Breast cancer, Cowden disease and PTEN-MATCHS syndrome

Association of Single-Nucleotide Polymorphisms in Monoubiquitinated FANCD2-DNA Damage Repair Pathway Genes With Breast Cancer in the Chinese Population

Objective:

The aim of the study was to estimate breast cancer risk conferred by individual single-nucleotide polymorphisms of breast cancer susceptibility genes.

Methods:

We analyzed the 48 tagging single-nucleotide polymorphisms of 8 breast cancer susceptibility genes involved in the monoubiquitinated FANCD2–DNA damage repair pathway in 734 Chinese women with breast cancer and 672 age-matched healthy controls.

Results:

Forty-five tagging single-nucleotide polymorphisms were successfully genotyped by SNPscan, and the call rates for each tagging single-nucleotide polymorphisms were above 98.9%. We found that 13 tagging single-nucleotide polymorphisms of 5 genes (Parter and localizer of Breast cancer gene2 (PALB2), Tumour protein 53 (TP53), Nijmegen breakage syndrome 1, Phosphatase and tensin homolog deleted from chromosome 10 (PTEN), and Breast cancer gene 1 (BRCA1-interacting protein 1)) were significantly associated with breast cancer risk. A total of 5 tagging single-nucleotide polymorphisms (rs2299941 of PTEN, rs2735385, rs6999227, rs1805812, and rs1061302 of Nijmegen breakage syndrome 1) were tightly associated with breast cancer risk in sporadic cases, and 5 other tagging single-nucleotide polymorphisms (rs1042522 of TP53, rs2735343 of PTEN, rs7220719, rs16945628, and rs11871753 of BRCA1-interacting protein 1) were tightly associated with breast cancer risk in familial and early-onset cases.

Conclusions:

Some of the tagging single-nucleotide polymorphisms of 5 genes (PALB2, TP53, Nijmegen breakage syndrome 1, PTEN, and BRCA1-interacting protein 1) involved in the monoubiquitinated FANCD2–DNA damage repair pathway were significantly associated with breast cancer risk.

Hereditary breast cancer associated with Cowden syndrome-related PTEN mutation with Lhermitte-Duclos disease

BACKGROUND

Cowden syndrome is characterized by multiple hamartomas in various tissues, including the skin, brain, breast, thyroid, mucous membrane, and gastrointestinal tract, and is reported to increase the risk of malignant disease.

CASE PRESENTATION

We describe the case of a 52-year-old woman in whom a tumor was diagnosed in the left cerebellar hemisphere and treated by surgical resection. Phosphatase and tensin homolog (PTEN) mutation in exon 8 insertion was found in the brain tumor tissue and leukocytes. This finding supported the diagnosis of Cowden syndrome. She consequently developed endometrial cancer and underwent abdominal total hysterectomy with bilateral salpingo-oophorectomy. Four years later, hormone receptor-positive breast cancer was found in the right breast, and breast-conserving surgery with radiation therapy and sentinel lymph node biopsy was performed.

CONCLUSIONS

Herein, we describe a patient who was diagnosed as having familial breast cancer associated with PTEN mutation-related Cowden syndrome. We also reviewed reports of this syndrome in the literature for disease appraisal.

Oral presentation of 10 patients with Cowden syndrome

Cowden syndrome (CS) is an autosomal dominant genodermatosis that frequently affects several tissues with hamartomatous growth. The oral cavity is quite commonly involved with papillomatous lesions, which can be crucial to early diagnosis of this disease. In this series, 10 patients with a great diversity of manifestations associated with CS are presented, in whom oral papillomatosis was a constant and relevant finding to establish the diagnosis of CS. The role of the dentist in recognizing the oral lesions, the other diagnostic criteria, the risk for the development of malignancies, and the importance of lifetime follow-up are discussed.

[Cowden syndrome]

INTRODUCTION

Cowden syndrome is rare; oral symptoms are not always diagnosed. This case of Cowden syndrome was revealed by gingival hypertrophy.

OBSERVATION

A 21-year-old female patient consulted for gingival hypertrophy and multiple papules in the mouth. She had a history of thyroid lobectomy due to a goiter. The gingival papillomatosis and the goiter suggested a Cowden syndrome. The diagnosis was confirmed clinically by facial skin papules.

DISCUSSION

Cutaneous and oral lesions are usually the first symptoms of the syndrome. Diffuse gingival papillomatosis may suggest a Cowden syndrome and should lead to screen for associated symptoms. A high-risk diagnosis of breast and thyroid cancer is associated to Cowden syndrome and the patient should have a yearly follow-up.

