Racial diversity and uterine leiomyoma

Uterine leiomyoma (ULM) represents the most frequent indication for hysterectomy in the USA. It costs the USA annually $5.9-34.4 billion in direct and indirect costs. The incidences of ULM in black races are higher compared to white races. Both estrogen and progesterone have a role in initiating and promoting ULM. Several important genetic variations have been connected to the higher prevalence of ULM in black women. The steady increase in serum estradiol and progesterone concentration among premenopausal women may depend on the number of CYP17 gene alleles that a woman carries. Catechol-O-methyltransferase (COMT) gene, which has an important role in the inactivation of catechol estrogens, may indirectly modulate the biological effects of estrogen and thus play an etiological role in leiomyoma formation. High-density tissue microarray has been used to identify the ethnic differences in the expression of selected gene products in ULM versus adjacent normal myometrium and showed a clear down-regulation of retinoic acid receptors (RAR-a and RXR-a) in ULM of Black women in comparison with their up-regulation in other ethnic groups. Finally, this chapter will try to discuss whether the function or the expression of steroid receptors is contributing to the racial differences in the incidence of ULM.