Germline ATM variants predispose to melanoma: a joint analysis across the GenoMEL and MelaNostrum consortia.

PURPOSE: Ataxia-Telangiectasia Mutated (ATM) has been implicated in the risk of several cancers, but establishing a causal relationship is often challenging. Although ATM single-nucleotide polymorphisms have been linked to melanoma, few functional alleles have been identified. Therefore, ATM impact on melanoma predisposition is unclear. METHODS: From 22 American, Australian, and European sites, we collected 2,104 familial, multiple primary (MPM), and sporadic melanoma cases who underwent ATM genotyping via panel, exome, or genome sequencing, and compared the allele frequency (AF) of selected ATM variants classified as loss-of-function (LOF) and variants of uncertain significance (VUS) between this cohort and the gnomAD non-Finnish European (NFE) data set. RESULTS: LOF variants were more represented in our study cohort than in gnomAD NFE, both in all (AF = 0.005 and 0.002, OR = 2.6, 95% CI = 1.56-4.11, p < 0.01), and familial + MPM cases (AF = 0.0054 and 0.002, OR = 2.97, p < 0.01). Similarly, VUS were enriched in all (AF = 0.046 and 0.033, OR = 1.41, 95% CI = 1.6-5.09, p < 0.01) and familial + MPM cases (AF = 0.053 and 0.033, OR = 1.63, p < 0.01). In a case-control comparison of two centers that provided 1,446 controls, LOF and VUS were enriched in familial + MPM cases (p = 0.027, p = 0.018). CONCLUSION: This study, describing the largest multicenter melanoma cohort investigated for ATM germline variants, supports the role of ATM as a melanoma predisposition gene, with LOF variants suggesting a moderate-risk.

Intergenic disease-associated regions are abundant in novel transcripts.

BACKGROUND: Genotyping of large populations through genome-wide association studies (GWAS) has successfully identified many genomic variants associated with traits or disease risk. Unexpectedly, a large proportion of GWAS single nucleotide polymorphisms (SNPs) and associated haplotype blocks are in intronic and intergenic regions, hindering their functional evaluation. While some of these risk-susceptibility regions encompass cis-regulatory sites, their transcriptional potential has never been systematically explored. RESULTS: To detect rare tissue-specific expression, we employed the transcript-enrichment method CaptureSeq on 21 human tissues to identify 1775 multi-exonic transcripts from 561 intronic and intergenic haploblocks associated with 392 traits and diseases, covering 73.9 Mb (2.2%) of the human genome. We show that a large proportion (85%) of disease-associated haploblocks express novel multi-exonic non-coding transcripts that are tissue-specific and enriched for GWAS SNPs as well as epigenetic markers of active transcription and enhancer activity. Similarly, we captured transcriptomes from 13 melanomas, targeting nine melanoma-associated haploblocks, and characterized 31 novel melanoma-specific transcripts that include fusion proteins, novel exons and non-coding RNAs, one-third of which showed allelically imbalanced expression. CONCLUSIONS: This resource of previously unreported transcripts in disease-associated regions ( http://gwas-captureseq.dingerlab.org ) should provide an important starting point for the translational community in search of novel biomarkers, disease mechanisms, and drug targets.

Melanocyte transformation requires complete loss of all pocket protein function via a mechanism that mitigates the need for MAPK pathway activation.

