P53 germline mutations in childhood cancers and cancer risk for carrier individuals

The evolution of cancer risk assessment in the era of next generation sequencing

Cancer genetics professionals face a new opportunity and challenge in adapting to the availability of cancer genetic testing panels, now available as a result of Next Generation Sequencing (NGS) technology. While cancer panels have been available for over a year, we believe that there is not yet enough data to create practice guidelines. Despite this, a year of experience allows us to provide our opinion on points to consider as cancer genetic counselors incorporate this testing technology into genetic counseling practice models. NGS technology offers the ability to potentially diagnose hereditary cancer syndromes more efficiently by testing many genes at once for a fraction of what it would cost to test each gene individually. However, there are limitations and additional risks to consider with these tests. Obtaining informed consent for concurrent testing of multiple genes requires that genetics professionals modify their discussions with patients regarding the potential cancer risks and the associated implications to medical management. We propose dividing the genes on each panel into categories that vary by degree of cancer risk (e.g. penetrance of the syndrome) and availability of management guidelines, with the aim to improve patient understanding of the range of information that can come from this testing. The increased risk for identifying variants of uncertain significance (VUS) when testing many genes at once must be discussed with patients. Pretest genetic counseling must also include the possibility to receive unexpected results as well as the potential to receive a result in the absence of related medical management guidelines. It is also important to consider whether a single gene test remains the best testing option for some patients. As panels expand, it is important that documentation reflects exactly which genes have been analyzed for each patient. While this technology holds the promise of more efficient diagnosis for many of our patients, it also comes with new challenges that we must recognize and address.

Genetics and epigenetics of adrenocortical tumors

Adrenocortical tumors are common neoplasms. Most are benign, nonfunctional and clinically irrelevant. However, adrenocortical carcinoma is a rare disease with a dismal prognosis and no effective treatment apart from surgical resection. The molecular genetics of adrenocortical tumors remain poorly understood. For decades, molecular studies relied on a small number of samples and were directed to candidate-genes. This approach, based on the elucidation of the genetics of rare genetic syndromes in which adrenocortical tumors are a manifestation, has led to the discovery of major dysfunctional molecular pathways in adrenocortical tumors, such as the IGF pathway, the Wnt pathway and TP53. However, with the advent of high-throughput methodologies and the organization of international consortiums to obtain a larger number of samples and high-quality clinical data, this paradigm is rapidly changing. In the last decade, genome-wide expression profile studies, microRNA profiling and methylation profiling allowed the identification of subgroups of tumors with distinct genetic markers, molecular pathways activation patterns and clinical behavior. As a consequence, molecular classification of tumors has proven to be superior to traditional histological and clinical methods in prognosis prediction. In addition, this knowledge has also allowed the proposal of molecular-targeted approaches to provide better treatment options for advanced disease. This review aims to summarize the most relevant data on the rapidly evolving field of genetics of adrenal disorders.

Adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy, often with an unfavorable prognosis. Here we summarize the knowledge about diagnosis, epidemiology, pathophysiology, and therapy of ACC. Over recent years, multidisciplinary clinics have formed and the first international treatment trials have been conducted. This review focuses on evidence gained from recent basic science and clinical research and provides perspectives from the experience of a large multidisciplinary clinic dedicated to the care of patients with ACC.

TP53 p.R337H prevalence in a series of Brazilian hereditary breast cancer families

Background

Approximately 5-10% of breast cancers are hereditary. Among hereditary syndromes, Hereditary Breast and Ovarian Cancer Syndrome (HBOC) and Li-Fraumeni Syndrome (LFS) have received the most attention. HBOC is due to mutations in the BRCA1 and BRCA2 genes and is characterized by breast adenocarcinoma and/or epithelial ovarian carcinoma. LFS is associated with germline mutations in TP53; the most frequent cancer types associated with this syndrome are sarcoma, breast cancer, leukemia, brain tumors and adrenocortical carcinomas. Other cancers related to LFS are found at lower frequencies. In Brazil, especially in the southern part of the country, a specific mutation in the TP53 gene, TP53 p.R337H, occurs at a high frequency in childhood adrenocortical tumors. It has been proposed that this mutation increases breast cancer risk in southern Brazilian women.

Methods

We carried out a case-control study to determine the prevalence of the TP53 p.R337H mutation in 28 female cancer patients attended at the Cancer Genetic Counseling Service of the General Hospital of the University of São Paulo Medical School of Ribeirão Preto who fulfilled Hereditary Breast and Ovary Cancer Syndrome genetic test criteria compared to healthy woman (controls). TP53 p.R337H mutation status was determined using the High Resolution Melting (HRM) method, followed by DNA sequencing. Fisher’s test was used to compare the prevalence of TP53 p.R337H in the patient and control groups.

Results

Two of the breast cancer cases (7.1%) and none of the controls carried the TP53 p.R337H mutation. At the time of the investigation, both cases fulfilled testing criteria for Hereditary Breast and Ovary Cancer Syndrome but not Li-Fraumeni or Li-Fraumeni-like Syndrome, based on genetic testing criteria of NCCN Clinical Practice Guidelines in Oncology (v.1.2010).

Conclusions

We suggest that genetic screening of Brazilian breast cancer patients who fulfill Hereditary Breast and Ovary Cancer Syndrome criteria and have a family history that includes other tumors of the LFS/LFL spectrum be tested for the TP53 p.R337H mutation.

Cancer risk assessment using genetic panel testing: considerations for clinical application

With the completion of the Human Genome Project and the development of high throughput technologies, such as next-generation sequencing, the use of multiplex genetic testing, in which multiple genes are sequenced simultaneously to test for one or more conditions, is growing rapidly. Reflecting underlying heterogeneity where a broad range of genes confer risks for one or more cancers, the development of genetic cancer panels to assess these risks represents just one example of how multiplex testing is being applied clinically. There are a number of issues and challenges to consider when conducting genetic testing for cancer risk assessment, and these issues become exceedingly more complex when moving from the traditional single-gene approach to panel testing. Here, we address the practical considerations for clinical use of panel testing for breast, ovarian, and colon cancers, including the benefits, limitations and challenges, genetic counseling issues, and management guidelines.

