Subject(s)
Epidermal Growth Factor/genetics , Factor VII/genetics , Mutation , Female , Homozygote , Humans , MaleABSTRACT
A missense mutation at codon 100 in the second epidermal growth factor-like domain, resulting in Gln100-->Arg, was detected in 19 out of 21 available severely factor VII (FVII) deficient patients in Norway. Seventeen patients were homozygous, and the two remaining were compound heterozygotes. In the homozygous patients, FVII antigen was measured to 10-28%, and activity to 0.6-6.5% of that in normal pooled plasma. Recombinant FVII containing the mutation was expressed transiently in CHO cells to a mean antigen level of 57% of the wild type FVII protein, and with a specific activity of 6% of wild type. The mutant protein had a 14-fold reduction in affinity for tissue factor (TF), whereas binding of FX seemed unaffected. In line with the experimental data, molecular modelling of the mutation based on the coordinates of the tissue factor/FVIIa complex showed that substituting arginine for glutamine disrupts the interface between the catalytic and second epidermal growth factor-like domains.
Subject(s)
Codon/genetics , Factor VII Deficiency/genetics , Factor VII/genetics , Point Mutation , Adolescent , Adult , Alleles , Amino Acid Sequence , Animals , Binding Sites , Blood Coagulation Tests , CHO Cells , Child , Child, Preschool , Cricetinae , DNA Mutational Analysis , Enzyme Activation , Factor VII/chemistry , Factor VII/metabolism , Factor VII Deficiency/ethnology , Factor X/metabolism , Female , Genotype , Glutamine/chemistry , Humans , Male , Middle Aged , Models, Molecular , Molecular Sequence Data , Norway/epidemiology , Protein Structure, Tertiary , Recombinant Proteins/biosynthesis , Thromboplastin/metabolism , TransfectionABSTRACT
In the aortic intima amyloid deposits are often associated with atherosclerotic plaques. In a recent study of one patient with aortic intimal amyloid the major fibril protein was an N-terminal fragment of apolipoprotein A1 (apoA1) consisting of 69 amino acid residues. In the present study, we have screened the apoA1 gene for mutations in autopsy cases with aortic intimal amyloid immunohistochemically positive for apoA1, using single stranded conformational polymorphism (SSCP) analysis and DNA sequencing. All cases except one had a normal apoA1 gene sequence. One case of exceptionally severe atherosclerosis combined with extensive intimal amyloid deposits showed an apoA1 deletion corresponding to Lys 107. Thus, wild type apoA1 is amyloidogenic but our findings suggest that the expression of a mutant apoA1-form may be associated with enhanced amyloidogenicity.