Deregulation of p16INK4A is a critical event in melanoma susceptibility and progression. It is generally assumed that the major effect of loss of p16 function is mediated through the CDK-cyclin pathway via its influence on the pocket protein (PP) pRb. However, there are also two other PPs, p107 and p130, which, when phosphorylated by CDK-cyclin complexes, play a role in permitting cell progression. Cohorts of mice carrying melanocyte-specific knockouts (KOs) of various combinations of the three PPs were generated. Mice null for pRb, p107, p130 or any combination of double mutants did not develop melanoma. Surprisingly, melanocyte-specific loss of all three PPs facilitated melanoma development (median age of onset 308 days, penetrance 40% at 1 year). Tumorigenesis was exacerbated by Trp53 co-deletion (median age of onset 275 days, penetrance 82% at 1 year), with cell culture studies indicating that this difference may result from the apoptotic role of Trp53. Melanomas in PP;Trp53-deficient mice lacked either Ras or Braf mutations, and hence developed in the absence of constitutive MAPK pathway activation. The lag period between induction of total PP or PP/Trp53 KO and melanoma development indicates that additional genetic or epigenetic alterations may account for neoplastic progression. However, exome sequencing of PP;Trp53 KO melanomas failed to reveal any additional recurrent driver mutations. Analysis of the putative mutation signature of the PP;Trp53 KO melanomas suggests that melanocytes are primed for transformation via a mutagenic mechanism involving an excess of T>G substitutions, but not involving a preponderance of C>T substitutions at CpG sites, which is the case for most spontaneous cancers not driven by a specific carcinogen. In sum, deregulation of all three PPs appears central to neoplastic progression for melanoma, and the customary reference to the p16INKA/CDK4/pRB pathway may no longer be accurate; all PPs are potentially critical targets of CDK-cyclins in melanoma.

Survival outcomes in patients with multiple primary melanomas.

BACKGROUND: A substantial number of melanoma patients will develop multiple primary melanomas (MPM). Currently, little is known about the impact of MPM on survival. OBJECTIVE: We aimed to determine whether melanoma survival is worse for patients with MPM compared to those with a single invasive primary melanoma (SPM). MATERIALS AND METHODS: A cohort study was conducted. Patients were sourced from an Australian population, with follow-up information collected retrospectively from registry data. Melanoma-specific survival analysis was performed to find associated variables after adjustment for known prognostic factors, using four different models, each selecting a different index melanoma lesion. RESULTS: 1068 stage I and II melanoma patients were followed up for a median of 24.4 years. MPM was found in 17.8% of the cohort (190 patients), more likely among males and older age groups. Other clinicopathological parameters were similar between the MPM and SPM (878 patients) cohorts. After adjustment for age, sex and Breslow thickness, MPM was a hazard for death from melanoma, across all models, reaching significance when considering the last invasive lesion as the index melanoma (HR = 2.76, P = 0.017). CONCLUSION: Patients with multiple invasive lesions seem more at risk of death from melanoma, independent of known prognostic factors.

A recurrent germline BAP1 mutation and extension of the BAP1 tumor predisposition spectrum to include basal cell carcinoma.

We report four previously undescribed families with germline BRCA1-associated protein-1 gene (BAP1) mutations and expand the clinical phenotype of this tumor syndrome. The tumor spectrum in these families is predominantly uveal malignant melanoma (UMM), cutaneous malignant melanoma (CMM) and mesothelioma, as previously reported for germline BAP1 mutations. However, mutation carriers from three new families, and one previously reported family, developed basal cell carcinoma (BCC), thus suggesting inclusion of BCC in the phenotypic spectrum of the BAP1 tumor syndrome. This notion is supported by the finding of loss of BAP1 protein expression by immunochemistry in two BCCs from individuals with germline BAP1 mutations and no loss of BAP1 staining in 53 of sporadic BCCs consistent with somatic mutations and loss of heterozygosity of the gene in the BCCs occurring in mutation carriers. Lastly, we identify the first reported recurrent mutation in BAP1 (p.R60X), which occurred in three families from two different continents. In two of the families, the mutation was inherited from a common founder but it arose independently in the third family.

Association of MC1R variants and host phenotypes with melanoma risk in CDKN2A mutation carriers: a GenoMEL study.

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]; P(trend) = 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). CONCLUSION: 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.

Prophylactic but not therapeutic activity of a monoclonal antibody that neutralizes the binding of VEGF-B to VEGFR-1 in a murine collagen-induced arthritis model.

