Transforming growth factor ? receptor I polyalanine repeat polymorphism does not increase ovarian cancer risk
Objectives It has been suggested that the 6A allele of the type I TGF? receptor (TGF?R1) polyalanine repeat tract polymorphism may increase susceptibility to various types of cancer including ovarian cancer. Methods The TGF?R1 polyalanine polymorphism was genotyped in 588 ovarian cancer cases and 614 controls from a population-based case-control study in North Carolina. Results Significant racial differences in the frequency of the 6A allele were observed between Caucasian (10.7%) and African-American (2.4%) controls (P < 0.001). One or two copies of the 6A allele of the TGF?R1 polyalanine polymorphism was carried by 18% of all controls and 19% of cases, and there was no association with ovarian cancer risk (OR = 1.07, 95% CI 0.80–1.44). The odds ratio for 6A homozygotes was 1.81 (95% CI 0.655.06), but these comprised only 0.98% of controls and 1.70% of cases. Conclusions The 6A allele of the TGF?R1 polyalanine polymorphism does not appear to increase ovarian cancer risk. Larger studies would be needed to exclude the possibility that the small fraction of individuals who are 6A homozygotes have an increased risk of ovarian or other cancers.