Histological comparison, however, of products of conception from aPL-positive and negative patients with recurrent early miscarriage has shown a specific defect in decidual endovascular trophoblast invasion in patients with APS,4 whereas placental infarction is not specific to patients with APS.5 Furthermore, aPL have been shown to have direct effects, both in vitro and in vivo, on endometrial and trophoblast cells resulting in impaired implantation and placental development (reviewed in6). This evidence concerns the gene FASLG and autoimmune polyendocrinopathy.