Li-Fraumeni-like Research Articles

Whole exome sequencing identified a novel POT1 variant as a candidate pathogenic allele underlying a Li-Fraumeni-like family.

Li-Fraumeni syndrome (LFS) and Li-Fraumeni-like (LFL) syndrome are rare hereditary diseases characterized by predisposition to a diverse spectrum of cancer types, primarily sarcoma. The pathogenic variants underlying the majority of LFL cases remain to be explored. We performed whole-exome sequencing (WES) on 13 core members of a large LFL family with highly aggregated incidences of cancers, including cases with sarcoma, non-small cell lung cancer and cardiac angiosarcoma, and conducted a comprehensive literature review of candidate gene associations in LFS/LFL syndromes or sarcoma to identify potential pathogenic germline variants. No germline variants in the best-known LFL/LFS-associated gene TP53 were detected. Of all the genes associated with LFS/LFL or sarcoma that we have surveyed, we identified a novel p.P35L germline variant in POT1 (protection of telomeres 1). Germline and somatic alterations in POT1 have been implicated in a series of familial cancers, including angiosarcoma, glioma, melanoma and colorectal cancer. This particular variant is located in the telomere-binding OB1 domain, which is important in maintaining the proper telomere length, and showed high conservation across different POT1 orthologues. No record of the variant was found in any of the 1000 genomes, ExAC, gnomAD, dpSNP and COSMIC databases. Prediction algorithms and in silico structural analysis suggested completely disrupted protein structure and function of POT1 in the presence of this mutation. Leveraging WES, we identified a novel germline risk allele, p.P35L in POT1, that likely predisposes to LFL syndrome. Our results support the routine testing of POT1 and other LFL/LFS-associated genes in the risk populations to enable early cancer diagnosis, prevention and intervention.

TP53 Pathogenic Variants in Early-Onset Breast Cancer Patients Fulfilling Hereditary Breast and Ovary Cancer and Li-Fraumeni-like Syndromes.

TP53 gene mutation is the most common genetic alteration in human malignant tumors and is mainly responsible for Li-Fraumeni syndrome. Among the several cancers related to this syndrome, breast cancer (BC) is the most common. The TP53 p.R337H germline pathogenic variant is highly prevalent in Brazil’s South and Southeast regions, accounting for 0.3% of the general population. We investigated the prevalence of TP53 germline pathogenic variants in a cohort of 83 BC patients from the Midwest Brazilian region. All patients met the clinical criteria for hereditary breast and ovarian cancer syndrome (HBOC) and were negative for BRCA1 and BRCA2 mutations. Moreover, 40 index patients fulfilled HBOC and the Li-Fraumeni-like (LFL) syndromes criteria. The samples were tested using next generation sequencing for TP53. Three patients harbored TP53 missense pathogenic variants (p.Arg248Gln, p.Arg337His, and p.Arg337Cys), confirmed by Sanger sequencing. One (1.2%) patient showed a large TP53 deletion (exons 2–11), which was also confirmed. The p.R337H variant was detected in only one patient. In conclusion, four (4.8%) early-onset breast cancer patients fulfilling the HBOC and LFL syndromes presented TP53 pathogenic variants, confirming the relevance of genetic tests in this group of patients. In contrast to other Brazilian regions, TP53 p.R337H variant appeared with low prevalence.

Radiotherapy-induced malignancies in breast cancer patients with TP53 pathogenic germline variants (Li-Fraumeni syndrome).

