Since VKCFD arises from a single genetic defect of either γ-glutamyl carboxylase (GGCX) or vitamin K 2,3-epoxide reductase complex (VKORC) - two proteins of the vitamin K cycle - in the revised classification it obviously falls in the second subgroup. Here, GGCX is linked to vitamin K-dependent clotting factors, combined deficiency of, type 1.