Prenatal diagnosis of hemophilia B by an immunoradiometric assay of factor
IX
L Holmberg, B Gustavii, E Cordesius, AC Kristoffersson, R Ljung, L Lofberg, P Stromberg and IM Nilsson
An immunoradiometric assay of factor IX was developed based on homologous
antibodies that arose in a hemophilic patient. With this assay, 11 of 12
patients with severe hemophilia B had factor IX antigen levels below 1 U/dl
and 6 patients with mild hemophilia B had various levels. Factor IX antigen
in 8 fetuses (16th-20th gestational week) aborted for therapeutic reasons
ranged from 1.8 to 10.0 U/dl. Six amniotic fluids contained 0.28-1.2 U/dl
factor IX antigen. Using the immunoradiometric assay, we could diagnose
hemophilia B prenatally in one fetus at risk. No factor IX antigen (<
0.2 U/dl) was detectable in the fetoscopic sample. After termination of the
pregnancy, analysis of blood from the abortus confirmed the diagnosis of
severe hemophilia B. We conclude that very sensitive immunologic assays,
such as the one described here, will prove useful in prenatal diagnosis of
severe hemophilia B, since determination of factor IX activity in
fetoscopic samples is unrealiable because of possible contamination with
thromboplastic material.
Volume 56,
Issue 3,
pp. 397-401,
09/01/1980
Copyright © 1980 by The American Society of Hematology
