Molecular basis of haemophilia A.

Technologies in molecular biology have greatly advanced the knowledge regarding the origin of haemophilia A and the physiology of the factor VIII (FVIII) protein. A variety of different mutations in the FVIII gene have been identified and their effects on the FVIII protein described. It has been shown that the frequency of haemophilia A is due to a high mutation rate predominantly in male germ cells. A significant proportion is originating de novo in early embryogenesis from somatic mutations, a finding that has implications for genetic counselling. The life-cycle of the FVIII protein and its structure-function relationships are continuously clarified. Most recently it has been shown that FVIII clearance from the circulation is mediated by the low-density lipoprotein receptor-related protein (LRP) and cell-surface heparan sulphate proteoglycans (HSPGs). These findings raise hope for novel recombinant FVIII molecules with prolonged half-life that may improve therapies for haemophlia A.