CARDIAC EXPRESSION OF SARCOPLASMIC-RETICULUM CALCIUM-ATPASE IN FETUSES WITH TRISOMY-21 AND TRISOMY-18 PRESENTING WITH NUCHAL TRANSLUCENCY

At 10-14 weeks of gestation about 80% of fetuses with chromosomal defe cts have abnormal accumulation of subcutaneous fluid in the nuchal reg ion that is visualized by ultrasonography as nuchal translucency. A po ssible cause for this translucency is cardiac dysfunction due to the a ssociated defects in the heart and great arteries. The aim of this stu dy was to investigate whether in cardiac tissue from trisomic fetuses, compared to normals, there is an alteration in the steady state level s of expression of the genes encoding sarcoplasmic reticulum calcium A TPase (calcium ATPase), which is known to be downregulated in postnata l heart failure. After termination of pregnancy at 10-18 weeks of gest ation, mRNA was extracted from cardiac tissue in 11 trisomy 21 and 4 t risomy 18 fetuses. Densitometric analysis of the Northern and slot blo ts was used to determine the steady state levels of expression of calc ium ATPase and the values from the trisomic fetuses were compared to t hose of 30 normal controls at 10-18 weeks. Calcium ATPase gene express ion did not change significantly with gestation at 10-18 weeks. In tri somic fetuses there was no significant decrease in calcium ATPase expr ession and expression levels of calcium ATPase were not related to inc reased nuchal translucency, However, the levels expressed in fetuses a re already very low and cardiac dysfunction as a potential etiological factor cannot be excluded.