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Prevalence of the TP53 p.R337H Mutation in Breast Cancer Patients in Brazil  [PDF]
Juliana Giacomazzi, Marcia S. Graudenz, Cynthia A. B. T. Osorio, Patricia Koehler-Santos, Edenir I. Palmero, Marcelo Zagonel-Oliveira, Rodrigo A. D. Michelli, Cristovam Scapulatempo Neto, Gabriela C. Fernandes, Maria Isabel W. S. Achatz, Ghyslaine Martel-Planche, Fernando A. Soares, Maira Caleffi, José Roberto Goldim, Pierre Hainaut, Suzi A. Camey, Patricia Ashton-Prolla
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099893
Abstract: Germline TP53 mutations predispose individuals to multiple cancers and are associated with Li-Fraumeni/Li-Fraumeni-Like Syndromes (LFS/LFL). The founder mutation TP53 p.R337H is detected in 0.3% of the general population in southern Brazil. This mutation is associated with an increased risk of childhood adrenal cortical carcinoma (ACC) but is also common in Brazilian LFS/LFL families. Breast Cancer (BC) is one of the most common cancers diagnosed in TP53 mutation carriers. We have assessed the prevalence of p.R337H in two groups: (1) 59 BC affected women with a familial history (FH) suggestive of hereditary cancer syndrome but no LFS/LFL features; (2) 815 BC affected women unselected for cancer FH, diagnosed with BC at or before age 45 or at age 55 or older. Among group 1 and group 2 patients, 2/59 (3.4%, CI95%: 0.4%–11.7%) and 70/815 (8.6%, CI95%: 6.8%–10.7%), respectively, were p.R337H carriers in the germline. The prevalence of p.R337H was higher in women diagnosed with BC at or before age 45 (12.1%, CI95%: 9.1%–15.8%) than at age 55 or older (5.1%, CI95%: 3.2%–7.7%), p<0.001). The Brazilian founder p.R337H haplotype was detected in all carriers analysed. These results suggest that inheritance of p.R337H may significantly contribute to the high incidence of BC in Brazil, in addition to its recently demonstrated impact on the risk of childhood ACC.
Increased Oxidative Damage in Carriers of the Germline TP53 p.R337H Mutation  [PDF]
Gabriel S. Macedo, Leonardo Lisb?a da Motta, Juliana Giacomazzi, Cristina B. O. Netto, Vanusa Manfredini, Camila S.Vanzin, Carmen Regla Vargas, Pierre Hainaut, Fábio Klamt, Patricia Ashton-Prolla
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047010
Abstract: 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.
The Genomic Landscape of TP53 and p53 Annotated High Grade Ovarian Serous Carcinomas from a Defined Founder Population Associated with Patient Outcome  [PDF]
Paulina M. Wojnarowicz, Kathleen Klein Oros, Michael C. J. Quinn, Suzanna L. Arcand, Karen Gambaro, Jason Madore, Ashley H. Birch, Manon de Ladurantaye, Kurosh Rahimi, Diane M. Provencher, Anne-Marie Mes-Masson, Celia M. T. Greenwood, Patricia N. Tonin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045484
Abstract: High-grade ovarian serous carcinomas (HGSC) are characterized by TP53 mutations and non-random patterns of chromosomal anomalies, where the nature of the TP53 mutation may correlate with clinical outcome. However, the frequency of common somatic genomic events occurring in HGSCs from demographically defined populations has not been explored. Whole genome SNP array, and TP53 mutation, gene and protein expression analyses were assessed in 87 confirmed HGSC samples with clinical correlates from French Canadians, a population exhibiting strong founder effects, and results were compared with independent reports describing similar analyses from unselected populations. TP53 mutations were identified in 91% of HGSCs. Anomalies observed in more than 50% of TP53 mutation-positive HGSCs involved gains of 3q, 8q and 20q, and losses of 4q, 5q, 6q, 8p, 13q, 16q, 17p, 17q, 22q and Xp. Nearly 400 regions of non-overlapping amplification or deletion were identified, where 178 amplifications and 98 deletions involved known genes. The subgroup expressing mutant p53 protein exhibited significantly prolonged overall and disease-free survival as compared with the p53 protein null subgroup. Interestingly, a comparative analysis of genomic landscapes revealed a significant enrichment of gains involving 1q, 8q, and 12p intervals in the subgroup expressing mutant p53 protein as compared with the p53 protein null subgroup. Although the findings show that the frequency of TP53 mutations and the genomic landscapes observed in French Canadian samples were similar to those reported for samples from unselected populations, there were differences in the magnitude of global gains/losses of specific chromosomal arms and in the spectrum of amplifications and deletions involving focal regions in individual samples. The findings from our comparative genomic analyses also support the notion that there may be biological differences between HGSCs that could be related to the nature of the TP53 mutation.