OBJECTIVE: To assess the therapeutic potential of a mAb that neutralizes the binding of VEGF-B to VEGFR-1, to inhibit the pathogenesis of CIA in mice. METHODS: CIA was induced in C57BL6/J and DBA-1 mice by intradermal injection of chick collagen type II (CII) in adjuvant. A neutralizing VEGF-B mAb or an isotype control mAb was then administered by intraperitoneal injection twice weekly beginning either post CII booster injection but prior to or immediately following clinical disease diagnosis. RESULTS: Neutralizing VEGF-B mAb inhibited the development of CIA in C57BL6/J mice in a dose-dependent manner when administered following the CII booster injection, but prior to clinical disease diagnosis. This result was also confirmed in DBA-1 strain mice. In contrast, the neutralizing VEGF-B mAb had no measurable effect on disease severity or progression when treatment commenced from the day of clinical disease diagnosis. CONCLUSIONS: Treatment with an mAb that neutralizes the binding of VEGF-B to VEGFR-1 exhibits prophylactic but not therapeutic actions in a mouse model of RA. These data indicate that while VEGF-B/VEGFR-1 signalling is involved in the early development of arthritis it may not be required for maintenance or progression of established disease.

Leptin and the risk of Barrett's oesophagus.

BACKGROUND: Obesity is associated with increased risks of Barrett's oesophagus and oesophageal adenocarcinoma. Alterations in serum leptin and adiponectin, obesity-related cytokines, have been linked with several cancers and have been postulated as potential mediators of obesity-related carcinogenesis; however, the relationship with Barrett's oesophagus remains unexplored. METHODS: Serum leptin and adiponectin concentrations were measured on two subsets of participants within a case-control study conducted in Brisbane, Australia. Cases were people aged 18-79 years with histologically confirmed Barrett's oesophagus newly diagnosed between 2003 and 2006. Population controls, frequency matched by age and sex to cases, were randomly selected from the electoral roll. Phenotype and medical history data were collected through structured, self-completed questionnaires. Odds ratios (OR) and 95% CI were calculated using multivariable logistic regression analysis. RESULTS: In the pilot analysis (51 cases, 67 controls) risks of Barrett's oesophagus were highest among those in the highest quartile of serum leptin (OR 4.6, 95% CI 0.6 to 33.4). No association was seen with adiponectin. In the leptin validation study (306 cases, 309 controls), there was a significant threefold increased risk of Barrett's oesophagus among men in the highest quartile of serum leptin (OR 3.3, 95% CI 1.7 to 6.6) and this persisted after further adjustment for symptoms of gastro-oesophageal reflux (OR 2.4, 95% CI 1.1 to 5.2). In contrast, the risk of Barrett's oesophagus among women decreased with increasing serum leptin concentrations. CONCLUSIONS: High serum leptin is associated with an increased risk of Barrett's oesophagus among men but not women. This association is not explained simply by higher body mass or gastro-oesophageal reflux among cases. The mechanism remains to be determined.

Gene expression of lung squamous cell carcinoma reflects mode of lymph node involvement.

Tumour, node, metastasis staging is essential for lung cancer management. However, similarly staged cancers may have markedly different prognoses, indicating that stage cannot completely explain tumour behaviour. While ipsilateral hilar node involvement is designated N1, the current authors hypothesised that primary tumours involving nodes by direct extension are biologically distinct from those involving nodes through lymphatic metastasis. Microarrays were used to investigate the gene expression profiles of 59 primary lung squamous cell carcinomas, comparing N0 tumours (n = 35), N1 tumours by direct extension (N1d; n = 8), and N1/N2 tumours by lymphatic metastasis (N1/N2m; n = 16). Hierarchical clustering using 125 genes differentially expressed between N0 and N1/N2m tumours found N1d tumours clustered with N0 tumours. Class prediction modelling found the expression profiles of all eight N1d tumours were more similar to N0 than to N1/N2m tumours. The present study demonstrates for the first time that N1 tumours directly invading hilar nodes are genomically different to those that metastasise via lymphatics. Independent reports suggest that tumours with direct, rather than metastatic node involvement have better outcomes. Consequently, the data suggest that there is a need to re-evaluate the N1 staging definition in lung cancer. This is relevant for prognosis prediction and also for clinical management, particularly in selecting those patients most likely to benefit from adjuvant chemotherapy.

Lack of augmentation of tumor spectrum or severity in dual heterozygous Men1 and Rb1 knockout mice.

