N Hadiji-Abbes1, F Trifa1, M Choura1, A Khabir2, T Sellami-Boudawara2, M Frikha2, J Daoud2, R Mokdad-Gargouri3. 1. Center of Biotechnology of Sfax, University of Sfax, BP K 3018, Sfax, Tunisia. 2. Departement of Anatomoapathology, Oncology and Radiotherapy of Habib Bourguiba Hospital, Sfax, Tunisia. 3. Center of Biotechnology of Sfax, University of Sfax, BP K 3018, Sfax, Tunisia. Electronic address: raja.gargouri@cbs.rnrt.tn.
Abstract
BACKGROUND: Breast cancer is increasing among young women in Tunisia. Germline mutations in the BRCA1/2 genes are associated with a high risk for breast cancer development. However, the true contribution of BRCA1/2 mutation in sporadic breast cancer is not well documented. Our aim is to identify the BRCA2 mutation spectrum in Tunisian young women with breast cancer. METHODS: Screening the BRCA2 gene was performed using DHPLC, DNA sequencing and PCR-RFLP. RESULTS: We identified, in a woman diagnosed with early onset breast cancer, and without family history, a novel in frame deletion 5456delGTAGCA in the exon 11 of the BRCA2 gene which causes a loss of two residues Ser1743-Ser1744. The absence of this deletion in the patients' parents suggests that it is a de novo variant. Furthermore, we screened 108 sporadic cases, 50 familial cases, and 60 controls for the identified del6bp using PCR-RFLP. None of them carried this deletion suggesting that this variant is not a benign polymorphism and probably rare in our population. With regards to the position of the Ser1743-1744 in the BRCT domain, sequence alignment revealed that the Ser1743 is conserved among several species, which may reflect its importance in the BRCA2 function. A modeling of the wild-type and mutated BRC5-BRC6 domain revealed that the deletion of the 2 Serine residues might affect the structure of this BRCA2 domain. CONCLUSIONS: A novel in frame deletion 5456del6bp in BRCA2 gene was identified in an early onset woman with breast cancer and without family history.
BACKGROUND:Breast cancer is increasing among young women in Tunisia. Germline mutations in the BRCA1/2 genes are associated with a high risk for breast cancer development. However, the true contribution of BRCA1/2 mutation in sporadic breast cancer is not well documented. Our aim is to identify the BRCA2 mutation spectrum in Tunisian young women with breast cancer. METHODS: Screening the BRCA2 gene was performed using DHPLC, DNA sequencing and PCR-RFLP. RESULTS: We identified, in a woman diagnosed with early onset breast cancer, and without family history, a novel in frame deletion 5456delGTAGCA in the exon 11 of the BRCA2 gene which causes a loss of two residues Ser1743-Ser1744. The absence of this deletion in the patients' parents suggests that it is a de novo variant. Furthermore, we screened 108 sporadic cases, 50 familial cases, and 60 controls for the identified del6bp using PCR-RFLP. None of them carried this deletion suggesting that this variant is not a benign polymorphism and probably rare in our population. With regards to the position of the Ser1743-1744 in the BRCT domain, sequence alignment revealed that the Ser1743 is conserved among several species, which may reflect its importance in the BRCA2 function. A modeling of the wild-type and mutated BRC5-BRC6 domain revealed that the deletion of the 2 Serine residues might affect the structure of this BRCA2 domain. CONCLUSIONS: A novel in frame deletion 5456del6bp in BRCA2 gene was identified in an early onset woman with breast cancer and without family history.