Protective effect of copy number polymorphism of glutathione S-transferase T1 gene on melanoma risk in presence of CDKN2A mutations, MC1R variants and host-related phenotypes.

The effect of CDKN2A, the major high-risk melanoma susceptibility gene, has been shown to be modified by host-related phenotypes and variants of MC1R gene. The glutathione S-transferase (GSTs) genes, implicated in detoxification of metabolites after UV exposure, are candidates for modulating CDKN2A penetrance. Few case-control studies have investigated the effect of GSTs on melanoma risk, and have led to controversial results while these genes have not yet been studied in CDKN2A melanoma-prone families. We examined the effect of GSTP1, GSTM1 and GSTT1 genotypes on melanoma risk in 25 multi-generational melanoma-prone families with CDKN2A mutations, in presence of MC1R gene variants, sun exposure, and host-related phenotypes. These data included 195 genotyped subjects for all studied genes. We applied the GEE (Generalized Estimating Equations) approach to test for the effect of GSTs while adjusting for age, sex and CDKN2A mutation status and including successively MC1R, sun exposure and host factors in the model. No significant effect of null GSTM1 allele and GSTP1 variants (p.I105V, p.A114V) on melanoma risk was found. However, a significant protective effect of carrying >or=1 null GSTT1 allele was shown: OR(adjusted for age,sex,CDKN2A ) = 0.41 (0.18-0.94) and OR(adjusted for age,sex,CDKN2A,MC1R ) = 0.24 (0.15-0.58). Altogether, the factors modifying significantly the melanoma risk associated with CDKN2A mutations (stepwise procedure) were: MC1R and dysplastic nevi (increasing the risk) and GSTT1 (decreasing the risk). This study shows that even when a high-risk gene (CDKN2A) has been identified, multiple genetic modifiers influence melanoma risk.

The contribution of large genomic deletions at the CDKN2A locus to the burden of familial melanoma.

Mutations in two genes encoding cell cycle regulatory proteins have been shown to cause familial cutaneous malignant melanoma (CMM). About 20% of melanoma-prone families bear a point mutation in the CDKN2A locus at 9p21, which encodes two unrelated proteins, p16(INK4a) and p14(ARF). Rare mutations in CDK4 have also been linked to the disease. Although the CDKN2A gene has been shown to be the major melanoma predisposing gene, there remains a significant proportion of melanoma kindreds linked to 9p21 in which germline mutations of CDKN2A have not been identified through direct exon sequencing. The purpose of this study was to assess the contribution of large rearrangements in CDKN2A to the disease in melanoma-prone families using multiplex ligation-dependent probe amplification. We examined 214 patients from independent pedigrees with at least two CMM cases. All had been tested for CDKN2A and CDK4 point mutation, and 47 were found positive. Among the remaining 167 negative patients, one carried a novel genomic deletion of CDKN2A exon 2. Overall, genomic deletions represented 2.1% of total mutations in this series (1 of 48), confirming that they explain a very small proportion of CMM susceptibility. In addition, we excluded a new gene on 9p21, KLHL9, as being a major CMM gene.

Molecular basis of the Li-Fraumeni syndrome: an update from the French LFS families.

We have performed an extensive analysis of TP53 in 474 French families suggestive of Li-Fraumeni syndrome (LFS), including 232 families fulfilling the Chompret criteria. We identified a germline alteration of TP53 in 82 families (17%), in 67/232 of the families fulfilling the Chompret criteria (29%) and in 15/242 which did not fulfil these criteria (6%). Most of the alterations corresponded to missense mutations (67%), and we identified in four families genomic deletions removing the entire TP53 locus, the promoter and the non-coding exon 1, or exons 2-10. These results represent a definitive argument demonstrating that LFS results from TP53 haplodeficiency. The mean ages of tumour onset were significantly different between patients harbouring TP53 missense mutations and other types of alterations, missense mutations being associated with a 9 year earlier tumour onset. These results confirm that missense mutations not only inactivate p53 but also have an additional oncogenic effect. Germline alterations of TP53 that lead exclusively to loss of function are therefore associated with a later age of tumour onset and the presence of such mutations should be considered in atypical LFS families with tumours diagnosed after 40 years.

