Trinucleotide Repeat Polymorphism in Transforming Growth Factor Beta Receptor Type 1 Gene and Risk of Breast Cancer

Background: Transforming growth factor beta receptor type 1 (TGFBR1) is a serine–threonine protein kinase which mediates the growth-inhibitory signals of TGFB1 through a complex with TGFBR2. Numerous epidemiological studies have evaluated the association of TGFBR1 polymorphisms and the risk of cancer. The purpose of this study was to investigate the tri-nucleotide polymorphism (GCG) in exon 1 of TGFBR1 gene and its association with risk of breast cancer in women. Methods: This study was conducted on 200 women with breast cancer and 200 healthy women in Isfahan, Iran. After DNA extraction from peripheral blood samples, desired sequence was amplified by polymerase chain reaction (PCR). Finally, GCG repeat polymorphism was determined by polyacrylamide gel electrophoresis and direct sequencing. Findings: The TGFBR1 gene allele distribution in studied women varied between 6 and 9. The most common allele in both controls and cases was (GCG)9. The frequencies of (GCG)6 allele or homozygote of (GCG)6 in patients were significantly lower than controls. Conclusion: Contrary to previous reports, our findings demonstrate that women who carry (GCG)6 allele of TGFBR1 gene are at lower risk of developing breast cancer. Our results suggest a protective role of this allele against breast cancer.