics of cutaneous malignancies. In this review, we provide an update on the recently identified risk loci. Existing clinical data, combined with vast genome information, will provide a better understanding of the biology of disease, and increased accuracy in risk prediction.
Project description:According to the prevailing multistep model of melanoma development, oncogenic BRAF or NRAS mutations are crucial initial events in melanoma development. It is not known whether melanocytic nevi that are found in association with a melanoma are more likely to carry BRAF or NRAS mutations than uninvolved nevi. By laser microdissection we were able to selectively dissect and genotype cells either from the nevus or from the melanoma part of 46 melanomas that developed in association with a nevus. In 25 cases we also genotyped a control nevus of the same patients. Available tissue was also immunostained using the BRAF(V600E)-mutation specific antibody VE1. The BRAF(V600E) mutation was found in 63.0% of melanomas, 65.2% of associated nevi and 50.0% of control nevi. No significant differences in the distribution of BRAF or NRAS mutations could be found between melanoma and associated nevi or between melanoma associated nevi and control nevi. In concordant cases immunohistochemistry showed a higher expression (intensity of immunohistochemistry) of the mutated BRAF(V600E)-protein in melanomas compared to their associated nevi. In this series the presence of a BRAF- or NRAS mutation in a nevus was not associated with the risk of malignant transformation. Our findings do not support the current traditional model of stepwise tumor progression.
Project description:BACKGROUND:Genome wide association studies (GWAS) have proven useful as a method for identifying genetic variations associated with diseases. In this study, we analyzed GWAS data for 61 diseases and phenotypes to elucidate common associations based on single nucleotide polymorphisms (SNP). The study was an expansion on a previous study on identifying disease associations via data from a single GWAS on seven diseases. METHODOLOGY/PRINCIPAL FINDINGS:Adjustments to the originally reported study included expansion of the SNP dataset using Linkage Disequilibrium (LD) and refinement of the four levels of analysis to encompass SNP, SNP block, gene, and pathway level comparisons. A pair-wise comparison between diseases and phenotypes was performed at each level and the Jaccard similarity index was used to measure the degree of association between two diseases/phenotypes. Disease relatedness networks (DRNs) were used to visualize our results. We saw predominant relatedness between Multiple Sclerosis, type 1 diabetes, and rheumatoid arthritis for the first three levels of analysis. Expected relatedness was also seen between lipid- and blood-related traits. CONCLUSIONS/SIGNIFICANCE:The predominant associations between Multiple Sclerosis, type 1 diabetes, and rheumatoid arthritis can be validated by clinical studies. The diseases have been proposed to share a systemic inflammation phenotype that can result in progression of additional diseases in patients with one of these three diseases. We also noticed unexpected relationships between metabolic and neurological diseases at the pathway comparison level. The less significant relationships found between diseases require a more detailed literature review to determine validity of the predictions. The results from this study serve as a first step towards a better understanding of seemingly unrelated diseases and phenotypes with similar symptoms or modes of treatment.
Project description:Assessment of mutation on expression levels Transcriptomic profile of a matched primary and metastatic acral melanoma One Primary and one metastatic acral melanoma transcript expression were assayed (no matched normal)
Project description:Chromosome 9p21 has been implicated in the pathogenesis of cutaneous malignant melanoma (CMM). In addition to CDKN2A, the major known high-risk susceptibility gene for CMM, recent studies suggest that other 9p21 genes may be involved in melanoma/nevi development. To identify 9p21 variants that influence susceptibility to CMM and number of nevi in CMM-prone families with and without CDKN2A mutations, we analyzed 562 individuals (183 CMM) from 53 families (23 CDKN2A+, 30 CDKN2A-) for 233 tagging SNPs in 21 genes at 9p21. Single SNP- and gene-based regression analyses were used to assess the risk of CMM, nevi count, skin complexion, and tanning ability associated with these SNPs and genes. We found that SNP rs7023329 in the MTAP gene was associated with number of nevi (P (trend) = 0.003) confirming a recent finding by a genome-wide association study. In addition, three SNPs in the ACO1 gene, rs7855483 (P (trend) = 0.002), rs17288067 (P (trend) = 0.0009), and rs10813813 (P (trend) = 0.005), showed the strongest associations with CMM risk. None of the examined 9p21 SNPs was associated with skin complexion, whereas two SNPs, rs10964862 in IFNW1 (P (trend) = 0.003), and rs13290968 in TUSC1 (P (trend) = 0.0006), were associated with tanning ability. Gene-based analyses suggested that the ACO1 gene was significantly associated with CMM (P = 0.0004); genes IFNW1 (P = 0.002) and ACO1 (P = 0.0002) were significantly associated with tanning ability. Our findings are consistent with recent proposals that additional 9p21 genes may contribute to CMM susceptibility in CMM-prone families. These genetic variants may, at least partially, exert their effects through nevi and tanning ability.