[Prophylactic mastectomies and immediate breast reconstruction in patients at very high genetic risk: our experience with 14 cases]. / Mastectomies prophylactiques et reconstruction immédiate chez les patientes à très haut risque génétique : notre expérience à propos de 14 cas.

AIMS: Prophylactic mastectomy has been the subject of major publications by international groups. Its oncology benefit is undisputed in patients with a genetic mutation. Nevertheless, its impact on quality of life, its psychological, esthetic, sexual, functional and pain repercussions are such that it should not and must never be programmed in an emergency situation. We report our experience with 14 patients at very high genetic risk having undergone a bilateral prophylactic mastectomy with immediate breast reconstructive surgery. METHODS: From 1 March 2001 to 31 March 2006, 14 patients at very high genetic risk, seven of whom had a history of breast cancer, underwent immediate breast reconstruction with skin sparing mastectomy and preservation of the nipple-areolar complex. RESULTS: In 71.5% of the cases, we obtained a definitive conservation of the nipple-areolar complex, with esthetic results judged very satisfying. CONCLUSION: Immediate bilateral breast reconstruction by provisional or definitive implant with conservation of the skin flap and the nipple-areolar complex may constitute a positive radical issue for requesting and motivated patients at high genetic risk, managed by a multidisciplinary team.

The contribution of germline rearrangements to the spectrum of BRCA2 mutations.

BACKGROUND: Few germline BRCA2 rearrangements have been described compared with the large number of germline rearrangements reported in the BRCA1 gene. However, some BRCA2 rearrangements have been reported in families that included at least one case of male breast cancer. OBJECTIVE: To estimate the contribution of large genomic rearrangements to the spectrum of BRCA2 defects. METHODS: Quantitative multiplex PCR of short fluorescent fragments (QMPSF) was used to screen the BRCA2 gene for germline rearrangements in highly selected families. QMPSF was previously used to detect heterozygous deletions/duplications in many genes including BRCA1 and BRCA2. RESULTS: We selected a subgroup of 194 high risk families with four or more breast cancers with an average age at diagnosis of < or = 50 years, who were recruited through 14 genetic counselling centres in France and one centre in Switzerland. BRCA2 mutations were detected in 18.6% (36 index cases) and BRCA1 mutations in 12.4% (24 index cases) of these families. Of the 134 BRCA1/2 negative index cases in this subgroup, 120 were screened for large rearrangements of BRCA2 using QMPSF. Novel and distinct BRCA2 deletions were detected in three families and their boundaries were determined. We found that genomic rearrangements represent 7.7% (95% confidence interval 0% to 16%) of the BRCA2 mutation spectrum. CONCLUSION: The molecular diagnosis of breast cancer predisposition should include screening for BRCA2 rearrangements, at least in families with a high probability of BRCA2 defects.

An ovarian dysgerminoma in Down syndrome. Hypothesis about the association.

An 11-year-old girl with Down syndrome (DS) was operated for a stage I right ovary dysgerminoma. She is in good health 33 years later. Some data in the literature suggest that ovarian cancers could be slightly overrepresented in DS. Despite the rarity of ovarian dysgerminoma, our case is the fifth reported in DS. This case is the second one associated with a family history suggesting the possibility of a familial predisposition to cancer. A hypothesis explaining the development of dysgerminoma in DS is proposed.

[Clinical and genetic study in 22 patients with basal cell nevus syndrome]. / Etude clinique et recherche de mutations germinales du gène PTCH 1 dans le syndrome des hamartomes basocellulaires.

