RESUMEN
The Müllerian inhibiting factor (MIF) is responsible for regression of Müllerian ducts during male sexual differentiation. Mutations in MIF or its type II receptor lead to persistence of the uterus and Fallopian tubes in male children--i.e., persistent Müllerian duct syndrome (PMDS). Both are rare autosomal recessive disorders. We report a 7-month-old male infant who underwent inguinal herniorrhaphy. Remnants of vas deferens and gonads with macroscopic characteristics of ovaries, along with Fallopian tubes and a rudimentary uterus, were found. Karyotype confirmed male sex. Molecular genetics revealed the most frequent MIF type II receptor gene mutation--27 bp deletion. Investigation of the older brother presenting bilateral cryptorchidism at 7 years of age led to similar clinical findings and the same mutation. We report here an MIF type II receptor mutation in two brothers, with the particularity that the surgical findings in the younger son initiated the diagnostic process in both children.