Realizing the promise of cancer predisposition genes

Genes in which germline mutations confer highly or moderately increased risks of cancer are called cancer predisposition genes. More than 100 of these genes have been identified, providing important scientific insights in many areas, particularly the mechanisms of cancer causation. Moreover, clinical utilization of cancer predisposition genes has had a substantial impact on diagnosis, optimized management and prevention of cancer. The recent transformative advances in DNA sequencing hold the promise of many more cancer predisposition gene discoveries, and greater and broader clinical applications. However, there is also considerable potential for incorrect inferences and inappropriate clinical applications. Realizing the promise of cancer predisposition genes for science and medicine will thus require careful navigation.

Solid tumor second primary neoplasms: who is at risk, what can we do?

Eighteen percent of incident malignancies in the United States are a second (or subsequent) cancer. Second primary neoplasms (SPNs), particularly solid tumors, are a major cause of mortality and serious morbidity among cancer survivors successfully cured of their first cancer. Multiple etiologies may lead to a cancer survivor subsequently being diagnosed with an SPN, including radiotherapy for the first cancer, unhealthy lifestyle behaviors, genetic factors, aging, or an interaction between any of these factors. In this article, we discuss these factors and synthesize this information for use in clinical practice, including preventive strategies and screening recommendations for SPNs.

Predisposition to pediatric and hematologic cancers: a moving target

Our understanding of hereditary cancer syndromes in children, adolescents, and young adults continues to grow. In addition, we now recognize the wide variation in tumor spectrum found within each specific cancer predisposition syndrome including the risk for hematologic malignancies. An increased understanding of the genetic mutations, biologic consequences, tumor risk, and clinical management of these syndromes will improve patient outcome. In this article, we illustrate the diversity of molecular mechanisms by which these disorders develop in both children and adults with a focus on Li-Fraumeni syndrome, hereditary paraganglioma syndrome, DICER1 syndrome, and multiple endocrine neoplasia syndrome. This is followed by a detailed discussion of adult-onset tumors that can occur in the pediatric population including basal cell carcinoma, colorectal cancer, medullary thyroid cancer, and adrenal cortical carcinoma, and the underlying hereditary cancer syndromes that these tumors could indicate. Finally, the topic of leukemia predisposition syndromes is explored with a specific focus on the different categories of syndromes associated with leukemia risk (genetic instability/DNA repair syndromes, cell cycle/differentiation, bone marrow failure syndromes, telomere maintenance, immunodeficiency syndromes, and transcription factors/pure familial leukemia syndromes). Throughout this article, special attention is made to clinical recognition of these syndromes, genetic testing, and management with early tumor surveillance and screening.

Multiplex genetic cancer testing identifies pathogenic mutations in TP53 and CDH1 in a patient with bilateral breast and endometrial adenocarcinoma

Background

Germline genetic testing for familial cancer syndromes is usually performed serially for the most likely genetic causes. In recent years the way genetic testing carried out has changed, as next generation sequencing now allows the simultaneous testing of multiple susceptibility genes at low costs.

Case presentation

Here, we present a female with bilateral breast cancer and endometrial adenocarcinoma. After simultaneous sequencing of 150 genes (890 kb) associated with hereditary cancer we identified pathogenic mutations in two high-penetrance genes, i.e. TP53 and CDH1 that would most likely not have been elucidated by serial screening of candidate genes.

Conclusion

As the two mutated genes are located on different chromosomes and cause different cancer syndromes these findings had a tremendous impact not only on genetic counseling of the index patient and her family but also on subsequent surveillance strategies.

Hereditary cancer risk assessment: essential tools for a better approach

Hereditary cancer risk assessment (HCRA) is a multidisciplinary process of estimating probabilities of germline mutations in cancer susceptibility genes and assessing empiric risks of cancer, based on personal and family history. It includes genetic counseling, testing and management of at-risk individuals so that they can make well-informed choices about cancer surveillance, surgical treatment and chemopreventive measures, including biomolecular cancer therapies. Providing patients and family members with an appropriate HCRA will contribute to a better process of making decisions about their personal and family risks of cancer. Following individuals at high risk through screening protocols, reassuring those at low risk, and referring those at increased risk of hereditary cancer to a cancer genetics center may be the best suitable approach of HCRA.

Tumor protein p53 (TP53) testing and Li-Fraumeni syndrome : current status of clinical applications and future directions

Prevalent as an acquired abnormality in cancer, the role of tumor protein p53 (TP53) as a germline mutation continues to evolve. The clinical impact of a germline TP53 mutation is often dramatic and affects the full life course, with a propensity to develop rare tumors in childhood and multiple common cancers of unexpectedly early onset in adulthood. In this article, we review the clinical relevance of germline mutations in the TP53 tumor suppressor gene to current healthcare practice, including the optimal ways to identify patients with Li-Fraumeni syndrome (LFS), to recognize the core cancers associated with LFS, and to develop strategies for early detection of LFS-associated tumors. Several TP53-targeted approaches to improve outcomes in LFS patients are also reviewed. A case report is used to highlight special TP53 testing dilemmas and unique challenges associated with genetic testing decisions in the current age of rapidly advancing genomic technologies.

The attitudes of people with sarcoma and their family towards genomics and incidental information arising from genetic research

Purpose

The study aimed to examine attitudes of individuals diagnosed with sarcoma and their family members towards genetics, genomic research and incidental information arising as a result of participating in genetic research.

Methods

A questionnaire was administered to 1200 individuals from the International Sarcoma Kindred Study (ISKS). Respondents were divided into three groups: individuals affected with sarcoma (probands), their spouses and family members.

Results

Approximately half of all research participants felt positively towards new discoveries in human genetics. Overall, more were positive in their attitudes towards genetic testing for inherited conditions (60%) but family members were less so. Older participants reported more highly positive attitudes more often than younger participants. Males were less likely to feel positive about new genetic discoveries and more likely to believe they could modify genetic risk by altering lifestyle factors. Almost all ISKS participants believed participants would like to be given ancillary information arising as a result of participating in genetic research.

Conclusions

The only difference between the study groups was the decreased likelihood of family members being highly positive about genetic testing. This may be important if predictive testing for sarcoma becomes available. Generally ISKS research participants supported the notion of returning incidental genetic information to research participants.

