MabSelect SuReTM, used in the capture step of Reblozyl® (activin receptor type IIB to treat beta thalassemia) and Alprolix® (a coagulation factor IX for hemophilia B), is a resin functionalized with a tetrameric chains of alkali-stabilized protein A-derived ligand (of the Z-domain of staphycoccal protein A) produced in E. coli (Silva et al., 2018). This evidence concerns the gene F9 and hemophilia B.