The reason for this, along with powerful hormonal effects occurring during pregnancy in the mother’s body, may be a factor of the immunization of the maternal organism with embryonic proteins, among which there are many antigens specifically expressed on the surface of leiomyoma cells, in particular: Satb2, Nrg1, PCP4, CHRDL2, MFAP2, HMGA2, PLAG1, PAPPA2, MB21D2, ADAM12, MMP11, and MMP16. This evidence concerns the gene MMP11 and leiomyoma.