The risk of radiotherapy-induced malignancies (RIMs) is a concern when treating Li-Fraumeni syndrome (LFS) or Li-Fraumeni Like (LFL) patients. However, the type of TP53 pathogenic germline variant may possibly influence this risk. TP53 p.R337H mutation is particularly prevalent in Brazil. We aimed to evaluate the outcomes of patients with pathogenic TP53 variants treated for localized breast cancer in a Brazilian cohort. We evaluated retrospectively a cohort of patients with germline TP53 pathogenic variants treated for localized breast cancer between December 1999 and October 2017. All patients were followed by the Hereditary Cancer Group of an academic cancer center. Our primary objective was to evaluate the occurrence of RIMs after adjuvant radiotherapy. Sixteen patients were evaluated; 10 (62.5%) had a germline TP53 p.R337H pathogenic variant. Median age was 39.8years. Thirteen patients had invasive ductal carcinoma: 8 (61.5%) were hormone receptor-positive; 6 (46.1%), human epithelial growth factor receptor 2 (HER2)-amplified. Three patients had ductal carcinoma in situ. Most patients (N = 12/16, 75%) received adjuvant radiotherapy. After a median follow-up of 52.5months, 2 patients (2/12, 16.6%) had RIMs. One had a fibrosarcoma and the other, a low-grade leiomyosarcoma. In the group treated with radiotherapy, one distant recurrence was diagnosed (1/12), and no loco-regional recurrence occurred. Among 4 patients who did not receive radiotherapy, 2 presented with loco-regional recurrence. In this cohort of patients with LFS enriched in TP53 p.R337H pathogenic variant, the incidence of RIMs after treatment of localized breast cancer was lower than previous literature. Nevertheless, rates of RIMs were still alarming. Early molecular diagnosis and careful evaluation of treatment risks and benefits are essential for these patients.

TP53 variants of uncertain significance: increasing challenges in variant interpretation and genetic counseling.

Li-Fraumeni syndrome (LFS) and Li-Fraumeni Like (LFL) are autosomal dominant cancer predisposition syndromes caused by pathogenic germline variants in the TP53 gene. Recent studies have shown that the incorporation of next-generation sequencing by using multigene panels in clinical practice has resulted in the frequent identification of variants of uncertain significance (VUS). Given that there is no established medical management for VUS carriers, the identification of these variants may cause confusion and anxiety for both patients and practitioners. Herein, we aimed to verify VUS frequency and review VUS classification and interpretation in 1844 patients submitted for comprehensive germline TP53 testing independent of clinical criteria. Variant characterization was done assessing clinical information whenever available, variant frequency in population databases, pathogenicity predictions using in silico tools and previous functional studies. All variants were classified based on the guidelines proposed by the American College of Medical Genetics and Genomics (2015) and by the Sherloc framework (2017). Of the twelve VUS (0.65%) identified in TP53, two were classified as likely pathogenic and two were classified as likely benign after re-evaluation, potentially resulting in significant management modification for the proband and relatives. This report cases highlights the challenges and impact of TP53 variant interpretation especially when there is no clear LFS/LFL phenotype.

The wide spectrum of POT1 gene variants correlates with multiple cancer types.

The POT1 protein binds and protects telomeres. Germline variants in the POT1 gene have recently been shown to be associated with risk of developing tumors in different tissues such as familial chronic lymphocytic leukemia, colorectal, glioma and melanoma tumors. Recently, we uncovered a variant in the POT1 gene (p.R117C) as causative of familial cardiac angiosarcomas (CAS) in Li-Fraumeni-like (LFL) syndrome families. Our in silico studies predicted that this protein had lost the ability to interact with TPP1 and single-stranded DNA. In vitro studies corroborated this prediction and showed that this lack of function leads to abnormally long telomeres. To better understand the POT1 gene and its role with tumorigenesis, we extended the study to LFL (with and without members affected with angiosarcomas (AS)) and sporadic AS and cardiac sarcomas. We found POT1 variants in the 20% of the families with members affected with AS and 10% of sporadic AS and sarcomas. In silico studies predicted that these new variants were damaging in the same manner as previously described for the POT1 p.R117C variants. The wide spectrum of variants in the POT1 gene leading to tumorigenesis in different tissues demonstrates its general importance. Study of the POT1 gene should be considered as routine diagnostic in these cancers.

The Inherited p53 Mutation in the Brazilian Population

A common criticism of studying rare diseases is the often-limited relevance of the findings to human health. Here, we review ∼15 years of research into an unusual germline TP53 mutation (p.R337H) that began with its detection in children with adrenocortical carcinoma (ACC), a remarkably rare childhood cancer that is associated with poor prognosis. We have come to learn that the p.R337H mutation exists at a very high frequency in Southern and Southeastern Brazil, occurring in one of 375 individuals within a total population of ∼100 million. Moreover, it has been determined that carriers of this founder mutation display variable tumor susceptibility, ranging from isolated cases of pediatric ACC to Li-Fraumeni or Li-Fraumeni-like (LFL) syndromes, thus representing a significant medical issue for this country. Studying the biochemical and molecular consequences of this mutation on p53 tumor-suppressor activity, as well as the putative additional genetic alterations that cooperate with this mutation, is advancing our understanding of how p53 functions in tumor suppression in general. These studies, which originated with a rare childhood tumor, are providing important information for guiding genetic counselors and physicians in treating their patients and are already providing clinical benefit.

