MED12 mutant fibroids had 4.4 times higher odds of shrinking in response to ulipristal acetate treatment as compared to HMGA2 driven fibroids (95% confidence interval 1.37–13.9; P = 0.013), and in a multivariate analysis molecular subclassification was an independent predictive factor. This evidence concerns the gene HMGA2 and leiomyoma.