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Origone P.,University of Genoa | Gargiulo S.,University of Genoa | Mastracci L.,University of Genoa | Ballestrero A.,University of Genoa | And 13 more authors.
Gastric Cancer | Year: 2013

Purpose: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract. Most (80 %) contain activating mutations in the KIT receptor tyrosine kinase, roughly 10 % in platelet-derived growth factor receptor-alpha (PDGFRA). In a small subset, BRAF mutations are an alternative molecular pathway. GISTs respond well to imatinib, but low response is seen in patients with wild-type KIT or PDGFRA. Resistance has also been reported as a result of mutations in downstream effectors such as BRAF. Methods: We provide here a molecular characterization of a series of primary GISTs from Italian patients. Of 121 GIST cases diagnosed between 2000 and 2012, 83 were evaluated by PCR amplification and direct sequencing for mutations in KIT exons 8, 9, 11, 13, and 17, PDGFRA exons 12, 14, and 18, and BRAF exon 15. Eighty-one GISTs also underwent K-RAS testing. Results: Sixty-four GISTs were positive: 55 had mutations in KIT and 9 in PDGFRA; 16 patients were mutation negative. Three samples came from NF1 patients and were KIT- and PDGFRA negative. Overall, we identified six novel mutations in KIT (p.K550-M552delinsL, p.Q556-W557delinsG p.Q556-G575del, p.W557-V559delinsQ p.P573-R588dup, p.G592-K593dup) and one novel mutation in PDGFRA (p.D842-N848delinsVDV), thus contributing to widening the spectrum of known mutations in GIST tumors and confirming the most frequently altered regions underlying GIST development. Conclusions: Among the 64 KIT- and PDGFRA-positive sporadic patients in our series, no BRAF or KRAS mutations were identified, suggesting that co-occurrence of these mutations is likely to be rare in the northwestern Italian population and not a frequent cause of primary resistance to imatinib in KIT-positive GIST patients. © 2013 The International Gastric Cancer Association and The Japanese Gastric Cancer Association. Source

Ghiorzo P.,University of Genoa | Ghiorzo P.,Laboratory of Genetics of Rare Hereditary Cancers | Pastorino L.,University of Genoa | Pastorino L.,Laboratory of Genetics of Rare Hereditary Cancers | And 10 more authors.
Pigment Cell and Melanoma Research | Year: 2013

A French and an Australian study have recently identified a rare germline functional variant in the microphthalmia-associated transcription factor (MITF) (E318K) that predisposes to familial and sporadic melanoma and to renal cell carcinoma (RCC), showing a new link between two tumour types with different risk factors and between deregulated sumoylation and cancer. The aim of this study was to test the prevalence of the MITF E318K mutation in 667 Italian melanoma patients. We observed significant associations between histological subtypes and family cancer history. Carriers exhibited a nearly threefold higher risk of developing melanoma compared with controls. Carriers were also more likely to have developed multiple primary melanomas (6.40-fold), compared with wt patients. Carriers with a personal and/or family history of pancreatic cancer and kidney cancer had a nearly 31- and eightfold higher risk of developing melanoma compared with wt patients. Our findings further support MITF as a medium-penetrance melanoma susceptibility gene, highlight a potential association with histological subtypes and suggest that MITF may predispose to pancreatic cancer. © 2012 John Wiley & Sons A/S. Source

Demenais F.,French Institute of Health and Medical Research | Demenais F.,University Paris Diderot | Mohamdi H.,French Institute of Health and Medical Research | Mohamdi H.,University Paris Diderot | And 42 more authors.
Journal of the National Cancer Institute | Year: 2010