High frequency of germline TP53 mutations in a prospective adult-onset sarcoma cohort

Sarcomas are a key feature of Li-Fraumeni and related syndromes (LFS/LFL), associated with germline TP53 mutations. Current penetrance estimates for TP53 mutations are subject to significant ascertainment bias. The International Sarcoma Kindred Study is a clinic-based, prospective cohort of adult-onset sarcoma cases, without regard to family history. The entire cohort was screened for mutations in TP53 using high-resolution melting analysis and Sanger sequencing, and multiplex-ligation-dependent probe amplification and targeted massively parallel sequencing for copy number changes. Pathogenic TP53 mutations were detected in blood DNA of 20/559 sarcoma probands (3.6%); 17 were germline and 3 appeared to be somatically acquired. Of the germline carriers, one appeared to be mosaic, detectable in the tumor and blood, but not epithelial tissues. Germline mutation carriers were more likely to have multiple cancers (47% vs 15% for non-carriers, P = 3.0×10⁻³), and earlier cancer onset (33 vs 48 years, P = 1.19×10⁻³). The median survival of mutation carriers following first cancer diagnosis was not significantly different from non-carriers. Only 10/17 (59%) pedigrees met classical or Chompret criteria for LFS. In summary, germline TP53 mutations are not rare in adult patients with sarcoma, with implications for screening, surveillance, treatment and genetic counselling of carriers and family members.

10 rare tumors that warrant a genetics referral

The number of described cancer susceptibility syndromes continues to grow, as does our knowledge on how to manage these syndromes with the aim of early detection and cancer prevention. Oncologists now have greater responsibility to recognize patterns of cancer that warrant referral for a genetics consultation. While some patterns of common cancers are easy to recognize as related to hereditary cancer syndromes, there are a number of rare tumors that are highly associated with cancer syndromes yet are often overlooked given their infrequency. We present a review of ten rare tumors that are strongly associated with hereditary cancer predisposition syndromes: adrenocortical carcinoma, carcinoid tumors, diffuse gastric cancer, fallopian tube/primary peritoneal cancer, leiomyosarcoma, medullary thyroid cancer, paraganglioma/pheochromocytoma, renal cell carcinoma of chromophobe, hybrid oncocytoic, or oncocytoma histology, sebaceous carcinoma, and sex cord tumors with annular tubules. This review will serve as a guide for oncologists to assist in the recognition of rare tumors that warrant referral for a genetic consultation.

A case of late-onset Li-Fraumeni-like syndrome with unilateral breast cancer

Li-Fraumeni syndrome (LFS) is a rare, inherited syndrome associated with increased risk of various early-onset tumors. Since the introduction of classic LFS criteria, various criteria have been proposed to include patients with incomplete LFS features, which make up Li-Fraumeni-like syndromes (LFL). Germline missense mutations of TP53 are the primary cause of LFS and LFL. Mutations mostly reside in the DNA-binding domain of the gene and have a dominant-negative effect (DNE) over alternate wild-type alleles. Germline TP53 mutation c.566C>T results in the missense mutation GCC (Ala) to GTC (Val) at codon 189 (A189V) and has been reported in a case of multiple primary colon tumors. Herein we report a second case of the same mutation in a breast cancer patient, who has familial history of late-onset malignancies. Due to the relatively late onset of malignancies, neither case fulfils previously defined criteria for the syndrome. Mutational analysis for breast tissue in this patient showed a loss of heterozygosity. These clinical features may suggest a relatively weak DNE of A189V compared to other TP53 mutations, and in silico predictions and in vitro findings of the function of A189V mutant protein are conflicting. Considering the increased risk of malignancies and the therapeutic implications for patients who have a TP53 mutation, care must be taken when treating those who are suspected of possessing cancer-prone traits due to TP53 mutation, especially when there is a family history of late-onset cancer with low penetrance.

Li Fraumeni syndrome, cancer and senescence: a new hypothesis

Li Fraumeni Syndrome (LFS) is a rare autosomal dominant hereditary cancer syndrome characterized by germline mutations in the TP53 tumour suppressor gene. Sufferers are prone to early onset cancers, particularly sarcomas, adrenocortical carcinoma and breast cancer. Cells from LFS sufferers are known to exhibit telomere dysfunction, genomic instability and spontaneous immortalisation. It is hypothesized that these facets of the LFS host are evidence that the host environment is "primed" for carcinogenesis over and above the lack of p53 tumour suppressor function. Further, it is hypothesized that the host presents an ideal environment for "two compartment tumour metabolism" to take place. Evidence from recent studies supports this new view of LFS and suggests that disrupting certain features of the host environment may markedly reduce the incidence of cancer in LFS sufferers.

Hereditary breast cancer: the era of new susceptibility genes

Breast cancer is the most common malignancy among females. 5%-10% of breast cancer cases are hereditary and are caused by pathogenic mutations in the considered reference BRCA1 and BRCA2 genes. As sequencing technologies evolve, more susceptible genes have been discovered and BRCA1 and BRCA2 predisposition seems to be only a part of the story. These new findings include rare germline mutations in other high penetrant genes, the most important of which include TP53 mutations in Li-Fraumeni syndrome, STK11 mutations in Peutz-Jeghers syndrome, and PTEN mutations in Cowden syndrome. Furthermore, more frequent, but less penetrant, mutations have been identified in families with breast cancer clustering, in moderate or low penetrant genes, such as CHEK2, ATM, PALB2, and BRIP1. This paper will summarize all current data on new findings in breast cancer susceptibility genes.

siRNA screening identifies differences in the Fanconi anemia pathway in BALB/c-Trp53+/- with susceptibility versus C57BL/6-Trp53+/- mice with resistance to mammary tumors

BALB/c mice heterozygous for Trp53 develop a high proportion of spontaneous mammary tumors, a phenotype distinct from other mouse strains. BALB/c-Trp53+/- female mice, thus, resemble the hereditary Li-Fraumeni syndrome (LFS) characterized by early-onset of breast cancer, even though LFS involves TP53 mutations, which may involve not only loss- but also gain-of-function. Previous analysis of tumors in BALB/c-Trp53+/- females showed frequent loss of heterozygosity involving the wild-type allele of Trp53 and displayed characteristics indicative of mitotic recombination. Critical involvement of DNA double-strand break (DSB) repair dysfunction, particularly of homologous recombination (HR), was also noticed in the etiology of human breast cancer. To better define functional alterations in BALB/c-Trp53+/- mice, we applied a fluorescence-based DSB repair assay on mouse embryonic fibroblasts (MEFs) from BALB/c-Trp53+/- versus C57BL/6J-Trp53+/- mice. This approach revealed deregulation of HR but not non-homologous end-joining (NHEJ) in BALB/c-Trp53+/-, which was further confirmed for mammary epithelial cells. Screening of a small interfering RNA-library targeting DSB repair, recombination, replication and signaling genes, identified 25 genes causing differences between homologous DSB repair in the two strains upon silencing. Interactome analysis of the hits revealed clustering of replication-related and fanconi anemia (FA)/breast cancer susceptibility (BRCA) genes. Further dissection of the functional change in BALB/c-Trp53+/- by immunofluorescence microscopy of nuclear 53BP1, Replication protein A (RPA) and Rad51 foci uncovered differences in crosslink and replication-associated repair. Chromosome breakage, G2 arrest and biochemical analyses indicated a FA pathway defect downstream of FancD2 associated with reduced levels of BRCA2. Consistent with polygenic models for BRCA, mammary carcinogenesis in BALB/c-Trp53+/- mice may, therefore, be promoted by a BRCA modifier allele in the FA pathway in the context of partial p53 loss-of-function.

