Prenatal Genetic Diagnosis and Genetic Counselling in Couples at High Risk for Mucoviscidosis (cystic Fibrosis)

Correspondence to: Zoran L. Popa, e-mail: [email protected], Clinic of Obstetrics and Gynecology III, Victor Babes University of Medicine and Pharmacy Timisoara, Romania SUMMARY: Mucoviscidosis is the most common genetic autosomal recessive disease in Caucasian populations, a potentially lethal disease and therefore prenatal genetic diagnosis is essential for couples with increased risk of having children with mucoviscidosis. Our goal was to detect CFTR mutations in fetal genomic DNA isolated from amniotic fluid collected by amniocentesis and to establish if the fetus is healthy, just a carrier for one CFTR mutation or both alleles are affected and the fetus has mucoviscidosis. Based on family history or echographic investigations, 11 couples were selected for prenatal genetic diagnosis. The couples had previously children with mucoviscidosis, registered at the National Center of Mucoviscidosis in Timisoara who had been genetically tested and had both mutations identified, or had deceased children who had been diagnosed with mucoviscidosis (with or without molecular diagnosis). Both parents were also tested for CFTR mutations. Fetal genomic DNA was isolated from amniotic fluid collected by transabdominal amniocentesis in the 16th week of pregnancy or by early amniocentesis in the 14th week of pregnancy. Contamination of fetal DNA isolated from amniotic fluid with maternal DNA was excluded by STR genotyping. Genomic DNA from the parents was isolated from venous blood collected on EDTA. The genetic analysis for CFTR mutations was performed using the Elucigene CF29 kit and electrophoresis of ARMS-PCR products in agarose gel. The electrophoresis gels were visualized in UV light and after the interpretation of results, we identified 4 heterozygous genotypes ( 508/N, G542X/N), 6 normal genotypes and one compound heterozygote (621+1G>T/ 508). Prenatal diagnosis can be performed by ARMS-PCR using Elucigene CF29 kit only in cases where the detected genotype has at least one allele with 508 mutation or is a compound heterozygote for the other mutations detected by the kit, because this method doesn’t allow the detection of homozygous genotypes for mutations other than 508. The results obtained by prenatal diagnosis are essential for a complete and successful genetic counseling.