VWF and von Willebrand disease 3: The CTCK domain has four intrachain disulfide bonds including Cys2724-Cys2774, Cys2739-Cys2788, Cys2750-Cys2804 and Cys2754-Cys2806, and the single cysteine mutation in Cys2739-Cys2788, Cys2750-Cys2804 and Cys2754-Cys2806 result in type 3 VWD, demonstrating the crucial role of these three disulfide bonds in VWF biosynthesis, however, the role of the remaining disulfide bond Cys2724-Cys2774 remains unclear.