Somatic mutagenesis in autoimmunity

Our laboratory investigates systemic autoimmune disease in the context of mouse models of systemic lupus erythematosus (SLE). SLE is associated with high titers of serum autoantibodies of the IgG class that are predominantly directed against nuclear antigens, with pathological manifestations that are considered by many to be characteristic of an immune-complex mediated disease. In this review, we focus on the known and potential roles of somatic mutagenesis in SLE. We will argue that anti-nuclear antibodies (ANA) arise predominantly from nonautoreactive B cells that are transformed into autoreactive cells by the process of somatic hypermutation (SHM), which is normally associated with affinity maturation during the germinal center reaction. We will also discuss the role of SHM in creating antigenic peptides in the V region of the B cell receptor (BCR) and its potential to open an avenue of unregulated T cell help to autoreactive B cells. Finally, we will end this review with new experimental evidence suggesting that spontaneous somatic mutagenesis of genes that regulate B cell survival and activation is a rate-limiting causative factor in the development of ANA.

Prevalence of germline TP53 mutations in a prospective series of unselected patients with adrenocortical carcinoma

PURPOSE

Adrenocortical carcinoma (ACC) is a hallmark cancer in families with Li Fraumeni syndrome (LFS) caused by mutations in the TP53 gene. The prevalence of germline TP53 mutations in children diagnosed with ACC ranges from 50-97%. Although existing criteria advocate for TP53 testing in all patients with ACC regardless of age at diagnosis, the overall prevalence of germline mutations in patients diagnosed with ACC has not been well studied.

PATIENTS AND METHODS

A total of 114 patients with confirmed ACC evaluated in the University of Michigan Endocrine Oncology Clinic were prospectively offered genetic counseling and TP53 genetic testing, regardless of age at diagnosis or family history. Ninety-four of the 114 patients met with a genetic counselor (82.5%), with 53 of 94 (56.4%) completing TP53 testing; 9.6% (nine of 94) declined testing. The remainder (32 of 94; 34%) expressed interest in testing but did not pursue it for various reasons.

RESULTS

Four of 53 patients in this prospective, unselected series were found to have a TP53 mutation (7.5%). The prevalence of mutations in those diagnosed over age 18 was 5.8% (three of 52). There were insufficient data to estimate the prevalence in those diagnosed under age 18. None of these patients met clinical diagnostic criteria for classic LFS. Three of the families met criteria for Li Fraumeni-like syndrome; one patient met no existing clinical criteria for LFS or Li Fraumeni-like syndrome. Three of the four patients with mutations were diagnosed with ACC after age 45.

CONCLUSIONS

Genetic counseling and germline testing for TP53 should be offered to all patients with ACC. Restriction on age at diagnosis or strength of the family history would fail to identify mutation carriers.

Prevalence of TP53 germ line mutations in young Pakistani breast cancer patients

Women from Pakistan and India are more often diagnosed with early-onset breast cancer than Caucasian women. Given that only 12% of Pakistani women diagnosed with breast cancer at or before 30 years of age have previously been shown to harbor germ line mutations in the breast cancer susceptibility genes BRCA1 and BRCA2, the genetic causes of the majority of early-onset cases are unexplained. Since germ line mutations in the tumor suppressor gene TP53 predispose women to early-onset breast cancer, we assessed the prevalence of TP53 mutations in 105 early-onset breast cancer patients from Pakistan, who had previously been found to be negative for BRCA1 and BRCA2 germ line mutations. The patient group included 67 women diagnosed with early-onset breast cancer at or before age 30 with no family history of breast or ovarian cancer (EO30NFH group) and 38 women diagnosed with breast cancer at or before age 40 with one or more first- or second-degree relatives with breast or ovarian cancer (EO40FH group). Mutation analysis of the complete TP53 coding region was performed using denaturing high-performance liquid chromatography analysis, followed by DNA sequencing of variant fragments. One deleterious mutation, c.499-500delCA in exon 5, was identified in the 105 breast cancer patients (1%). This mutation is novel in the germ line and has not been described in other populations. It was detected in a 28-year-old patient with no family history of breast or ovarian cancer. This mutation is rare as it was not detected in additional 157 recently recruited non-BRCA1 and non-BRCA2-associated early-onset breast cancer patients. Our findings show that TP53 mutations may account for a minimal portion of early-onset breast cancer in Pakistan.

Li-Fraumeni-like syndrome associated with a large BRCA1 intragenic deletion

Background

Li-Fraumeni (LFS) and Li-Fraumeni-like (LFL) syndromes are associated to germline TP53 mutations, and are characterized by the development of central nervous system tumors, sarcomas, adrenocortical carcinomas, and other early-onset tumors. Due to the high frequency of breast cancer in LFS/LFL families, these syndromes clinically overlap with hereditary breast cancer (HBC). Germline point mutations in BRCA1, BRCA2, and TP53 genes are associated with high risk of breast cancer. Large rearrangements involving these genes are also implicated in the HBC phenotype.

Methods

We have screened DNA copy number changes by MLPA on BRCA1, BRCA2, and TP53 genes in 23 breast cancer patients with a clinical diagnosis consistent with LFS/LFL; most of these families also met the clinical criteria for other HBC syndromes.

Results

We found no DNA copy number alterations in the BRCA2 and TP53 genes, but we detected in one patient a 36.4 Kb BRCA1 microdeletion, confirmed and further mapped by array-CGH, encompassing exons 9–19. Breakpoints sequencing analysis suggests that this rearrangement was mediated by flanking Alu sequences.