Haplotype analysis of TP53 polymorphisms, Arg72Pro and Ins16, in BRCA1 and BRCA2 mutation carriers of French Canadian descent
Luca Cavallone, Suzanna L Arcand, Christine Maugard, Parviz Ghadirian, Anne-Marie Mes-Masson, Diane Provencher, Patricia N Tonin
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-96
Abstract: The frequencies of the TP53 alleles, genotypes and haplotypes of 157 index breast cancer cases comprised of 42 BRCA1 mutation carriers, 57 BRCA2 mutation carriers, and 58 BRCA mutation-negative cases, where each case was drawn from independently ascertained families were compared. The effect of TP53 variants on the age of diagnosis was also investigated for these groups. The TP53 polymorphisms were also investigated in 112 women of French Canadian descent with no personal history of cancer.The BRCA mutation-positive groups had the highest frequency of homozygous carriers of the 72Pro allele compared with mutation-negative group. The TP53 polymorphisms exhibited linkage disequilibrium (p < 0.001), where the 72Arg and Ins16minus alleles occurred in strong disequilibrium. The highest frequency of carriers of Ins16minus-72Arg haplotype occurred in the BRCA mutation-negative groups. The BRCA1 mutation carriers homozygous for the 72Pro allele had the youngest ages of diagnosis of breast cancer. However none of these observations were statistically significant. In contrast, the BRCA2 mutation carriers homozygous for the 72Pro allele had a significantly older age of diagnosis of breast cancer (p = 0.018). Moreover, in this group, the mean age of diagnosis of breast cancer in carriers of the Ins16minus-72Arg haplotype was significantly younger than that of the individuals who did not this carry this haplotype (p = 0.009).We observed no significant association of breast cancer risk with TP53 genetic variants based on BRCA1/2 mutation carrier status. Although the small sample size did not permit analysis of all possible haplotypes, we observed that BRCA2 mutation carriers harboring the Ins16minus-72Arg haplotype had a significantly younger mean age of diagnosis of breast cancer. These observations suggest that investigations in a larger French Canadian sample are warranted to further elucidate the effects of TP53 variants on age of diagnosis of breast cancer among BRCA1 and BR
TP53 mutations in ovarian carcinomas from sporadic cases and carriers of two distinct BRCA1 founder mutations; relation to age at diagnosis and survival
Pedro Kringen, Yun Wang, Vanessa Dumeaux, Jahn M Nesland, Gunnar Kristensen, Anne-Lise Borresen-Dale, Anne Dorum
BMC Cancer , 2005, DOI: 10.1186/1471-2407-5-134
Abstract: DNA was extracted from paraffin embedded formalin fixed tissues for the familial cases, and from fresh frozen specimen from the sporadic cases. All cases were treated at our hospital according to protocol. Mutation analyses of exon 2 – 11 were performed using TTGE, followed by sequencing.Survival rates for BRCA1-familial cases with TP53 mutations were not significantly lower than for familial cases without TP53 mutations (p = 0.25, RR = 1.64, 95% CI [0.71–3.78]). Median age at diagnosis for sporadic (59 years) and familial (49 years) cases differed significantly (p < 0.001) with or without TP53 mutations. Age at diagnosis between the two types of familial carriers were not significantly different, with median age of 47 for 1675delA and 52.5 for 1135insA carriers (p = 0.245). For cases ≥50 years at diagnosis, a trend toward longer survival for sporadic over familial cases was observed (p = 0.08). The opposite trend was observed for cases <50 years at diagnosis.There do not seem to be a protective advantage for familial BRCA1 carriers without TP53 mutations over familial cases with TP53 mutations. However, there seem to be a trend towards initial advantage in survival for familial cases compared to sporadic cases diagnosed before the age of 50 both with and without TP53 mutations. However, this trend diminishes