BACKGROUND: Nevoid basal cell carcinoma syndrome is an autosomal dominant disorder characterized by developmental abnormalities and cancer predisposition. The PTCH 1 gene, the human homolog of the Drosophila segment polarity gene patched, has been shown to be involved in the development of nevoid basal cell carcinoma syndrome. PTCH 1 is mapped to chromosome 9q22.3. The aim of the present study was to report on clinical and genetic characteristics in patients followed for nevoid basal cell carcinoma syndrome and to compare them to the data in the literature. PATIENTS AND METHODS: Screening for PTCH 1 mutations was done in 22 patients followed between 1981 and 2003 for clinical suspicion of nevoid basal cell carcinoma syndrome. Clinical and radiological data were reviewed retrospectively from records. Genetic analysis was performed using blood samples after patient informed consent was obtained. When possible, DNA was also analyzed from the parents of patients in whom PTCH 1 mutations were found. RESULTS: All patients had developed basal cell carcinomas: 45% palmar and plantar pitting, 62% jaw cysts and 66% calcification of falx cerebri. Medulloblastomas and meningiomas were the most common associated tumors. PTCH 1 mutations were identified in 13 patients: 6 familial cases, 3 sporadic cases and for 4 patients, it was not possible to conclude. Nine different new germ-line mutations were identified. DISCUSSION: Genetic analysis allows molecular confirmation of diagnosis in about half of all patients. Early diagnosis is essential for detection of clinical and radiological manifestations in young patients and for provision of advice concerning protection of the skin from the sunlight.

Comprehensive analysis of CDKN2A (p16INK4A/p14ARF) and CDKN2B genes in 53 melanoma index cases considered to be at heightened risk of melanoma.

OBJECTIVE: Comprehensive analysis of the 9p21 locus including the CDKN2A, ARF, and CDKN2B genes in 53 individuals from melanoma index cases considered to be at heightened risk of melanoma. METHODS AND RESULTS: Using a combination of DNA sequencing, gene copy number by real time quantitative PCR, linkage analysis, and transcript analysis in haploid somatic cell hybrids, we found no evidence for germline alteration in either coding or non-coding domains of CDKN2A and CDKN2B. However, we identified a p14ARF exon 1beta missense germline mutation (G16D) in a melanoma-neural system tumour syndrome (CMM+NST) family and a 8474 bp germline deletion from 196 bp upstream of p14ARF exon 1beta initiation codon to 11233 bp upstream of exon 1alpha of p16(INK4A) in a family with five melanoma cases. For three out of 10 families with at least three melanoma cases, the disease gene was unlinked to the 9p21 region, while linkage analysis was not fully conclusive for seven families. CONCLUSIONS: These data reinforce the hypothesis that ARF is a melanoma susceptibility gene and suggest that germline deletions specifically affecting p14ARF may not be solely responsible for NST susceptibility. Predisposition to CMM+NST could either be due to complete disruption of the CDKN2A locus or be the result of more complex genetic inheritance. In addition, the absence of any genetic alteration in 50 melanoma prone families or patients suggests the presence of additional tumour suppressor genes possibly in the 9p21 region, and on other chromosomes.

Impact of the MDM2 SNP309 and p53 Arg72Pro polymorphism on age of tumour onset in Li-Fraumeni syndrome.

Li-Fraumeni syndrome, resulting from p53 (TP53) germline mutations, represents one of the most devastating genetic predispositions to cancer. Recently, the MDM2 SNP309 (T-->G variation) was shown to be associated with accelerated tumour formation in p53 mutation carriers. The impact of the common p53 codon 72 polymorphism on cancer risk remains controversial. We therefore investigated the effect of these two polymorphisms in 61 French carriers of the p53 germline mutation. The mean age of tumour onset in MDMD2 SNP309 G allele carriers (19.6 years) was significantly different from that observed in patients homozygous for the T allele (29.9 years, p<0.05). For the p53 codon 72 polymorphism, the mean age of tumour onset in Arg allele carriers (21.8 years) was also different from that of Pro/Pro patients (34.4 years, p<0.05). We observed a cumulative effect of both polymorphisms because the mean ages of tumour onset in carriers of the MDM2G and p53Arg alleles (16.9 years) and those with the MDM2T/T and p53Pro/Pro genotypes (43 years) were clearly different (p<0.02). Therefore, our results confirm the impact of the MDM2 SNP309 G allele on the age of tumour onset in germline p53 mutation carriers, and suggest that this effect may be amplified by the p53 72Arg allele. Polymorphisms affecting p53 degradation therefore represent one of the rare examples of modifier genetic factors identified to date in mendelian predispositions to cancer.