Rare germline variant (rs78378222) in the TP53 3' UTR: Evidence for a new mechanism of cancer predisposition in Li-Fraumeni syndrome

Germline mutations in TP53 are the underlying defects in Li-Fraumeni syndrome (LFS) and its variant, Li-Fraumeni-like (LFL) Syndrome, autosomal dominant disorders that are characterized by predisposition to multiple early onset cancers. Here, we identified rs78378222 (A > C), a rare variant that is located in the 3' untranslated region (3' UTR) of TP53, in 7 probands (5.4%) of a cohort from LFS/LFL patients without TP53 germline mutations in the coding regions. To support its association with the LFS/LFL phenotype, we assessed p53 expression in tumor specimens and fibroblasts from rs78378222[C] carriers. Additionally, we investigated using in silico tools the evolutionary conservation and whether rs78378222[C] affects microRNA (miRNA) binding sites in the 3' UTR of TP53 mRNA. We found lower p53 protein levels in biological samples from rs78378222[C] carriers. Additionally, we showed that rs78378222[C] could interfere with a putative target site of miR-545-3p, a novel miRNA that is predicted to directly target the 3' UTR TP53. To our knowledge, this is the first description of rs78378222[C] in LFS/LFL patients. Moreover, these findings suggest that rs78378222[C] lead to haploinsufficiency of p53, a new mechanism of carcinogenesis in LFS/LFL.

A mutation in the POT1 gene is responsible for cardiac angiosarcoma in TP53-negative Li-Fraumeni-like families.

Cardiac angiosarcoma (CAS) is a rare malignant tumour whose genetic basis is unknown. Here we show, by whole-exome sequencing of a TP53-negative Li-Fraumeni-like (LFL) family including CAS cases, that a missense variant (p.R117C) in POT1 (protection of telomeres 1) gene is responsible for CAS. The same gene alteration is found in two other LFL families with CAS, supporting the causal effect of the identified mutation. We extend the analysis to TP53-negative LFL families with no CAS and find the same mutation in a breast AS family. The mutation is recently found once in 121,324 studied alleles in ExAC server but it is not described in any other database or found in 1,520 Spanish controls. In silico structural analysis suggests how the mutation disrupts POT1 structure. Functional and in vitro studies demonstrate that carriers of the mutation show reduced telomere-bound POT1 levels, abnormally long telomeres and increased telomere fragility.

