SEQUENCE VARIANTS OF THE ESTROGEN-RECEPTOR (ER) GENE FOUND IN BREAST-CANCER PATIENTS WITH ER NEGATIVE AND PROGESTERONE-RECEPTOR POSITIVE TUMORS

Thirteen pairs of tumor and blood DNAs from breast cancer patients wit h estrogen receptor (ER) negative and progesterone receptor (PgR) posi tive tumors were screened for mutation analysis using SSCP method. Alt hough neither germline nor somatic mutation of the ER gene in this ser ies was detected, we found two types of sequence variants in exon 1 an d exon 4, indicating two silent mutations in codon 10 (TCT to TCC) and codon 325 (CCC to CCG), respectively. These variants were recognized as polymorphic sites. Although the frequency of these polymorphic site s was not correlated with hormone receptor status, the variant in codo n 325 tended to be seen more frequently in breast cancer patients than in non-cancer control cases (P = 0.057).