MED12 and leiomyoma: Recent single-cell and spatial transcriptomic studies have further refined this landscape, showing that leiomyomas are composed of heterogeneous smooth muscle and fibroblast populations, with subtype-specific distributions—MED12-mutant fibroids containing balanced SMC and fibroblast proportions, while HMGA2-rearranged fibroids are strongly SMC-dominant [79,80].