Abstract 2749: Cumulative cancer risk in the NCI Li-Fraumeni Syndrome Cohort

Abstract Background: Li-Fraumeni Syndrome (LFS) is a rare hereditary cancer predisposition syndrome characterized by the early onset of a wide range of cancers and a very high lifetime cumulative cancer risk. Despite significant progress in understanding LFS, uncertainty remains regarding the cancer incidence rates and cancer spectrum for TP53 mutation carriers. In addition, the cancer incidence for members of families meeting the clinical diagnostic criteria of LFS or Li-Fraumeni like (LFL) syndrome but in which no TP53 mutation has been identified (TP53- families) has not been established. Methods: The NCI's LFS Study (NCT01443468) is a natural history study that opened to accrual in August 2011. Inclusion criteria include LFS or LFL syndrome; a germline TP53 mutation; or a personal history of choroid plexus carcinoma, adrenocortical carcinoma (ACC), or ≥3 primary cancers. Participants complete a detailed family history and individual information questionnaires. Confirmation of all reported cancer diagnoses is pursued. Results: Of the 122 families enrolled to date, 95 families have a germline TP53 mutation (TP53+ families) and 27 are TP53-families. TP53+ families: 243 mutation carriers from 95 mutation-positive families were included in the cancer risk estimates. The cumulative risk to first cancer diagnosis for the entire group is 43% by age 30 and close to 100 by age 70, with males having higher risk in childhood adolescence and females having higher risk starting in the 20s, mostly due to breast cancer. When examined by cancer type, the cumulative risk to age 70 is 35% for breast cancer, 16% for soft tissue sarcoma, 10% for brain cancer, 7% for bone cancer, 2% for leukemia, 2% for ACC, and 26% for others. Overall survival is approximately 80% by age 50. TP53- families: The underlying etiology contributing to cancer risk in the TP53- families is not known at this time; therefore, for the estimation of cancer risk among these families, we included all bloodline members belonging to the lineage contributing to the eligibility criteria. Among the 522 individuals from the 27 TP53- families, the cumulative risk to first cancer diagnosis is 7% by age 30 and 45% by age 70. The lifetime cumulative risk is higher for breast, brain, lung cancer, and melanoma compared with other cancer types. Overall survival is approximately 90% by age 50. Conclusion: We report the cumulative cancer incidence and overall survival among TP53 mutation carriers in TP53+ families as well as among members of TP53- families. Identification of additional causative gene(s) in TP53- families will help refine the cancer risk of family members. We are evaluating the risks of second primary cancers, and whether the rate is dependent on the type of the first cancer in all families. Citation Format: Phuong L. Mai, Philip S. Rosenberg, June A. Peter, Rosamma DeCastro, Payal P. Khincha, Jennifer T. Loud, Renee Bremer, Sharon A. Savage. Cumulative cancer risk in the NCI Li-Fraumeni Syndrome Cohort. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2749. doi:10.1158/1538-7445.AM2015-2749

Next-generation sequencing as an informing phenotype: A TP53 example.

1554 Background: Li-Fraumeni (LFS) and Li Fraumeni like (LFL) syndromes are characterised by early onset cancers such as breast cancer, leukaemia, sarcoma, brain tumours and adrenocortical carcinoma, and are defined traditionally by clinical criteria such as Chompret and Eeles. Genetic testing for TP53 germline mutation is typically undertaken in families that satisfy these clinical criteria. Next generation sequencing and gene panel testing has resulted in more frequent TP53 testing to include families that don’t meet classic testing criteria. We investigated testing criteria and result outcome in a cohort of Irish probands undergoing TP53full sequencing. Methods: All TP53 test requests processed thought the national genetic testing laboratory between 2012 and 2014 were retrospectively reviewed. Family history data including diagnoses and age at diagnosis was ascertained through hospital charts or electronic pedigrees from two adult cancer genetic services in Ireland. Additional data including reason for...

Abstract 1383: Li-Fraumeni syndrome: Clinical experience with family psycho-social issues.

Abstract Introduction: Li-Fraumeni Syndrome (LFS) is a hereditary cancer predisposition syndrome causing a range of cancers across the lifespan. About 70% of families meeting classical LFS criteria have detectable germline mutations in the TP53 gene, vs 40% of those classified as Li-Fraumeni-like (LFL). The psychological, social, and behavioral issues faced by individuals with LFS/LFL and their relatives comprise an important, but under-studied, topic. Methods: Ours is a prospective, cohort study of LFS/LFL. Enrollees are invited to participate in epidemiologic and lifestyle questionnaires, clinical evaluations, genetic counseling and testing if indicated, molecular research, cancer screening and psychosocial assessments, and, of adults, standardized, self-report, psychological assessments. Those attending clinic also have in-person interview and social assessments. Results: Two of the first five families we saw illustrate a wide range of psychosocial issues, which emerged during the social assessment and family interview.Family 1 included two adolescents with histories of osteosarcoma, and their unaffected father. Their biological mother had died a decade earlier from a different type of cancer and their father had remarried. The adolescent female proband was struggling with internal conflict, overwhelmed with trying to balance pleasing her family with the developmentally appropriate task of gaining independence. The younger male proband focused on short-term goals, seemingly finding the cancer risk personally irrelevant. The father worried about raising his children in a highly secular environment, and about how to manage their medical needs. The proband of Family 2 is a 37-year-old woman who had already survived 4 primary cancers, seen with her 2 unaffected, mutation-positive children and her mother. She was divorced from the children's father and raised them as a single mom for several years with the help of her mother until re-marrying. Pertinent psychosocial issues included an emotional and practical cut-off between the biological parents, resulting in the mother's struggle to manage her children's healthcare needs and communicate with them about their risk independent of their father, who preferred not to be involved in the medical system. Additionally, the mother's strong sense of independence created a communication barrier between her and her own mother, who felt shut out of her daughter's emotional experience despite wanting to provide support. Conclusions: There is great breadth of needs in families with LFS/LFL. Understanding the psychological, social, and behavioral issues as they are manifest in the context of LFS will help guide our efforts aimed at alleviating the psychosocial morbidity associated with this syndrome. We recommend that families receive ongoing psychosocial evaluation as an integral part of their medical management, preferable by multi-disciplinary teams. Citation Format: June A. Peters, Lindsey M. Hoskins, Phuong L. Mai, Farzana Walcott, Renee Bremer, Sharon A. Savage. Li-Fraumeni syndrome: Clinical experience with family psycho-social issues. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1383. doi:10.1158/1538-7445.AM2013-1383

