44 ASPECTS OF PRENATAL DIAGNOSIS IN HEMOPHILIA A (HA) AND B (HB)

Abstract

Prenatal diagnosis (PD) of genetic diseases is the accepted preventive medical application of clinical genetics in many severe diseases such as HA and HB. We observed 408 women at risk for HA and 77 for HB coming respectively from 223 and 58 families. From 1987 we performed 72 PD out of 60 women on chorionic villus sampling (CVS) by transabdominal approach, free hand under continuous ultrasound guidance, at 10 weeks gestation. Even if earlier sampling is possible, a delaied procedure allowed to cut down the risks of miscarriage and of fetal limb abnormalities. In our hands the fetal loss risk is about 1.5%. We diagnosed 12 affected males, 24 healthy males and 28 female fetuses. At the beginning in 3 cases the sample was not sufficient for DNA analysis and, after CVS, in 2 cases the mother was uninformative and in 3 cases the mother was diagnosed as non carrier. We did not observe any malformation or pregnancy loss in the patients analyzed for hemophilia, probably related to the absence of other risk factors. The use of PCR for DNA analysis, allowed us to improve the carrier detection and PD of HA and HB reducing the time of analysis, increasing the informativity with the detection of sequence polymorphisms and using less chorionic tissue. The last 15 PD were performed by PCR. We gave a genetic counselling to 13 pregnant women at risk, avoiding the CVS in non carrier females. Therefore the acceptance of antenatal diagnosis increased: 8/60 women performed more then one PD (5/8 two CVS and 3/8 three CVS). On 10 pregnancies we analyzed the fetal sex by PCR obtaining the sex diagnosis in few hours. In 9/10 the result was confirmed by chromosomal analysis and only in 1 case we missed the diagnosis.