title: Polymorphism of normal factor IX detected by mouse monoclonal antibodies.
abstract: Hemophilia B is an X-chromosomal recessive disease due to deficiency of coagulation factor IX. Three monoclonal antibodies against factor IX were prepared and used to develop immunoradiometric assays (IRMAs) of factor IX antigen (IX-Ag). IX-Ag was measured in 65 normal individuals with one IRMA based on polyclonal anti-IX antibodies and two IRMAs based on three monoclonal anti-IX antibodies. One of the monoclonal antibodies differed in specificity since it neutralized less than 50% of the clotting activity of factor IX (IX-C), whereas the other two monoclonal antibodies neutralized 80-95%. When the former antibody was used as the solid phase in IRMA, two groups of normal individuals were distinguished: group A with measurable IX-Ag, and group B without demonstrable IX-Ag. There were no differences between the groups either in IX-C or in IX-Ag measured with polyclonal antibodies. A subgroup comprising only women could be distinguished in group A, in whom intermediate IX-Ag concentrations were found. Family studies showed the group B variant of normal factor IX to be transmitted according to the pattern of X-linked recessive inheritance. The allelic frequency of group A was 0.66, and that of group B was 0.34.
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D000818:Animals; D000911:Antibodies, Monoclonal; D005164:Factor IX / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D015949:Factor IXa; D005260:Female; D002836:Hemophilia B / Q000097:blood; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D010375:Pedigree; D011110:Polymorphism, Genetic; D011863:Radioimmunoassay
chemical_list: D000911:Antibodies, Monoclonal; D005164:Factor IX; D015949:Factor IXa