Increased Oxidative Damage in Carriers of the Germline TP53 p.R337H Mutation

Germline mutations in TP53 are the underlying defect of Li-Fraumeni Syndrome (LFS) and Li-Fraumeni-like (LFL) Syndrome, autosomal dominant disorders characterized by predisposition to multiple early onset cancers. In Brazil, a variant form of LFS/LFL is commonly detected because of the high prevalence of a founder mutation at codon 337 in TP53 (p.R337H). The p53 protein exerts multiple roles in the regulation of oxidative metabolism and cellular anti-oxidant defense systems. Herein, we analyzed the redox parameters in blood samples from p.R337H mutation carriers (C, n = 17) and non-carriers (NC, n = 17). We identified a significant increase in erythrocyte GPx activity and in plasma carbonyl content,an indicator of protein oxidative damage, in mutation carriers compared to non-carriers (P = 0.048 and P = 0.035, respectively). Mutation carriers also showed a four-fold increase in plasma malondialdehyde levels, indicating increased lipid peroxidation (NC = 40.20±0.71, C = 160.5±0.88, P<0.0001). Finally, carriers showed increased total antioxidant status but a decrease in plasma ascorbic acid content. The observed imbalance could be associated with deregulated cell bioenergetics and/or with increased inflammatory stress, two effects that may result from loss of wild-type p53 function. These findings provide the first evidence that oxidative damage occurs in carriers of a germline TP53 mutation, and these may have important implications regarding our understanding of the mechanisms responsible for germline TP53 p.R337H mutation-associated carcinogenesis.

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

BackgroundLi-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.MethodsWe 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.ResultsWe 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.ConclusionThis 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.

Antioxidants and oxidative stress in patients with Li-Fraumeni-like syndrome and TP53 p.R337H mutation carriers.

e21042 Background: Germline mutations in the TP53 gene are the underlying genetic defect of Li-Fraumeni Syndrome (LFS) and its variant, Li-Fraumeni-like (LFL) Syndrome, autosomal dominant disorders characterized by predisposition to multiple early-onset cancers. More recently, p53 is emerging as an important player in redox metabolism and important enzymes involved in defenses against oxidative stress have shown to be regulated by p53, including glutathione peroxidase 1 (GPX1) and mitochondrial superoxide dismutase 2 (SOD2). The aim of the present study was to investigate the redox profile parameters in blood of p.R337H mutation carriers and non-carriers individuals. Methods: A total of 34 individuals were included in the study and they were divided in two groups: mutation carriers (n=17) and non-carriers (n=17). Antioxidant enzyme activities (SOD, CAT, GPx) and oxidative stress parameters (Protein carbonyl content, Sulfhydryl content and TBARS) were measured in plasma, erythrocytes, leukocytes and serum. Results: Erythrocyte SOD and GPx activities, two first-line players in enzimatic antioxidant defense, differed significantly between mutation carriers and non-carriers, with an increased activity in the latter (p&gt;0,05). Plasma Carbonyl content, an indicative of protein damage related to ROS overgeneration, was also increased in carriers (p=0,015). There was no significant difference between groups in all other parameters evaluated. Conclusions: Our findings suggest that TP53 p.R337H mutation carriers present different antioxidant enzyme activities and oxidative stress parameters when compared to non-carriers.