To identify possible genetic interactions between the mechanisms of tumor suppression of menin and pRb, we intercrossed mice with targeted deletions of Men1 and Rb1, and compared tumor development in cohorts of animals carrying single or dual mutations of these tumor-suppressor genes. In mice lacking one copy of Men1, pancreatic islet and anterior pituitary adenomas are common. In animals lacking one copy of Rb1, intermediate pituitary and thyroid tumors occur at high frequency, with less frequent development of pancreatic islet hyperplasia and parathyroid lesions. In mice heterozygous for both Men1 and Rb1, pancreatic hyperplasia and tumors of the intermediate pituitary and thyroid occurred at high frequency. Serum measurements of calcium and glucose did not vary significantly between genotypic groups. Loss of heterozygosity at the Rb1 locus was common in pituitary and thyroid tumors, whereas loss of menin was observed in pancreatic and parathyroid lesions. The tumor spectrum in the double heterozygotes was a combination of pathologies seen in each of the individual heterozygotes, without decrease in age of onset, indicating independent, non-additive effects of the two mutations. Together with the lack of increased tumor spectrum, this suggests that menin and pRb function in a common pathway of tumor suppression.

Activation of the MAPK pathway is a common event in uveal melanomas although it rarely occurs through mutation of BRAF or RAS.

In contrast to cutaneous melanoma, there is no evidence that BRAF mutations are involved in the activation of the mitogen-activated protein kinase (MAPK) pathway in uveal melanoma, although there is increasing evidence that this pathway is activated frequently in the latter tumours. In this study, we performed mutation analysis of the RAS and BRAF genes in a panel of 11 uveal melanoma cell lines and 19 primary uveal melanoma tumours. In addition, Western blot and immunohistochemical analyses were performed on downstream members of the MAPK pathway in order to assess the contribution of each of these components. No mutations were found in any of the three RAS gene family members and only one cell line carried a BRAF mutation (V599E). Despite this, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), ERK and ELK were constitutively activated in all samples. These data suggest that activation of the MAPK pathway is commonly involved in the development of uveal melanoma, but occurs through a mechanism different to that of cutaneous melanoma.

Separate and interacting effects within the catechol-O-methyltransferase (COMT) are associated with schizophrenia.

Several lines of evidence have implicated the catechol-O-methyltransferase (COMT) gene as a candidate for schizophrenia (SZ) susceptibility, not only because it encodes a key dopamine catabolic enzyme but also because it maps to the velocardiofacial syndrome region of chromosome 22q11 which has long been associated with SZ predisposition. The interest in COMT as a candidate SZ risk factor has led to numerous case-control and family-based studies, with the majority placing emphasis on examining a functional Val/Met polymorphism within this enzyme. Unfortunately, these studies have continually produced conflicting results. To assess the genetic contribution of other COMT variants to SZ susceptibility, we investigated three single-nucleotide polymorphisms (SNPs) (rs737865, rs4633, rs165599) in addition to the Val/Met variant (rs4680) in a highly selected sample of Australian Caucasian families containing 107 patients with SZ. The Val/Met and rs4633 variants showed nominally significant associations with SZ (P<0.05), although neither of the individual SNPs remained significant after adjusting for multiple testing (most significant P=0.1174). However, haplotype analyses showed strong evidence of an association; the most significant being the three-marker haplotype rs737865-rs4680-rs165599 (global P=0.0022), which spans more than 26 kb. Importantly, conditional analyses indicated the presence of two separate and interacting effects within this haplotype, irrespective of gender. In addition, our results indicate the Val/Met polymorphism is not disease-causing and is simply in strong linkage disequilibrium with a causative effect, which interacts with another as yet unidentified variant approximately 20 kb away. These results may help explain the inconsistent results reported on the Val/Met polymorphism and have important implications for future investigations into the role of COMT in SZ susceptibility.

Ocular melanoma is not associated with CDKN2A or MC1R variants--a population-based study.