Conclusion

This is the first description of a germline intragenic BRCA1 deletion in a breast cancer patient with a family history consistent with both LFL and HBC syndromes. Our results show that large rearrangements in these known cancer predisposition genes occur, but are not a frequent cause of cancer susceptibility.

Familial aggregation of urinary tract and bone tumors: searching for a syndrome

Positive family anamnesis is an important risk factor for cancer, and therefore further investigations need to be done if familial aggregation of cancer is observed. Due to a rare combination of urinary tract and bone tumors occurring in the family presented herein we hypothesized a hereditary predisposition and thus, Li-Fraumeni syndrome was considered to be the most likely differential diagnosis. To confirm Li-Fraumeni syndrome, we set out to investigate this case by analyzing the tumor suppressor gene p53. However, taking into account all the diagnostic results obtained, Li-Fraumeni syndrome could not be confirmed, but there is still uncertainty regarding a definitive diagnosis.

Late onset Li-Fraumeni Syndrome with bilateral breast cancer and other malignancies: case report and review of the literature

Background

Li-Fraumeni-Syndrome (LFS) is an autosomal-dominant, inherited tumour predisposition syndrome associated with heterozygous germline mutations in the TP53 gene. Patients with LFS are at a high risk to develop early-onset breast cancer and multiple malignancies, among which sarcomas are the most common. A high incidence of childhood tumours and close to 100% penetrance has been described. Knowledge of the genetic status of the TP53 gene in these patients is critical not only due to the increased risk of malignancies, but also because of the therapeutic implications, since a higher rate of radiation-induced secondary tumours in these patients has been observed.

Case report

We report a patient with LFS harbouring heterozygous, pathogenic TP53 germline mutation, who was affected by four synchronous malignancies at the age of 40: a myxofibrosarcoma of the right upper arm, bilateral breast cancer and a periadrenal liposarcoma. Radiological treatments and a surveillance program were adjusted according to recommendations for LFS patients.

Conclusion

Management of tumour treatment of patients with LFS is different to the general population because of their risk for secondary cancers in the radiation field. Screening procedures should take a possibly elevated risk for radiation induced cancer into account.

Gastric cancer in individuals with Li-Fraumeni syndrome

PURPOSE

Li-Fraumeni syndrome is a rare hereditary cancer syndrome associated with germline mutations in the TP53 gene. Although sarcomas, brain tumors, leukemias, breast and adrenal cortical carcinomas are typically recognized as Li-Fraumeni syndrome-associated tumors, the occurrence of gastrointestinal neoplasms has not been fully evaluated. In this analysis, we investigated the frequency and characteristics of gastric cancer in Li-Fraumeni syndrome.

METHODS

Pedigrees and medical records of 62 TP53 mutation-positive families were retrospectively reviewed from the Dana-Farber/National Cancer Institute Li-Fraumeni syndrome registry. We identified subjects with gastric cancer documented either by pathology report or death certificate and performed pathology review of the available specimens.

RESULTS

Among 62 TP53 mutation-positive families, there were 429 cancer-affected individuals. Gastric cancer was the diagnosis in the lineages of 21 (4.9%) subjects from 14 families (22.6%). The mean and median ages at gastric cancer diagnosis were 43 and 36 years, respectively (range: 24-74 years), significantly younger compared with the median age at diagnosis in the general population based on Surveillance Epidemiology and End Results data (71 years). Five (8.1%) families reported two or more cases of gastric cancer, and six (9.7%) families had cases of both colorectal and gastric cancers. No association was seen between phenotype and type/location of the TP53 mutations. Pathology review of the available tumors revealed both intestinal and diffuse histologies.

CONCLUSIONS

Early-onset gastric cancer seems to be a component of Li-Fraumeni syndrome, suggesting the need for early and regular endoscopic screening in individuals with germline TP53 mutations, particularly among those with a family history of gastric cancer.

Genetics, genomics, and cancer risk assessment: State of the Art and Future Directions in the Era of Personalized Medicine

Scientific and technologic advances are revolutionizing our approach to genetic cancer risk assessment, cancer screening and prevention, and targeted therapy, fulfilling the promise of personalized medicine. In this monograph, we review the evolution of scientific discovery in cancer genetics and genomics, and describe current approaches, benefits, and barriers to the translation of this information to the practice of preventive medicine. Summaries of known hereditary cancer syndromes and highly penetrant genes are provided and contrasted with recently discovered genomic variants associated with modest increases in cancer risk. We describe the scope of knowledge, tools, and expertise required for the translation of complex genetic and genomic test information into clinical practice. The challenges of genomic counseling include the need for genetics and genomics professional education and multidisciplinary team training, the need for evidence-based information regarding the clinical utility of testing for genomic variants, the potential dangers posed by premature marketing of first-generation genomic profiles, and the need for new clinical models to improve access to and responsible communication of complex disease risk information. We conclude that given the experiences and lessons learned in the genetics era, the multidisciplinary model of genetic cancer risk assessment and management will serve as a solid foundation to support the integration of personalized genomic information into the practice of cancer medicine.

Map making in the 21st century: charting breast cancer susceptibility pathways in rodent models

Genetic factors play an important role in determining risk and resistance to increased breast cancer. Recent technological advances have made it possible to analyze hundreds of thousands of single nucleotide polymorphisms in large-scale association studies in humans and have resulted in identification of alleles in over 20 genes that influence breast cancer risk. Despite these advances, the challenge remains in identifying what the functional polymorphisms are that confer the increased risk, and how these genetic variants interact with each other and with environmental factors. In rodents, the incidence of mammary tumors varies among strains, such that they can provide alternate ideas for candidate pathways involved in humans. Mapping studies in animals have unearthed numerous loci for breast cancer susceptibility that have been validated in human populations. In a reciprocal manner, knockin and knockout mice have been used to validate the tumorigenicity of risk alleles found in population studies. Rodent studies also underscore the complexity of interactions among alleles. The fact that genes affecting risk and resistance to mammary tumors in rodents depend greatly upon the carcinogenic challenge emphasizes the importance of gene x environment interactions. The challenge to rodent geneticists now is to capitalize on the ability to control the genetics and environment in rodent models of tumorigenesis to better understand the biology of breast cancer development, to identify those polymorphisms most relevant to human susceptibility and to identify compensatory pathways that can be targeted for improved prevention in women at highest risk of developing breast cancer.

