The oestrogen receptor codon 10 polymorphism detected in breast cancer is also present in non-malignant cells

The effect of oestrogens on oestrogen-receptive organs and cells is mediate d via intracellular receptors (ER alpha and ER beta). Oestrogen receptor ge ne polymorphisms in the region encoding the N-terminal portion of the prote in are reportedly associated with pathological conditions including breast cancer, hypertension, spontaneous abortion and coronary heart disease. A si lent mutation in codon 10 of exon 1, detected in ER-negative and ER-positiv e human breast cancer cell lines, in breast tumors and blood DNA from breas t cancer patients, has been recognized as a polymorphic site. In this study we examined. by denaturing gradient-gel electrophoresis and DNA sequence a nalysis, the possible presence of a codon 10 polymorphic site in normal oes trogen target organs and cells such as the uterus (myometrium and endometri um), in the placenta and peripheral blood mononuclear cells and in a benign uterus tumour (leiomyoma). We have detected ER codon 10 polymorphism in th ese samples and, have compared them to those observed in breast cancer samp les. All tissues and cells studied were homozygous for the wild-type gene, and were heterozygous as well as homozygous for the codon-10-variant type. These results indicate that the presence of the codon-10-variant type is no t a characteristic of breast cancer. Out current findings suggest that furt her investigations are warranted to elucidate the possible linkage of ER co don 10 polymorphism to physiological and pathological conditions.