Recently, molecular forms of PSA (α1-antichymotripsin-bound PSA and free PSA) have been investigated in the sera of women with benign and malignant breast diseases and it has been reported that existence of free PSA as the major molecular form may be of diagnostic importance in female breast cancer (Borchert et al, 1997; Black et al, 2000). The gene discussed is KLK3; the disease is breast carcinoma.