A domain mutations in 65 haemophilia A families and molecular modelling of dysfunctional factor VIII proteins.
A variety of mutations are found in haemophilia A families. Those with circulating, dysfunctional protein can provide insights into structural determinants of factor VIII function. A molecular model based upon the crystal structure of the homologous A domains in caeruloplasmin enables predictions of molecular consequences of mutations. To identify haemophilic mutations in coding regions for three A domains of factor VIII and predict amino acid substitutions important for coagulant cofactor function, amplified DNA fragments from 188 unrelated haemophilia A families were screened for heteroduplex formation. Exons 1-19 were examined. 65 families were positive for 58 distinct mutations (39 novel) on DNA sequencing. 12 were non-missense mutations. 38 missense mutations were found in patients that circulate or potentially circulate dysfunctional factor VIII protein and are in an A domain molecular model. Of these 38, 12 have identical residues among all known species of factors V, VIII and caeruloplasmin. These 38 mutations have been localized onto a factor VIII A domain molecular model. Of these, 19 are in coiled, 15 in beta-pleated sheet, and two each in turns and alpha-helical structures. 15 substituted residues are on the surface, nine are partially on the surface and 14 are buried within the model structure. Mutant side-chain substitutions were inserted to predict changes in surface groups or, for buried residues, potential surface areas whose structure is probably disrupted by the substitution.
Liu
M
M
Puget Sound Blood Center and Department of Medicine, University of Washington, Seattle 98104-1256, USA.
Murphy
M E
ME
Thompson
A R
AR
D019943:Amino Acid Substitution; D005091:Exons / Q000235:genetics; D005169:Factor VIII / Q000235:genetics*; D005260:Female; D006467:Hemophilia A / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics*; D020125:Mutation, Missense / Q000235:genetics; D010375:Pedigree; D016133:Polymerase Chain Reaction / Q000379:methods; D017386:Sequence Homology, Amino Acid; D018909:src Homology Domains
D005169:Factor VIII