Molecular Analysis of Exons 10, 11 Mutations in BRCA2 Gene In Tehran City Patients with Breast Cancer

Seyedeh Kimia Kiarad; Ali Reza Ahmadi; Lo'bat Geranpayeh; Shahram Sharafi

Authors

Seyedeh Kimia Kiarad Department Of Biology ,Da.C., Islamic Azad University, Damghan, Iran. Author https://orcid.org/0009-0009-1048-6853
Ali Reza Ahmadi Department of Biomedical Sciences, Women Research Center, Alzahra University, Tehran, Iran. Author https://orcid.org/0000-0003-4640-9218
Lo'bat Geranpayeh Associate Professor, Department of Surgery, School of Medicine, Tehran University of Medical Sciences (TUMS), Tehran, Iran. Author https://orcid.org/0000-0001-7100-0129
Shahram Sharafi Assistant Professor, Department of Biology, Da.C., Islamic Azad University, Damghan, Iran. Author https://orcid.org/0000-0001-9726-1220

Keywords:

Breast Cancer, BRCA2, RAD51 , Genetic mutations, Exon, DNA extraction

Abstract

Purpose: This study aimed to investigate genetic alterations in exons 1–5 of the RAD51 gene and to examine their potential association with hereditary breast cancer among women diagnosed with breast cancer in Tehran, Iran.

Methods and Materials: In this molecular study, blood samples were collected from 56 women with invasive or in situ breast cancer in Tehran. Participants were 31–75 years old, with a mean age of 53 years, while controls were selected from a comparable age range with a mean age of 49 years. Genomic DNA was extracted using the saturated-salt method. Target exons were amplified by polymerase chain reaction (PCR) using exon-specific primers, and PCR products were subsequently sequenced by Microsynth, Switzerland. Sequence data were extracted in FASTA format using Chromas Lite and compared with reference sequences using NCBI BLAST. Protein-level analyses were conducted using ExPASy and EBI resources, and predicted secondary and three-dimensional protein structures were evaluated using Phyre2.

Findings: Comparative sequence analysis demonstrated approximately 99% similarity between nucleotide sequences of exon 10 of BRCA2 and reference sequences reported from the United States and the United Kingdom. Exon 11 of BRCA2 showed approximately 97%–99% similarity with sequences reported from Hong Kong, whereas exon 1 of RAD51 demonstrated approximately 98%–99% similarity with reference sequences from the United States. Among the investigated genetic regions, alterations in exon 11 of BRCA2 showed the greatest observed frequency. Phylogenetic comparisons of BRCA2 exons 10 and 11 and RAD51 exon 1 indicated high genetic similarity between the studied Tehran breast-cancer samples and corresponding reference sequences from the United States, United Kingdom, and Hong Kong.

Conclusion: The findings indicate detectable genetic alterations in breast cancer-associated genes among women with breast cancer in Tehran, with particularly notable variation in BRCA2 exon 11. Molecular techniques incorporating PCR and DNA sequencing may contribute to identifying clinically relevant genetic changes and could support earlier molecular assessment of individuals at increased risk of hereditary breast cancer.

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