Background Carrying the cyclin-dependent kinase inhibitor 2A (CDKN2A) germline mutations is associated with a high risk for melanoma. Penetrance of CDKN2A mutations is modified by pigmentation characteristics, nevus phenotypes, and some variants of the melanocortin-1 receptor gene (MC1R), which is known to have a role in the pigmentation process. However, investigation of the associations of both MC1R variants and host phenotypes with melanoma risk has been limited. Methods We included 815 CDKN2A mutation carriers (473 affected, and 342 unaffected, with melanoma) from 186 families from 15 centers in Europe, North America, and Australia who participated in the Melanoma Genetics Consortium. In this family-based study, we assessed the associations of the four most frequent MC1R variants (V60L, V92M, R151C, and R160W) and the number of variants (1, ≥2 variants), alone or jointly with the host phenotypes (hair color, propensity to sunburn, and number of nevi), with melanoma risk in CDKN2A mutation carriers. These associations were estimated and tested using generalized estimating equations. All statistical tests were two-sided. Results Carrying any one of the four most frequent MC1R variants (V60L, V92M, R151C, R160W) in CDKN2A mutation carriers was associated with a statistically significantly increased risk for melanoma across all continents (1.24 × 10-6 ≤ P ≤. 0007). A consistent pattern of increase in melanoma risk was also associated with increase in number of MC1R variants. The risk of melanoma associated with at least two MC1R variants was 2.6-fold higher than the risk associated with only one variant (odds ratio = 5.83 [95% confidence interval = 3.60 to 9.46] vs 2.25 [95% confidence interval = 1.44 to 3.52]; Ptrend = 1.86 × 10-8). The joint analysis of MC1R variants and host phenotypes showed statistically significant associations of melanoma risk, together with MC1R variants (.0001 ≤ P ≤. 04), hair color (.006 ≤ P ≤. 06), and number of nevi (6.9 × 10-6 ≤ P ≤. 02). Conclusions Results show that MC1R variants, hair color, and number of nevi were jointly associated with melanoma risk in CDKN2A mutation carriers. This joint association may have important consequences for risk assessments in familial settings. © 2010 The Author. Source

Yang X.R.,U.S. National Institutes of Health | Brown K.,U.S. National Institutes of Health | Landi M.T.,U.S. National Institutes of Health | Ghiorzo P.,University of Genoa | And 13 more authors.
Pigment Cell and Melanoma Research | Year: 2012

Copy number variations (CNVs) have been shown to contribute substantially to disease susceptibility in several inherited diseases including cancer. We conducted a genome-wide search for CNVs in blood-derived DNA from 79 individuals (62 melanoma patients and 17 spouse controls) of 30 high-risk melanoma-prone families without known segregating mutations using genome-wide comparative genomic hybridization (CGH) tiling arrays. We identified a duplicated region on chromosome 4q13 in germline DNA of all melanoma patients in a melanoma-prone family with three affected siblings. We confirmed the duplication using quantitative PCR and a custom-made CGH array design spanning the 4q13 region. The duplicated region contains 10 genes, most of which encode CXC chemokines. Among them, CXCL1 (melanoma growth-stimulating activity α) and IL8 (interleukin 8) have been shown to stimulate melanoma growth in vitro and in vivo. Our data suggest that the alteration of CXC chemokine genes may confer susceptibility to melanoma. Published 2012. This article is a US Government work and is in the public domain in the USA. Source

Lang J.M.,University of Toronto | Shennan M.,University of Toronto | Njauw J.C.-N.,Massachusetts General Hospital | Luo S.,Massachusetts General Hospital | And 14 more authors.
Journal of Investigative Dermatology | Year: 2011

The presence of recurrent high-risk mutations in cyclin-dependent kinase inhibitor 2A/cyclin-dependent kinase 4 (CDKN2A/CDK4) among melanoma-prone families suggests that a high-throughput, multiplex assay could serve as an effective initial screening tool. To this end, we have developed a multiplex bead-based assay for high-throughput CDKN2A/CDK4 genotyping in the context of familial melanoma. Genomic DNA from 1,603 subjects (1,005 in training set and 598 in validation set) were amplified by multiplex PCR using five CDKN2A/CDK4 primer sets followed by multiplex allele-specific primer extension for 39 distinct germline variants. The products were then sorted and analyzed using the Luminex xMAP system. Genotypes were compared with previously determined sequence data. In the Toronto training cohort, all 145 samples with known variants were detected by the bead assay (100% concordance). Analysis of the 598 samples from the GenoMEL validation set led to identification of 150/155 expected variants (96.77%). Overall, the bead assay correctly genotyped 1,540/1,603 (96.07%) of all individuals in the study and 1,540/1,545 (99.68%) of individuals whose variants were represented in the probe set. Out of a total of 62,517 allelic calls, 62,512 (99.99%) were correctly assigned. The multiplex bead-based assay is an accurate method for genotyping CDKN2A/CDK4 variants and is potentially useful in genotyping low-to-moderate melanoma risk single-nucleotide polymorphisms. © 2011 The Society for Investigative Dermatology. Source

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