Surgical procedure in patients with ovarian cancer diagnosed at the time of prophylactic oophorectomy. Analysis of two cases, literature review and surgical implications.

The aim of this study was to discuss the surgical management for ovarian or tubal cancers diagnosed at the time of prophylactic oophorectomy. Two patients with BRCA1 & BRCA2 mutations carriers had ovarian cancer diagnosed during laparoscopic oophorectomy. Conversion to laparotomy was performed in order to complete surgery (hysterectomy, multiple peritoneal biopsies, omentectomy, pelvic and para-aortic lymphadenectomy). These two patients were upstaged on the basis of para-aortic lymphadenectomy and had massive nodal spread into para-aortic area. One of them had no intra-peritoneal disease and the other one had minor peritoneal disease (only one positive pelvic biopsy in the Douglas pouch). These two patients are alive, one of them with 3.5 years of follow-up after the end of adjuvant treatment. In order to ensure the exact spread of the disease. Lymphadenectomy should be performed in patients with ovarian cancer diagnosed at the time of prophylactic surgery.

[Clinical and molecular diagnosis of inherited breast-ovarian cancer]. / Diagnostic génétique du cancer du sein et de l'ovaire héréditaire.

OBJECTIVE: The aim of this work was to pinpoint familial breast and/or ovarian cancer risk. Clinical cancer genetics include: diagnostic cancer genetics, cancer genetic counseling and management of women at high risk of developing breast and/or ovarian cancer. MATERIAL AND METHODS: An update of documented data was performed in order to assess our current knowledge about inherited breast-ovarian cancer. RESULTS: Most breast cancers (BC) are sporadic while 5-10% are estimated to be due to an inherited predisposition. Rare autosomal dominant alteration in two genes, BRCA1 and BRCA2, which confer a high risk of developing BC and ovarian cancer (OC), are likely to account for most families with multiple cases of early-onset BC and OC, but only 3-4% of all BC. The estimations of their prevalence and penetrance vary greatly, depending on the population studied, the study design, statistical methods and the sensitivity of technical methods for detection of mutations. Penetrance can be very high, but incomplete (maximum 80%). Penetrance and age at onset of the same mutation show great variability within and between BC families. This could be due to the effects of other genetic as well as non-genetic factors that are being studied. The heterogeneity of families makes the identification of other high-risk genes difficult. Additive effects of several susceptibility genes could explain much more BC in the general population (polygenic models). Molecular diagnoses have become feasible. Specific consultations in oncogenetics help clinicians and patients understand hereditary components, establish molecular diagnoses, provide guidelines for a better surveillance of people at high risk of developing BC, OC or both and reassure the mutation non-carriers. The strategies of management and treatment of BC and OC in mutation carriers remain under discussion and it is is difficult to choose preventive options. CONCLUSION: Inherited BC or OC due to a mutation in BRCA1 or BRCA2 are rare in the general population. However, women and men have the right to be informed of the possibilities concerning presymptomatic testing, risk assessment, surveillance, prevention and psychological support with respect to the potential benefits and limitations. Other large prospective studies are needed to validate rapidly the methods of surveillance and prevention in this group at "high risk" in order to adapt them to very large populations. However, predictive medicine should be used with care.

Sporadic multiple primary melanoma cases: CDKN2A germline mutations with a founder effect.

