LOSS OF HETEROZYGOSITY OF THE ESTROGEN-RECEPTOR GENE IN BREAST-CANCER

DNA from 67 primary breast carcinoma biopsies has been examined for lo ss of heterozygosity (LOH) using the microsatellite (TA)(n) repeat mar ker positioned 1 kb upstream of the oestrogen receptor (ER) gene. Fort y-seven (70.1%) of the cases were informative; nine of these (19.1%) w ere positive for LOH. In three of the nine cases, there was total loss , and in the other six cases there was a marked reduction in the inten sity of signal from one allele. LOH correlated weakly with histologica l grade and age, but not with ER status. This result suggests that LOH of the ER gene does not have an important role in the lack of ER func tion in breast cancer tissues.