over time and for cases diagnosed ≥50 years the sporadic cases show a trend towards an advantage in survival over familial cases. Although this data set is small, if confirmed, this may be a link in the evidence that the differences in ovarian cancer survival reported, are not due to the type of BRCA1 mutation, but may be secondary to genetic factors shared. This may have clinical implications for follow-up such as prophylactic surgery within carriers of the two most frequent Norwegian BRCA1 founder mutations.Ovarian cancer is one of the leading causes of cancer-related death in women today. It is the 4th most common cancer in women in Norway and accounts for 5
Number of rare germline CNVs and TP53 mutation types  [cached]
Silva Amanda G,Achatz Isabel Maria W,Krepischi Ana CV,Pearson Peter L
Orphanet Journal of Rare Diseases , 2012, DOI: 10.1186/1750-1172-7-101
Abstract: Background The Li-Fraumeni syndrome (LFS), an inherited rare cancer predisposition syndrome characterized by a variety of early-onset tumors, is caused by different highly penetrant germline mutations in the TP53 gene; each separate mutation has dissimilar functional and phenotypic effects, which partially clarifies the reported heterogeneity between LFS families. Increases in copy number variation (CNV) have been reported in TP53 mutated individuals, and are also postulated to contribute to LFS phenotypic variability. The Brazilian p.R337H TP53 mutation has particular functional and regulatory properties that differ from most other common LFS TP53 mutations, by conferring a strikingly milder phenotype. Methods We compared the CNV profiles of controls, and LFS individuals carrying either p.R337H or DNA binding domain (DBD) TP53 mutations by high resolution array-CGH. Results Although we did not find any significant difference in the frequency of CNVs between LFS patients and controls, our data indicated an increased proportion of rare CNVs per genome in patients carrying DBD mutations compared to both controls (p=0.0002***) and p.R337H (0.0156*) mutants. Conclusions The larger accumulation of rare CNVs in DBD mutants may contribute to the reported anticipation and severity of the syndrome; likewise the fact that p.R337H individuals do not present the same magnitude of rare CNV accumulation may also explain the maintenance of this mutation at relatively high frequency in some populations.
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
Daphne SC Lee, Sook-Yee Yoon, Lai Looi, Peter Kang, In Kang, Kavitta Sivanandan, Hany Ariffin, Meow Thong, Kin Chin, Nur Mohd Taib, Cheng-Har Yip, Soo-Hwang Teo
Breast Cancer Research , 2012, DOI: 10.1186/bcr3172
Abstract: A 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.We 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.Our 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.To date, germline mutations in at least 10 genes linked to DNA repair have been shown to be associa
Haplotype Analysis Reveals a Possible Founder Effect of RET Mutation R114H for Hirschsprung's Disease in the Chinese Population  [PDF]
Belinda K. Cornes,Clara S. Tang,Thomas Y. Y. Leon,Kenneth J. W. S. Hui,Man-Ting So,Xiaoping Miao,Stacey S. Cherny,Pak C. Sham,Paul K. H. Tam,Maria-Merce Garcia-Barcelo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010918
Abstract: Hirschsprung's disease (HSCR) is a congenital disorder associated with the lack of intramural ganglion cells in the myenteric and sub-mucosal plexuses along varying segments of the gastrointestinal tract. The RET gene is the major gene implicated in this gastrointestinal disease. A highly recurrent mutation in RET (RETR114H) has recently been identified in ~6–7% of the Chinese HSCR patients which, to date, has not been found in Caucasian patients or controls nor in Chinese controls. Due to the high frequency of RETR114H in this population, we sought to investigate whether this mutation may be a founder HSCR mutation in the Chinese population.