Comparable frequency of BRCA1, BRCA2 and TP53 germline mutations in a multi-ethnic Asian cohort suggests TP53 screening should be offered together with BRCA1/2 screening to early-onset breast cancer patients

IntroductionGermline TP53 mutations cause an increased risk to early-onset breast cancer in Li-Fraumeni syndrome (LFS) families and the majority of carriers identified through breast cancer cohorts have LFS or Li-Fraumeni-like (LFL) features. However, in Asia and in many low resource settings, it is challenging to obtain accurate family history and we, therefore, sought to determine whether the presence of early-onset breast cancer is an appropriate selection criteria for germline TP53 testing.MethodsA total of 100 patients with early-onset breast cancer (≤ 35 years) treated at University Malaya Medical Centre between 2003 and 2009, were analyzed for germline mutations in BRCA1, BRCA2 and TP53 by full DNA sequencing. Of the mutations identified, we examined their likely pathogenicity on the basis of prevalence in a case-control cohort, co-segregation analyses and loss of heterozygosity (LOH) in tumor tissues.ResultsWe identified 11 BRCA1 (11%) and 6 BRCA2 (6%) germline carriers among early-onset breast cancer patients. Of the 83 BRCA-negative patients, we identified four exonic variants and three intronic variants in TP53. Of these, two exonic variants are clinically relevant (E346X and p. G334_R335dup6) and two novel missense mutations (A138V and E285K) are likely to be clinically relevant, on the basis of co-segregation and loss of heterozygosity (LOH). Notably, E285K was found in two unrelated individuals and haplotype analyses suggest a founder effect. Two of the three intronic variants are likely benign based on their prevalence in a control population. Clinically relevant TP53 germline mutations were identified in three of the four patients (75%) with a family history of at least two LFS-linked cancers (breast, bone or soft tissue sarcoma, brain tumors or adrenocortical cancer); 1 of the 17 patients (6%) with a family history of breast cancer only, and 1 of the 62 patients (< 2%) with no family history of breast or LFS-linked cancers.ConclusionsOur study reports germline BRCA1, BRCA2 and TP53 mutations are found in early-onset breast cancer patients at 11%, 6% and 5% respectively, suggesting that TP53 mutation screening should be considered for these patients. However, we find that even in low resource Asian settings where family history is poorly reported, germline TP53 mutations are found predominantly among breast cancer patients with a family history of LFS-linked cancers.

Abstract 1836: Distinct tumor spectrum and age of onset in a Brazilian cohort of p.R337H TP53 mutation carriers

Abstract The Li-Fraumeni syndrome (LFS) and its variant, Li-Fraumeni-like (LFL), are associated with high risk of early-onset tumors, typically breast cancer (BC), soft tissue sarcoma (STS), adrenocortical tumor (ADR) and brain cancer (BT). The major challenge in management of LFS/LFL is to provide screening for early detection due to the wide tumor spectrum and variable age of onset. Germline mutations in the TP53 gene are the only known genetic defect underlying LFS/LFL, detected in about 70% LFS and 20% LFL families. Most mutations occur in the exons encoding the DNA binding domain of p53 protein, whereas mutations outside these exons are rare and may have partial penetrance. A particular germline mutation at codon 337 (c.1010G&amp;gt;1, p.R337H) within the C-terminal, tetramerization domain of p53 is found in 0.3% of South and Southeastern Brazilian populations due to a founder effect. The aim of this study is to compare tumor spectrum in p.R337H carriers to that of other TP53 mutations. A cohort of 345 patients from 131 families was tested for germline TP53 mutations by sequencing the coding region (exons 2-11). Deletions were assessed by Multiple Ligand Polymorphism Assay. Ninety-one patients from 35 families harbored a TP53 mutation and are followed at the Department of Oncogenetics, Hospital A.C. Camargo in São Paulo, Brazil. Mutations were detected in 35/131 families (26.5%) and 88 tumors were documented in TP53 mutation carriers. Subjects and tumor′s data were managed and analyzed with a specifically designed software (HH-LFS) running on Excel (MicrosoftTM) and Visual Basic programming. The most common mutation was the founder p.R337H mutation (FM) p.R337H, present in 54.3% (19/35) of all families. Among 91 subjects found to carry a mutation, 70.3% (64/91) carried FM. Other mutations in the DNA binding domain (OM) were detected in 27 patients and large deletions occurred in two patients. The types of tumors in carriers of FM were similar to OM. However, there were significant differences in prevalence and/or age of occurrence. In both groups, the most common tumor was breast cancer, accounting for 35.4% in FM and 25% in OM. STS were detected in 14,5% in FM and 25% in OM. Interestingly, the third most common tumor among FM was thyroid cancer (TC) (14.5%), present in 7 patients from 3 distinct families whereas no TC were found in OM (p&amp;lt;0.001). BT and ADR were found in both groups with similar frequencies. Age at diagnosis varied between the two groups. Tumors were detected in 22% of FM before the age of 20 compared to 39.5% in OM (p=0.05). Conversely, 15.2% cancers in FM were above age 60 compared to 7.9% in OM. Gender distribution showed a similar predominance of tumors in females in both groups. The tendency of FM to develop a higher proportion of adult cancers as compared to OM suggests specific screening strategies for FM group. Moreover, the high prevalence of TC advocates for anual thyroid ultrasound screening in carriers of the p.R337H mutation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1836. doi:10.1158/1538-7445.AM2011-1836

