CYP19A1 and uterine corpus leiomyoma: Overexpression of estrogen receptor (ER) alpha genotype and aromatase, which has been found to correlate with incidence and size of uterine fibroids, is particularly pronounced in Afro-American women [9, 10] and may explain why African American women are at three to five times greater risk for fibroids than white women and Negros 3–9 times than Caucasians [10].