p57Kip2, as reported above, is abundantly expressed in placental tissues, and, therefore, its dysregulated expression, in humans, is associated with placental mesenchymal and vascular proliferative disorders, such as placental mesenchymal dysplasia (PMD), and complete and partial hydatidiform moles [172,173]. This evidence concerns the gene CDKN1C and Pelizeaus-Merzbacher spectrum disorder.