Genetic counselling, carrier detection, and prenatal diagnosis in hemophilia. A service experience.

Our experience over three years (1984-1986) is described in carrier detection and prenatal testing for hemophilia. We have analysed 50 families: 37 hemophilia A and 13 hemophilia B, 22 isolated cases and 28 familial. Eighty-three women belonging to this panel asked for a genetic risk. Pedigree and coagulation studies were performed to estimate genetic risks according to the Bayesian method. At this point, 40% of the females at risk were recognized carriers before the DNA analysis. Molecular biology allowed the detection of only 7% more carriers and the exclusion of 34%. In 19% of the cases, it was impossible to estimate the genetic risk because the families were uninformative for the DNA polymorphisms used. Twenty-two prenatal diagnoses were performed; 3 affected male fetuses were recognized by DNA analysis and pregnancies were terminated. Eleven healthy boys were born.