Objective: To study the functional change of an Ala737-->Glu substitution mutant of vWF and the molecular pathological mechanism of this mutant in the type 2A vWD.
Methods: The expression plasmid pSVvWF containing full-length cDNA of vWF was used to site direct mutagenesis by polymerase chain reaction (PCR) and transitorily expressed in the COS-7 cells, vWF: Ag in the supernatant and the cell lysate between wild type and pSVAla737Glu vWF were measured. vWF polymers of the platelet of the patient with the mutation and response to DDAVP treatment of the patient were observed.
Results: vWF: Ag level of pSVAla 737Glu vWF was 76.4% and 98.8% of the wild types in the supernatant and cell lysate, respectively. The polymer pattern of extracellular pSVAla737Glu vWF was indistinguishable from that of the wild type, containing all kinds of molecular weight. Increased vWF antigen levels was observed in the patients after DDAVP treatment.
Conclusion: This mutant did not change the assembly and secretion of vWF. The mutant of vWF Ala737-->Glu resulted in Group II type 2A vWD.