Although the osteopenic phenotype of Notch3em1Ecan mice was secondary to increased RANKL, the administration of osteoprotegerin (OPG)-Fc was not considered for its correction because OPG-Fc causes osteopetrosis making the interpretation of the results difficult or not possible (Bargman et al., 2012). This evidence concerns the gene TNFRSF11B and osteopetrosis.