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 with estrogen receptor (ER) negative and progesterone receptor (PgR) positive tumors were screened for mutation analysis using SSCP method. Although neither germline nor somatic mutation of the ER gene in this series was detected, we found two types of sequence variants in exon 1 and 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 sites was not correlated with hormone receptor status, the variant in codon 325 tended to be seen more frequently in breast cancer patients than in non-cancer control cases (P = 0.057).