Clinical management of hereditary breast cancer syndromes

Over the past 15 years there has been substantial improvement in the understanding of hereditary breast cancer. Germline genetic testing for mutations in BRCA1, BRCA2, PTEN and TP53 allows for the identification of individuals at increased risk for breast, ovarian and other cancers. Advances in screening, prevention and treatment have led to improved clinical management which is best defined for BRCA1 and BRCA2 mutation carriers. The addition of screening techniques such as breast magnetic resonance imaging has been shown to lead to earlier detection. Risk-reducing salpingo-oophorectomy leads to a reduction in the risk of both ovarian cancer and breast cancer and also is associated with an improvement in overall survival. BRCA1/2 mutation status may be applicable to systemic therapy decisions. Preclinical and early clinical research suggests that specific classes of chemotherapy may be more effective in mutation carriers. Finally, PARP inhibitors represent a novel therapeutic strategy that exploits the weaknesses of BRCA1/2-associated malignancies.

Regular surveillance for Li-Fraumeni Syndrome: advice, adherence and perceived benefits

Li Fraumeni Syndrome (LFS) is a hereditary cancer syndrome characterized by a high risk of developing various types of cancer from birth through late adulthood. Clinical benefits of surveillance for LFS are limited. The aim of this study is to investigate which advice for regular surveillance, if any, is given to high risk LFS individuals, adherence to that advice, and any psychological gain or burden derived from surveillance. Fifty-five high risk individuals (proven carriers and those at 50% risk) from families with a p53 germline mutation were invited to participate, of whom 82% completed a self-report questionnaire assessing advice for regular surveillance, compliance, perceived benefits and barriers of screening and LFS-related distress (IES) and worries (CWS). In total, 71% of the high risk family members received advice to undergo regular surveillance for LFS. The majority (78%) reported adherence with the recommended advice. All high risk women aged 25 or older reported having been advised to undergo annual breast cancer surveillance (n = 11), of whom 64% (n = 7) in specific received advice to undergo a mammography. Seventy-eight percent of respondents indicated having received tailored surveillance advice based on family cancer history. The large majority of respondents believed in the value of surveillance to detect tumors at an early stage (90%) and reported that it gave them a sense of control (84%) and security (70%). Despite its limited clinical benefits, the majority of high risk LFS family are advised to undergo, and are adherent to, and report psychological benefit from, regular surveillance programs.

Joint effects of germ-line TP53 mutation, MDM2 SNP309, and gender on cancer risk in family studies of Li-Fraumeni syndrome

Li-Fraumeni syndrome (LFS) is a rare familial cancer syndrome characterized by early cancer onset, diverse tumor types, and multiple primary tumors. Germ-line TP53 mutations have been identified in most LFS families. A high-frequency single-nucleotide polymorphism, SNP309 (rs2279744), in MDM2 was recently confirmed to be a modifier of cancer risk in several case-series studies: substantially earlier cancer onset was observed in SNP309 G-allele carriers than in wild-type individuals by 7-16 years. However, cancer risk analyses that jointly account for measured hereditary TP53 mutations and MDM2 SNP309 have not been systematically investigated in familial cases. Here, we determined the combined effects of measured TP53 mutations, MDM2 SNP309, and gender and their interactions simultaneously in LFS families. We used the method that is designed for extended pedigrees and structured for age-specific risk models based on Cox proportional hazards regression. We analyzed the cancer incidence in 19 extended pedigrees with germ-line TP53 mutations ascertained through the clinical LFS phenotype. The dataset consisted of 463 individuals with 129 TP53 mutation carriers. Our analyses showed that the TP53 germ-line mutation and its interaction with gender were strongly associated with familial cancer incidence and that the association between MDM2 SNP309 and increased cancer risk was modest. In contrast with several case-series studies, the interaction between MDM2 SNP309 and TP53 mutation was not statistically significant in our LFS family cohort. Our results showed that SNP309 G-alleles were associated with accelerated tumor formation in both carriers and non-carriers of germ-line TP53 mutations.

A common molecular mechanism underlies two phenotypically distinct 17p13.1 microdeletion syndromes

DNA copy-number variations (CNVs) underlie many neuropsychiatric conditions, but they have been less studied in cancer. We report the association of a 17p13.1 CNV, childhood-onset developmental delay (DD), and cancer. Through a screen of over 4000 patients with diverse diagnoses, we identified eight probands harboring microdeletions at TP53 (17p13.1). We used a purpose-built high-resolution array with 93.75% breakpoint accuracy to fine map these microdeletions. Four patients were found to have a common phenotype including DD, hypotonia, and hand and foot abnormalities, constituting a unique syndrome. Notably, these patients were not affected with cancer. Moreover, none of the TP53-deletion patients affected with cancer (n = 4) had neurocognitive impairments. DD patients have larger deletions, which encompass but do not disrupt TP53, whereas cancer-affected patients harbor CNVs with at least one breakpoint within TP53. Most 17p13.1 deletions arise by Alu-mediated nonallelic homologous recombination. Furthermore, we identify a critical genomic region associated with DD and containing six underexpressed genes. We conclude that, although they overlap, 17p13.1 CNVs are associated with distinct phenotypes depending on the position of the breakpoint with respect to TP53. Further, detailed characterization of breakpoints revealed a common formation signature. Future studies should consider whether other loci in the genome also give rise to phenotypically distinct disorders by means of a common mechanism, resulting in a similar formation signature.

Breast cancer in young women

Although uncommon, breast cancer in young women is worthy of special attention due to the unique and complex issues that are raised. This article reviews specific challenges associated with the care of younger breast cancer patients, which include fertility preservation, management of inherited breast cancer syndromes, maintenance of bone health, secondary prevention, and attention to psychosocial issues.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Li-Fraumeni syndrome in a Turkish family

Li-Fraumeni syndrome (LFS) is one of the familial cancers characterized by different tumors and hereditary TP53 mutations. The adrenocortical carcinoma (ACC) association with acute leukemia is unusual in childhood, even in LFS. The authors here present a family with pR337P mutation in TP53 gene who had a child with acute lymphoblastic leukemia (ALL) and associated adrenocortical carcinoma as a case 1 and his cousin with brain tumor as a case 2. A hereditary TP53 mutation supported the diagnosis of LFS in this family. The patients had many difficulties in treatment strategies and succumbed to death. The availability of a reliable molecular marker to detect the R337P TP53 mutation allows the rapid identification of carriers in families that have a child with ACC. Once identified, carriers could be screened for early detection of ACC by imaging and endocrine studies and should be given psychological support to prevent anxiety for death. Whether early detection of ACC will reduce the mortality in these patients remains to be determined.