Multiple primary cancers are one of the hallmarks of inherited predisposition. Outside the familial context, multiple primary tumors could be related either to germline de novo mutations or to low-penetrance mutations, in predisposing genes. We selected 100 patients who displayed multiple primary melanoma (MPM) without any known melanoma cases recorded within their families and looked for germline mutations in the two melanoma-predisposing genes identified to date, CDKN2A and CDK4 exon 2. Nine patients (9%) had germline mutations in CDKN2A, whereas none carried germline mutations in exon 2 of CDK4. Seven cases displayed a recurrent missense mutation, G101W, already described in more than 20 melanoma-prone families; one case carried a missense mutation never reported to date (P114S), and the last case was a carrier of a 6 bp insertion at nucleotide 57 resulting in a duplication of codons 18 and 19. To ascertain whether the G101W was a mutational hot spot for de novo mutations or a common founder mutation, we genotyped eight microsatellite markers flanking the CDKN2A gene. After allowing for recombination over time, haplotype sharing provided evidence for an original G101W mutation common to 6 out of 7 sporadic MPM cases. Therefore, it can be concluded that de novo germline CDKN2A mutations associated with MPM are rare.

[Genetic diagnosis of cancers? Which cancers should be screened?]. / Diagnostic génétique des cancers? Pour quels cancers?

Our knowledge in the genetic basis of hereditary human cancer has improved over the last 10 years. Molecular diagnoses have become feasible in major hereditary cancer-prone syndromes, as well as in other hereditary diseases in which cancer appears as symptoms or complications. The major cancer-prone syndromes are described here with a table summarizing the links between various cancer types and the genetic syndromes to which they could belong. Clinicians should be aware of these new diagnostic tools. Specific consultations in oncogenetics are being settled to help clinicians and patients in the course of establishing molecular diagnoses, and providing guidelines for a better surveillance of high-risk persons.

[Li-Fraumeni syndrome: update, new data and guidelines for clinical management]. / Le syndrome de Li-Fraumeni: mise au point, données nouvelles et recommandations pour la prise en charge.

The Li-Fraumeni syndrome (LFS) is an inherited form of cancer, affecting children and young adults, and characterized by a wide spectrum of tumors, including soft-tissue and bone sarcomas, brain tumours, adenocortical tumours and premenopausal breast cancers. In most of the families, LFS results from germline mutations of the tumor suppressor TP53 gene encoding a transcriptional factor able to regulate cell cycle and apoptosis when DNA damage occurs. Recently, germline mutations of hCHK2 encoding a kinase, regulating cell cycle via Cdc25C and TP53, were identified in affected families. The LFS working group recommendations are the following: (i) positive testing (screening for a germline TP53 mutation in a patient with a tumor) can be offered both to children and adults in the context of genetic counseling associated to psychological support, to confirm the diagnosis of LFS on a molecular basis. This will allow to offer to the patient a regular clinical review in order to avoid a delay to the diagnosis of another tumor; (ii) the 3 indications for positive testing are: a proband with a tumor belonging to the narrow LFS spectrum and developed before age 36 and, at least, first- or second-degree relative with a LFS spectrum tumor, before age 46, or a patient with multiple primary tumors, 2 of which belonging to the narrow LFS spectrum, the first being developed before 36 or a child with an adenocortical tumour; (iii) presymptomatic testing must be restricted to adults; (iv) the young age of onset of the LFS tumors the prognosis of some tumors, the impossibility to ensure an efficient early detection and the risk for mutation carriers to develop multiple primary tumors justify that prenatal diagnosis might be considered in affected families.

Genomic and allelic expression status of the p73 gene in human neuroblastoma.

BACKGROUND AND PROCEDURE: The p53 gene homologue, p73, is located on the 1p36-3 locus, which is frequently deleted in human neuroblastoma (NB). A survey of 61 NB showed that among 33% of informative cases, p73 loss of heterozygosity (LOH) occurred in 7 of 20 (35%). RESULTS: LOH pattern of vicinal markers suggested that the p73 gene could not be considered as the candidate NB suppressor gene. Moreover, comparative measurements of allelic expression in tumors and corresponding patient lymphocytes indicate that pure biallelism is much more frequent in lymphocytes than in tumors (71% vs 30%, P= 0.05), which suggests that disequilibrated allelic expression is associated with NB disease. CONCLUSION: Therefore, in the p73 LOH NBs, the p73 gene could be altered in the maintained allele not by mutations [Ishimiya et al.: Med Pediatr Oncol, this issue], but rather by an abnormal transcription.