Ethnic variations in uterine leiomyoma biology are not caused by differences in myometrial estrogen receptor alpha levels

Uterine leiomyomas develop in women of reproductive age and regress after menopause, suggesting that they grow in a steroid hormone-dependent fashion. Furthermore, it is widely accepted that symptomatic uterine leiomyomas occur at a twofold to threefold higher frequency in black women than in white women. The present study was designed to investigate a possible physiologic role of racial differences in the myometrial estrogen receptor alpha in this phenomenon. We compared the expression of the estrogen receptor and progesterone receptor in myometrium by ligand-binding assay and the estrogen receptor alpha by real-time polymerase chain reaction in women from different ethnic backgrounds who have uterine leiomyoma. Estrogen receptor and progesterone receptor concentrations and estrogen receptor alpha transcription levels were not statistically different between ethnic backgrounds. Neither on a transcriptional nor on a protein level were there statistically relevant differences in steroid hormone receptor levels. A causative role for these receptors in the ethnic variation of leiomyoma biology seems unlikely