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.

Li–Fraumeni and Li–Fraumeni‐like syndrome mutations in p53 are associated with exonic methylation and splicing regulatory elements

Mutations in codon 133 of p53, which cause the loss of the Delta 133 isoform(s) expression, are very frequent in the Li-Fraumeni (LF) and Li-Fraumeni-like (LFL) syndromes. In sporadic cancers, silent p53 mutations are correlated with exonic splicing enhancers (ESEs) and exonic methylated sites. The present study shows that mutations in splice sites are also very frequent in LF/LFL syndromes, while missense mutations are less common compared to other familial or sporadic cancers (P = 0 in both cases). Furthermore, it is shown that the codons at which LF/LFL germline missense mutations occur, correlate with CpG-containing ESEs (r = 0.181, P = 0.014) which are all methylated in p53. While both silent and LF/LFL missense mutations correlate with SC35 motifs, only the latter are associated with SRp55. On the contrary, only silent mutations in sporadic cancers correlate with SF2/ASF motifs in p53. Moreover, 12.1% of LF/LFL missense mutations involve the formation of potential splice sites of considerable splicing scores. Finally, mutations that are not at, or adjacent to CpGs (+/-1 codon, 34% of all LF/LFL mutated sites), introduce considerable changes of the ESE scores (>1.3 score change). The above data verify that LF/LFL missense mutations probably result also in splicing deregulation, in addition to any changes of the protein function and are mostly associated with alterations of the exonic methylation landscape. Some of the ESEs affected in LF/LFL syndromes are also genetically unstable in sporadic cancers but non-CpG cytosine instability, which is predominantly associated with specific ESEs, is only common in sporadic cancers.

BRCA2: a cause of Li–Fraumeni-like syndrome

In response to a previous article outlining the search for other genes causing Li–Fraumeni syndrome (LFS),1 we have some evidence to suggest that BRCA2 may in some circumstances cause a...

1422 POSTER Educational achievement, marital, smoking status, employment, and insurance in long term survivors of Childhood Hodgkin's Disease

The genetic aetiology of familial aggregations of breast cancer and sarcomas has been elucidated only in part. In this study, 23 unrelated individuals from families with one case of sarcoma and at least one case of breast cancer were screened for mutations in the TP53, BRCA1 and BRCA2 genes. Families were classified according to their conformity to the criteria defining the Li-Fraumeni syndrome (LFS), Li-Fraumeni-like (LFL) syndrome and hereditary breast/ovarian cancer (HBOC). Germline TP53 mutations were identified in three instances (13%), including one LFS and two LFL families, while none of the non-LFS/non-LFL families had a TP53 mutation. Three cases (13%), including one with a TP53 mutation, carried BRCA2 mutations. Of these, two were observed in LFL/HBOC families and the other one in a non-LFS/non-LFL/HBOC family, while none of the non-HBOC families tested positive. These findings suggest that the screening of BRCA2, in addition to TP53, may be appropriate for the molecular characterisation of breast cancer/sarcoma families, with practical implications for counselling and clinical management.