Mutational analysis of FANCL, FANCM and the recently identified FANCI suggests that among the 13 known Fanconi Anemia genes, only FANCD1/BRCA2 plays a major role in high-risk breast cancer predisposition

Fanconi Anemia (FA) is a rare recessive syndrome characterized by cellular hypersensitivity to DNA-cross-linking agents. To date, 13 FA complementation groups have been described and all 13 genes associated to each of these groups have been currently identified. Three of the known FA genes are also high-risk (FANCD1/BRCA2) or moderate-risk (FANCN/PALB2 and FANCJ/BRIP1) breast cancer susceptibility genes, which makes all members of the FA pathway particularly attractive breast cancer candidate genes. Most FA genes have been screened for mutations in breast cancer families negative for BRCA1/2 mutations but the role of FANCL, FANCM and the recently identified FANCI has not been evaluated to date. This fact and novel data sustaining greater functional relevance of the three genes within the FA pathway prompted us to scrutinize all coding sequences and splicing sites of FANCI, FANCL and FANCM in 95 BRCA1/2-negative index cases from Spanish high-risk breast cancer families. We identified 68 sequence variants of which 24 were coding and 44 non-coding. Six exonic and 26 non-coding variants had not been described previously. None of the coding changes caused clearly pathogenic changes and computational analysis of all non-described intronic variants did not revealed major impact in splicing. With the present study, all known FA genes have been evaluated within the context of breast cancer high-risk predisposition. Our results rule out a major role of FANCI, FANCL and FANCM in familial breast cancer susceptibility, suggesting that among the 13 known FA genes, only FANCD1/BRCA2 plays a major role in high-risk breast cancer predisposition.

Mutational analysis of the breast cancer susceptibility gene BRIP1 /BACH1/FANCJ in high-risk non-BRCA1/BRCA2 breast cancer families

The BRIP1 gene encodes a helicase interacting with BRCA1, which contributes to BRCA1-associated DNA repair function. Germ-line BRIP1 mutations affecting the helicase domain activity have been identified in early onset breast cancer patients. In addition, BRIP1 was recently identified as deficient in Fanconi anemia (FA) complementation group J. Given the growing evidence now linking BRCA1, BRCA2, and the FA pathway, as well as the involvement of FA proteins (BRCA2/FANCD1 and PALB2/FANCN) in breast cancer susceptibility, we sought to evaluate the contribution of FANCJ gene alterations regarding breast cancer susceptibility among our cohort of 96 breast cancer individuals from high-risk non-BRCA1/2 French Canadian families. No deleterious mutation, exon deletion, or retention of intronic portions could be identified. However, extensive analysis of the promoter and whole exonic and flanking intronic regions of FANCJ led to the identification of 42 variants, including 22 novel variants not previously reported, four of which were located in the promoter region. Transcription factors analysis revealed a potential involvement of FANCJ promoter variants in regulation of FANCJ expression, and reporter gene assays were performed. The allelic frequency was assessed in a cohort of 73 unaffected French Canadian individuals, and haplotype analysis and tagging single nucleotide polymorphism (SNP) identification were also performed. Although our study unlikely involves FANCJ as a high-risk predisposition gene in non-BRCA1/2 high-risk French Canadian families, the possible association of FANCJ missense variants with phenotypes associated with FA, such as childhood cancer, cannot be excluded.

Genetic susceptibility to breast cancer

Deleterious mutations in two breast and ovarian cancer susceptibility genes, BRCA1 and BRCA2 have been identified in breast and ovarian cancer families. Women with a BRCA1 or BRCA2 mutation are candidates for additional risk reduction measures such as intensive screening, prophylactic surgery or chemoprevention. Additional susceptibility genes have been identified, including PTEN, ATM, TP53, CHEK2, CASP8, PBRL and BRIP1. Yet, many women with a personal or family history suggestive of a hereditary susceptibility to breast cancer undergo genetic testing and no significant genetic alteration is found. Thus, there are other susceptibility genes that have not been identified, and it is likely that the remaining familial contribution to breast cancer will be explained by the presence of multiple low penetrance alleles that coexist to confer high penetrance risks (a polygenic model). The American Cancer Society has identified cancer prevention as a key component of cancer management and there is interest in developing individualized cancer prevention focused on identifying high risk individuals who are most likely to benefit from more aggressive risk reduction measures. Breast cancer risk assessment and genetic counseling are currently provided by genetic counselors, oncology nurse specialist, geneticists, medical and surgical oncologists, gynecologists and other health care professionals, often working within a multidisciplinary clinical setting. Current methods for risk assessment and predictive genetic testing have limitations and improvements in molecular testing and risk assessment tools is necessary to maximize individual breast cancer risk assessment and to fulfill the promise of cancer prevention.

Germline mutations in the breast cancer susceptibility gene PTEN are rare in high-risk non-BRCA1/2 French Canadian breast cancer families

Cowden syndrome is a disease associated with an increase in breast cancer susceptibility. Alleles in PTEN and other breast cancer susceptibility genes would be responsible for approximately 25% of the familial component of breast cancer risk, BRCA1 and BRCA2 being the two major genes responsible for this inherited risk. In order to evaluate the proportion of high-risk French Canadian non-BRCA1/BRCA2 breast/ovarian cancer families potentially harboring a PTEN germline mutation, the whole coding and flanking intronic sequences were analyzed in a series of 98 breast cancer cases. Although no germline mutation has been identified in the coding region, our study led to the identification of four intronic variants. Further investigations were performed to analyze the effect of these variants, alone and/or in combination, on splicing and PTEN protein levels. Despite suggestive evidence emerging from in silico analyses, the presence of these intronic variants do not seem to alter RNA splicing or PTEN protein levels. In addition, as loss of PTEN or part of it has been reported, Western blot analysis has also been performed. No major deletion could be identified in our cohort. Therefore, assuming a Poisson distribution for the frequency of deleterious mutation in our cohort, if the frequency of such deleterious mutation was 2%, we would have had a 90% or greater chance of observing at least one such mutation. These results suggest that PTEN germline mutations are rare and are unlikely to account for a significant proportion of familial breast cancer cases in the French Canadian population.