Sequence Variants of BRCA1 and BRCA2 Genes in Four Iranian Families with Breast and Ovarian Cancer

Abstract

Background: BRCA1 and BRCA2 genes have been recognized to be responsible for 20-30% of hereditary breast can­cers and approximately 50% of familial breast and ovarian cancers. Therefore, the demand for BRCA1 and BRCA2 muta­tion screening is rapidly increasing as their identification will affect medical management of people at increased risk. Because of high costs involved in analysis of BRCA1 and 2 genes, contribution of different mutation types in BRCA1 and 2 and not knowing who should be tested has hampered wide spread use of molecular testing of high -risk fami­lies. There is a need to identify the genes and types of mutations involved in breast or ovarian cancers at different age of onsets and polymorphism and polymorphic variations in our population.
Methods: Twenty-seven patients with either early onset breast cancer (at age≤ 35 years) or a personal and/or family his­tory of breast or ovarian cancer and 50 control subjects participated in this study. After collecting blood samples and extract­ing DNA, BRCA1 and BRCA2 genes were fully sequenced.
Results: Thirteen missense substitutions in BRCA1 and BRCA2 (9 and 4, respectively) were revealed. Two nucleotide substitu­tions were novel (Gly1140Ser in BRCA1 and Glu1391Gly in BRCA2). The Glu1038Pro and Gly1140Ser were found in large series of breast and ovarian cancer and matched controls.
Conclusion: Some nucleotide substitutions were seen only in single families and other in several. In other cases, muta­tions were seen in both BRCA1 and BRCA2 genes. Clinical significance of these mutations was evaluated comparing with normal controls.