Genetic modeling of Li-Fraumeni syndrome in zebrafish

Li-Fraumeni syndrome (LFS) is a highly penetrant, autosomal dominant, human familial cancer predisposition. Although a key role for the tumor suppressor p53 has been implicated in LFS, the genetic and cellular mechanisms underpinning this disease remain unknown. Therefore, modeling LFS in a vertebrate system that is accessible to both large-scale genetic screens and in vivo cell biological studies will facilitate the in vivo dissection of disease mechanisms, help identify candidate genes, and spur the discovery of therapeutic compounds. Here, we describe a forward genetic screen in zebrafish embryos that was used to identify LFS candidate genes, which yielded a p53 mutant (p53(I166T)) that as an adult develops tumors, predominantly sarcomas, with 100% penetrance. As in humans with LFS, tumors arise in heterozygotes and display loss of heterozygosity (LOH). This report of LOH indicates that Knudson's two-hit hypothesis, a hallmark of human autosomal dominant cancer syndromes, can be modeled in zebrafish. Furthermore, as with some LFS mutations, the zebrafish p53(I166T) allele is a loss-of-function allele with dominant-negative activity in vivo. Additionally, we demonstrate that the p53 regulatory pathway, including Mdm2 regulation, is evolutionarily conserved in zebrafish, providing a bona fide biological context in which to systematically uncover novel modifier genes and therapeutic agents for human LFS.

Germline mutations and polymorphisms in the origins of cancers in women

Several female malignancies including breast, ovarian, and endometrial cancers can be characterized based on known somatic and germline mutations. Initiation and propagation of tumors reflect underlying genomic alterations such as mutations, polymorphisms, and copy number variations found in genes of multiple cellular pathways. The contributions of any single genetic variation or mutation in a population depend on its frequency and penetrance as well as tissue-specific functionality. Genome wide association studies, fluorescence in situ hybridization, comparative genomic hybridization, and candidate gene studies have enumerated genetic contributors to cancers in women. These include p53, BRCA1, BRCA2, STK11, PTEN, CHEK2, ATM, BRIP1, PALB2, FGFR2, TGFB1, MDM2, MDM4 as well as several other chromosomal loci. Based on the heterogeneity within a specific tumor type, a combination of genomic alterations defines the cancer subtype, biologic behavior, and in some cases, response to therapeutics. Consideration of tumor heterogeneity is therefore important in the critical analysis of gene associations in cancer.

Effects of measured susceptibility genes on cancer risk in family studies

Numerous family studies have been performed to assess the associations between cancer incidence and genetic and non-genetic risk factors and to quantitatively evaluate the cancer risk attributable to these factors. However, mathematical models that account for a measured hereditary susceptibility gene have not been fully explored in family studies. In this report, we proposed statistical approaches to precisely model a measured susceptibility gene fitted to family data and simultaneously determine the combined effects of individual risk factors and their interactions. Our approaches are structured for age-specific risk models based on Cox proportional hazards regression methods. They are useful for analyses of families and extended pedigrees in which measured risk genotypes are segregated within the family and are robust even when the genotypes are available only in some members of a family. We exemplified these methods by analyzing six extended pedigrees ascertained through soft-tissue sarcoma patients with p53 germ-line mutations. Our analyses showed that germ-line p53 mutations and sex had significant interaction effects on cancer risk. Our proposed methods in family studies are accurate and robust for assessing age-specific cancer risk attributable to a measured hereditary susceptibility gene, providing valuable inferences for genetic counseling and clinical management.

Identification of a novel germ-line mutation in the TP53 gene in a Mexican family with Li-Fraumeni syndrome

BACKGROUND

Germ-line mutations of the TP53 gene are known to cause Li-Fraumeni syndrome, an autosomal, dominantly inherited, high-penetrance cancer-predisposition syndrome characterized by the occurrence of a variety of cancers, mainly soft tissue sarcomas, adrenocortical carcinoma, leukemia, breast cancer, and brain tumors.

METHODS

Mutation analysis was based on Denaturing high performance liquid chromatography (DHPLC) screening of exons 2-11 of the TP53 gene, sequencing, and cloning of DNA obtained from peripheral blood lymphocytes.

RESULTS

We report herein on Li Fraumeni syndrome in a family whose members are carriers of a novel TP53 gene mutation at exon 4. The mutation comprises an insertion/duplication of seven nucleotides affecting codon 110 and generating a new nucleotide sequence and a premature stop codon at position 150. With this mutation, the p53 protein that should be translated lacks the majority of the DNA binding domain.

CONCLUSION

To our knowledge, this specific alteration has not been reported previously, but we believe it is the cause of the Li-Fraumeni syndrome in this family.

TP53 germline mutations in Portugal and genetic modifiers of age at cancer onset

The Li-Fraumeni syndrome (LFS) is a rare, autosomal dominant disease caused by TP53 germline mutations. This study aimed to characterize the TP53 mutational spectrum in patients suspected to have LFS in Portugal and to evaluate the influence of the MDM2-SNP309 and TP53-72Arg variants and of telomere length on age of tumor onset. Probands were primarily selected using the classical LFS criteria (two cases) or the more sensitive Chompret Li-Fraumeni-like (LFL) criteria (13 cases), but 12 additional patients that did not comply with those LFS or LFL criteria were included in the analysis based on clinical suspicion (LFS suspects). Nine of the 27 probands (33.3%) presented germline TP53 mutations, two of them occurring de novo and two of them being novel. Three of the nine TP53 mutations were found in families that did not comply with any of the commonly used criteria for TP53 testing, leaving room to recommend the use of less stringent criteria. An association was found between the presence of the TP53-72Arg (but not the MDM2-SNP309) variant and earlier age of onset in TP53 carriers. A negative correlation between telomere length and age of cancer onset was found in patients with germline TP53 mutation, whereas no such correlation was found in controls or in patients with wild-type TP53.

Childhood predictive genetic testing for Li-Fraumeni syndrome

Presymptomatic genetic testing in childhood for adult onset conditions is generally discouraged as it does not directly benefit the child and removes their autonomy. In certain cancer prone conditions such as Familial Adenomatous Polyposis and Von Hippel Lindau disease there are risks of disease in childhood and benefit to children not inheriting a mutation in being able to forego unpleasant screening tests. Li-Fraumeni syndrome caused by constitutional TP53 mutations there are also implications in childhood with a risk of around 20% of a childhood malignancy. However, as yet no evidence based surveillance programme has been identified. We describe our experience of childhood testing for four children in two Li-Fraumeni families caused by TP53 mutations.

