Fetomaternal alloimmunization with antenatal glomerulopathies (FMAIG) is a recently described alloimmune disorder, which results from maternal antibodies that cross the placenta, bind to fetal glomerular podocytes, and mediate renal disease. The pathogenic antibodies are directed against neutral endopeptidase (NEP). The infant's mother is NEP-deficient and thus she becomes immunized during pregnancy against NEP expressed by placental cells. Because future pregnancies in NEP-immunized mothers are at high risk for the fetus, detection of anti-NEP antibodies in pregnant mothers and antigen-driven therapies including induction of mucosal tolerance, are urgently needed. This ideally requires identification of the pathogenic epitopes born by the antigen. We have recently characterized two linear B cell epitopes on the NEP that are specifically recognized by the mother's antibodies. The identification of these B cell epitopes is useful for diagnostic tests and may lead to future development of new therapeutic approaches based on peptide-specific immune intervention.