Whereas ER and PR were ubiquitously expressed in the epithelial as well as stromal cells of the endometrium, the proliferative capacity, measured by Ki67 expression, was almost absent in the epithelium and stroma of MRKH patients (Fig. 1D), as reported previously (Rall et al., 2013). The gene discussed is ESR1; the disease is Mayer-Rokitansky-Kuster-Hauser syndrome.