CONCEPT FOR PRENATAL-DIAGNOSIS IN FAMILIES WITH CYSTIC-FIBROSIS AND DECEASED INDEX PATIENTS

In our genetic counselling unit 30 out of 96 couples who sought prenatal diagnosis (PD) for cystic fibrosis (CF) had lost their affected child before. Thus, in some cases PD has to be carried out by evaluation of amnion fluid enzymes. Our results of 64 PD using this technique demonstrate a rate of 1.6% false-negative and 6.3% false-positive prognoses. However, genomic linkage analysis (GLA) is possible, when Guthrie blood spots or cryostate tissue specimen of the deceased indexpatient are available. We report on three examples of successful GLA in CF families without a living patient using PCR and Southern technique (SBT). Strong linkage disequilibrium between KM 19 and XV-2c RFLP and the CF gene enables calculation of the CF risk, when the parental CF chromosomes cannot be identified by GLA. For this purpose CF haplotype distribution in GDR population is reported.