Beyond Li Fraumeni Syndrome: clinical characteristics of families with p53 germline mutations

PURPOSE

A clinical testing cohort was used to gain a broader understanding of the spectrum of tumors associated with germline p53 mutations to aid clinicians in identifying high-risk families.

PATIENTS AND METHODS

Full sequencing of the coding exons (2 to 11) and associated splice junctions of the p53 gene was performed on 525 consecutive patients whose blood samples were submitted for diagnostic testing. Clinical features of p53 germline carriers in this cohort were characterized, clinical referral schemes based on reported p53-associated family phenotypes were evaluated, and practical mutation prevalence tables were generated.

RESULTS

Mutations were identified in 91 (17%) of 525 patients submitted for testing. All families with a p53 mutation had at least one family member with a sarcoma, breast, brain, or adrenocortical carcinoma (ACC). Every individual with a choroid plexus tumor (eight of eight) and 14 of 21 individuals with a childhood ACC had a mutation regardless of family history. Based on reported personal and family history, 95% of patients (71 of 75) with a mutation met either classic Li Fraumeni syndrome (LFS) or Chompret criteria. A simplified prevalence table provides a concise summary of individual and family characteristics associated with p53 mutations.

CONCLUSION

This is, to our knowledge, the largest single report of diagnostic testing for germline p53 mutations, yielding practical mutation prevalence tables and suggesting clinical utility of classic LFS and Chompret criteria for identifying a subset of cancer-prone families with p53 germline mutations, with important implications for diagnosis and management.

Molecular markers and the pathogenesis of adrenocortical cancer

Adrenal tumors are common, with an estimated incidence of 7.3% in autopsy cases, while adrenocortical carcinomas (ACCs) are rare, with an estimated prevalence of 4-12 per million population. Because the prognoses for adrenocortical adenomas (ACAs) and ACCs are vastly different, it is important to be able to accurately differentiate the two tumor types. Advancement in the understanding of the pathophysiology of ACCs is essential for the development of more sensitive means of diagnosis and treatment, resulting in better clinical outcome. Adrenocortical tumors (ACTs) occur as a component of several hereditary tumor syndromes, which include the Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia 1, Carney complex, and congenital adrenal hyperplasia. The genes involved in these syndromes have also been shown to play a role in the pathogenesis of sporadic ACTs. The adrenocorticotropic hormone-cAMP-protein kinase A and Wnt pathways are also implicated in adrenocortical tumorigenesis. The aim of this review is to summarize the current knowledge on the molecular mechanisms involved in adrenocortical tumorigenesis, including results of comparative genomic hybridization, loss of heterozygosity, and microarray gene-expression profiling studies.

Genetic counseling and testing for common hereditary breast cancer syndromes: a paper from the 2007 William Beaumont hospital symposium on molecular pathology

Throughout the past 15 years, the identification of several genes associated with hereditary breast cancer has fueled the growth of clinical genetic counseling and testing services. In addition, increased knowledge of the genetic and molecular pathways of the known hereditary breast cancer genes, as well as an increased understanding of the impact of testing on individuals has added to the ability to identify, manage, and provide psychosocial support for mutation carriers. This review provides an overview of the clinical features, cancer risks, causative genes, and management for hereditary breast and ovarian cancer syndrome, Cowden syndrome, and Li-Fraumeni syndrome. This article summarizes the genetic counseling process and genetic test result interpretation, including a review of the key elements involved in the provision of risk assessment and informed consent, as well as a review of the risks, benefits, and limitations of cancer susceptibility genetic testing.

Lower breast cancer survival in mothers of children with a malignancy: a national study

As it is unclear if hereditary factors affect breast cancer survival, this was compared using fertility and cancer registry data, among all women so diagnosed during 1961–1999 in Sweden, having a child with childhood cancer (⩽20 years of age; n=254) and with that of other women (n=74 781). Those having a child with a childhood malignancy had a significantly worse survival than other women, relative risk (RR)=1.25, 95% CI 1.02–1.55, P<0.04, adjusted for age at diagnosis, year of diagnosis, parity and time since last pregnancy. Childhood sarcomas or acute myeloid leukaemia seemed to be most associated with a worse survival in the mother (RR=1.38 and 1.69, respectively). The lower survival of the mother was present for breast cancer diagnosed both before and after 50 years of age. The Li–Fraumeni syndrome and possibly other genetic disorders may lower breast cancer survival.

p53 Testing for Li-Fraumeni and Li-Fraumeni-like syndromes

Li-Fraumeni Syndrome (LFS; OMIM #151623) is an autosomal dominant cancer predisposition syndrome characterized by early onset tumors including sarcomas, breast cancer, leukemia, brain tumors, and adrenocortical carcinoma. Li-Fraumeni syndrome is primarily attributed to germline mutations in the p53 tumor suppressor gene, which encodes tumor protein 53. In addition to germline p53 mutations, the p53 gene is the most commonly mutated gene in human cancers, with as much as 50% of tumors containing somatic p53 mutations. This unit provides a protocol to perform germline mutation analysis of the p53 gene. The protocol includes steps for amplification and sequencing of the entire coding region of the p53 gene (exons 2 to 11). The protocol was designed for detecting germline alterations from DNA extracted from blood; however, with some additional optimization, it could also be used to detect somatic mutations in DNA extracted from tumors.

An information-theoretic analysis of genetics, gender and age in cancer patients

Germline genetics, gender and hormonal-signaling pathways are all well described modifiers of cancer risk and progression. Although an improved understanding of how germline genetic variants interact with other cancer risk factors may allow better prevention and treatment of human cancer, measuring and quantifying these interactions is challenging. In other areas of research, Information Theory has been used to quantitatively describe similar multivariate interactions. We implemented a novel information-theoretic analysis to measure the joint effect of a high frequency germline genetic variant of the p53 tumor suppressor pathway (MDM2 SNP309 T/G) and gender on clinical cancer phenotypes. This analysis quantitatively describes synergistic interactions among gender, the MDM2 SNP309 locus, and the age of onset of tumorigenesis in p53 mutation carriers. These results offer a molecular and genetic basis for the observed sexual dimorphism of cancer risk in p53 mutation carriers and a model is proposed that suggests a novel cancer prevention strategy for p53 mutation carriers.