Germline variants in the melanocortin 1 receptor gene (MC1R) and the p16 gene (CDKN2A) are associated with an increased risk of cutaneous melanoma. The frequency of these germline variants was examined in a population-based, incident series of 62 ocular melanoma cases and ethnicity-matched population controls. In both cases and controls, 59% of individuals carried at least one MC1R variant and there were no significant differences in the frequency of any of the five most common variants of MC1R. We also found no significant differences between cases and controls in the frequency of any of the four most common variants of CDKN2A, and no melanoma case carried a deleterious germline CDKN2A mutation. Our findings argue against an important predisposing effect of the MC1R and CDKN2A genes for ocular melanoma.

Loss of p16 expression is associated with histological features of melanoma invasion.

While mutations of CDKN2A are associated with melanoma predisposition, the precise role of its gene product p16 in the development of sporadic melanoma is less clearly understood. We sought to determine the prevalence of p16 expression using immunohistochemical analysis in a population-based sample of melanoma tumours, and also to identify histological, phenotypic and environmental factors associated with the presence or absence of p16 expression. We conducted face-to-face interviews with 108 patients newly diagnosed with melanoma to ascertain their history of sun exposure, and recorded various phenotypic parameters. Paraffin sections of tumours from these patients were stained with an anti-p16 monoclonal antibody following antigen retrieval. Overall, 52 (48%) tumours expressed p16; nodular melanomas had significantly lower levels of p16 immunoreactivity than superficial spreading melanomas (P = 0.015). While no association was found between p16 expression and host phenotype, loss of p16 staining was associated with thicker lesions (p = 0.084) and a high mitotic index (P = 0.013). Taken together, these findings are consistent with loss of p16 being a late event in the progression of sporadic primary melanomas, being associated with tumours of a more aggressive nature.

PTEN inactivation is rare in melanoma tumours but occurs frequently in melanoma cell lines.

Deletions detected in cytogenetic and loss of heterozygosity (LOH) studies indicate that at least one tumour suppressor gene maps to the long arm of chromosome 10. Previous deletion mapping studies have observed LOH on 10q in about 30% of melanomas analysed. The PTEN gene, mapping to chromosome band 10q23.3, encodes a protein with both lipid and protein phosphatase activity. Somatic mutations and deletions in have been detected in a variety of cell lines and tumours, including melanoma samples. We performed mutation analyses and extensive allelic loss studies to investigate the role this gene plays in melanoma pathogenesis. We found that a total of 34 out of 57 (60%) melanoma cell lines carried hemizygous deletions of chromosome 10q encompassing the PTEN locus. A further three cell lines carried smaller deletions excluding PTEN. Inactivation of both PTEN alleles by exon-specific homozygous deletion or mutation was observed in 13 out of 57 (23%) melanoma cell lines. The mutation spectrum observed does not indicate an important role for ultraviolet radiation in the genesis of these mutations, and evidence from three cell lines supports the acquisition of PTEN aberrations in culture. Ten out of 49 (20%) matched melanoma tumour/normal samples harboured hemizygous deletions of either the whole chromosome or most of the long arm. Mutations within were detected in only one of the 10 tumours demonstrating LOH at 10q23 that were analysed. These results suggest that PTEN inactivation may be important for the propagation of melanoma cells in culture, and that another chromosome 10 tumour suppressor gene may be important for melanoma pathogenesis.

MC1R genotype modifies risk of melanoma in families segregating CDKN2A mutations.

Mutations in the exons of the cyclin-dependent kinase inhibitor gene CDKN2A are melanoma-predisposition alleles which have high penetrance, although they have low population frequencies. In contrast, variants of the melanocortin-1 receptor gene, MC1R, confer much lower melanoma risk but are common in European populations. Fifteen Australian CDKN2A mutation-carrying melanoma pedigrees were assessed for MC1R genotype, to test for possible modifier effects on melanoma risk. A CDKN2A mutation in the presence of a homozygous consensus MC1R genotype had a raw penetrance of 50%, with a mean age at onset of 58.1 years. When an MC1R variant allele was also present, the raw penetrance of the CDKN2A mutation increased to 84%, with a mean age at onset of 37.8 years (P=.01). The presence of a CDKN2A mutation gave a hazard ratio of 13.35, and the hazard ratio of 3.72 for MC1R variant alleles was also significant. The impact of MC1R variants on risk of melanoma was mediated largely through the action of three common alleles, Arg151Cys, Arg160Trp, and Asp294His, that have previously been associated with red hair, fair skin, and skin sensitivity to ultraviolet light.

