ACE and polycystic ovary syndrome: Two possibilities may account for this observation: 1) the concentration of T is not associated with ACE; 2) ACE is not the key factor that influences the concentration of T. However, in the PCOS patients the total T concentrations between the I/D and I/I genotypes were different, which cannot be explained if ACE is not associated with the concentration of T. The most probable reason may be that the ACE I/D polymorphisms is only one of the co-factors that affects the etiopathogenisis of PCOS by interacting with other factors.