Thus we conducted the present study to further explore the molecular mechanisms responsible for the observed volume reduction in leiomyoma, in response to mifepristone treatment, with the aim to identify potential molecular markers that could be used for screening and identification of leiomyomas suitable for pharmacological management Our results demonstrates that the response to mifepristone with regard to leiomyoma volume reduction correlated to expression of glutathione-s transferase mu 1 (GSTM1). This evidence concerns the gene GSTM1 and leiomyoma.