CDKN2A is not the principal target of deletions on the short arm of chromosome 9 in neuroendocrine (Merkel cell) carcinoma of the skin.

The majority of small-cell lung cancers (SCLCs) express p16 but not pRb. Given our previous study showing loss of pRb in Merkel cell carcinoma (MCC)/neuroendocrine carcinoma of the skin and the clinicopathological similarities between SCLC and MCC, we wished to determine if this was also the case in MCC. Twenty-nine MCC specimens from 23 patients were examined for deletions at 10 loci on 9p and 1 on 9q. No loss of heterozygosity (LOH) was seen in 9 patients including 2 for which tumour and cell line DNAs were examined. Four patients had LOH for all informative loci on 9p. Ten tumours showed more limited regions of loss on 9p, and from these 2 common regions of deletion were determined. Half of all informative cases had LOH at D9S168, the most telomeric marker examined, and 3 specimens showed loss of only D9S168. A second region (IFNA-D9S126) showed LOH in 10 (44%) cases, and case MCC26 showed LOH for only D9S126, implicating genes centromeric of the CDKN2A locus. No mutations in the coding regions of p16 were seen in 7 cell lines tested, and reactivity to anti-p16 antibody was seen in all 11 tumour specimens examined and in 6 of 7 cell lines from 6 patients. Furthermore, all cell lines examined reacted with anti-p14(ARF) antibody. These results suggest that neither transcript of the CDKN2A locus is the target of deletions on 9p in MCC and imply the existence of tumour-suppressor genes mapping both centromeric and telomeric of this locus.

Mutation analysis of the CDKN2A promoter in Australian melanoma families.

Approximately 50% of all melanoma families worldwide show linkage to 9p21-22, but only about half of these have been shown to contain germ line CDKN2A mutations. It has been hypothesized that a proportion of these families carry mutations in the noncoding regions of CDKN2A. Several Canadian families have been reported to carry a mutation in the 5' UTR, at position -34 relative to the start site, which gives rise to a novel AUG translation initiation codon that markedly decreases translation from the wild-type AUG (Liu et al., 1999). Haplotype sharing in these Canadian families suggested that this mutation is of British origin. We sequenced 1,327 base pairs (bp) of CDKN2A, making up 1,116 bp of the 5' UTR and promoter, all of exon 1, and 61 bp of intron 1, in at least one melanoma case from 110 Australian families with three or more affected members known not to carry mutations within the p16 coding region. In addition, 431 bp upstream of the start codon was sequenced in an additional 253 affected probands from two-case melanoma families for which the CDKN2A mutation status was unknown. Several known polymorphisms at positions -33, -191, -493, and -735 were detected, in addition to four novel variants at positions 120, -252, -347, and -981 relative to the start codon. One of the probands from a two-case family was found to have the previously reported Q50R mutation. No family member was found to carry the mutation at position -34 or any other disease-associated mutation. For further investigation of noncoding CDKN2A mutations that may affect transcription, allele-specific expression analysis was carried out in 31 of the families with at least three affected members who showed either complete or "indeterminate" 9p haplotype sharing without CDKN2A exonic mutations. Reverse transcription polymerase chain reaction and automated sequencing showed expression of both CDKN2A alleles in all family members tested. The lack of CDKN2A promoter mutations and the absence of transcriptional silencing in the germ line of this cohort of families suggest that mutations in the promoter and 5' UTR play a very limited role in melanoma predisposition.

The impact of the Human Genome Project on medical genetics.

The near completion of the Human Genome Project stands as a remarkable achievement, with enormous implications for both science and society. For scientists, it is the first step in a complex process that will lead to important advances in the diagnosis and treatment of many diseases. Society, meanwhile, must prevent genetic discrimination, and protect genetic privacy through appropriate legislation.