Professor Katrin Õunap, University of Tartu
Associate Professor Tiia Reimand, University of Tartu
Associate Professor Vedran Stefanovic, Helsinki University Central Hospital, Finland
Prenatal screening (PS) aims to identify pregnancies at increased risk for chromosomal disorders. Significant changes in screening markers may also give insight into adverse pregnancy outcomes, or disease of fetus. Congenital heart defect (CHD) is the most common birth defect, affecting 3-13/1000 of live born infants. Majority of CHD are isolated congenital defects, but in 1- 4.6% cases CHD is one feature of genetic syndrome.
The aims of the present study were to establish the first trimester screening for Down syndrome in Estonia, to evaluate the potential of a contingent screening in our population of pregnant women; to investigate whether chromosomally normal fetuses with marked changes in maternal screening markers have an increased risk of congenital or genetic anomalies or delayed development at 2 years of age and to characterize rare monogenic genetic syndromes with CHD.
From 2006, two step contingent screening was introduced in Estonia. This protocol reduced considerably second-trimester sampling with positive impact (high detection rate -88.3%) on overall screening performance. The high-risk group of pregnant women achieved an earlier diagnosis and the low-risk group of pregnant women received earlier reassurance of normal results.
Children born to mothers with marked changes in screening markers and positive risk calculation for chromosomal anomaly should be followed by a pediatrician for additional consultation after birth, as they have a risk of 5.4% of having a congenital or genetic abnormality.
Most prevalent genetic syndrome with CHD was Noonan syndrome. The disease causing mutation in the PTPN11 gene was found in 28% of clinical cases, which confirm heterogeneity of Noonan syndrome and further investigations should be continued in subgroup of patients with classical features of syndrome. In study group also others genetic syndromes were diagnosed (e.g. LEOPARD and Holt-Oram syndrome). This study confirmed the importance to determine whether there is an underlying genetic pattern, because there may be involvement of some other organ system and it may be prognostic information for clinical outcome. Also there may be other family members for whom genetic testing is appropriate and it gives the recurrent risk for the family.