LMAN1 is a glycoprotein receptor, mediating transfer from the ER to the ER–Golgi intermediate compartment. Together with the co-receptor MCFD2, it transports coagulation factors V and VIII. Mutations in LMAN1 and MCFD2 can cause combined deficiency of factors V and VIII (F5F8D). We present the crystal structure of the LMAN1/MCFD2 complex and relate it to patient mutations. Circular dichroism data show that the majority of the substitution mutations give rise to a disordered or severely destabilized MCFD2 protein. The few stable mutation variants are found in the binding surface of the complex leading to impaired LMAN1 binding and F5F8D.MINT-7557086: lman1 (uniprotkb:P49257) and mcfd2 (uniprotkb:Q8NI22) bind (MI:0407) by X-ray crystallography (MI:0114)