Spinocerebellar ataxia type 17: Report of a family with reduced penetrance of an unstable Gln49 TBP allele, haplotype analysis supporting a founder effect for unstable alleles and comparative analysis of SCA17 genotypes
Christine Zühlke, Andreas Dalski, Eberhard Schwinger, Ulrich Finckh
BMC Medical Genetics , 2005, DOI: 10.1186/1471-2350-6-27
Abstract: Here, we report the first pedigree with a Gln49 allele that is a) not interrupted, b) unstable upon transmission, and c) associated with reduced penetrance or very late age of onset. The 76-year-old father of two SCA17 patients carries the Gln49 TBP allele but presents without obvious neurological symptoms. His children with Gln53 and Gln52 developed ataxia at the age of 41 and 50. Haplotype analysis of this and a second family both with uninterrupted expanded and unstable pathological SCA17 alleles revealed a common core genotype not present in the interrupted expansion of an unrelated SCA17 patient. Review of the literature did not present instability in SCA17 families with expanded alleles interrupted by the CAA CAG CAA element.The presence of a Gln49 SCA17 allele in an asymptomatic 76-year-old male reams the discussion of reduced penetrance and genotypes producing very late disease onset. In SCA17, uninterrupted expanded alleles of TBP are associated with repeat instability and a common founder haplotype. This suggests for uninterrupted expanded alleles a mutation mechanism and some clinical genetic features distinct from those alleles interrupted by a CAA CAG CAA element.The spinocerebellar ataxias (SCAs), a group of autosomal dominantly inherited human disorders with mainly adult age of onset, are caused by progressive neurodegeneration and significant cerebellar dysfunction, but also involve other regions of the central or peripheral nervous system. Clinically and even histopathologically the differentiation between SCA subtypes may be rather difficult. Genetically, for 25 types causative mutations in various genes are known or defined by linkage to distinct chromosomal regions. For seven SCAs expanded CAG trinucleotide repeats have been discovered [1]. This kind of mutation seems to be specific for the human species.SCA17 [OMIM: 607136], a rare type of SCA with a variety of clinical features, is caused by an expanded CAG repeat in TBP, the gene of the TATA b
Mechanism of origin in two cases of chimerism  [PDF]
Antonella Minelli, Andrea Guala, Alberto Groppo, Gabriella Restagno, Roberto Lala, Silvia Einaudi, Mariaelena Repici, Emilio Merlini, Luca Sbaiz, Valentina Asnaghi, Ana Graciela Lopez, Paola Angellotti, Silvia Cristina, Cesare Danesino
Open Journal of Pediatrics (OJPed) , 2011, DOI: 10.4236/ojped.2011.14019
Abstract: Chimerism is defined as the presence in a subject of more than one stable and genetically distinct cell line; cases reported so far include both patients with ambiguous genitalia and healthy subjects. The biological mechanisms, which may give origin to chimeras, are complex, and can be understood by analyzing DNA samples of the patients and their parents using molecular techniques. The objective of this study is to identify the mechanism of origin for the 2 cases we report. The first patient is a phenotipically normal girl with normal (external and internal) genitalia; the second patient had ambiguous genitalia and underwent surgery. DNA was purified from blood samples and, limited to Patient 1, from a sample of biliary cyst. Short tandem repeat polymorphisms were analyzed in order to identify the relative parental contribution to the patients. Molecular analyses carried out on the first patient are not fully informative because of two possible explanations (i.e. parthenogenetic and andrognetic chimera), while in the second case the presence of four alleles at some markers allowed us to identify a tetragametic chimera originnated from the fusion of two distinct embryos. Studies carried on one single tissue may not always be conclusive as they do not allow the precise identification of the mechanism of origin. In these cases, studies on more tissues are strongly suggested.
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