Altered apoptosis levels in hearts of human fetuses with Down syndrome

Abstract

Objective: We sought to test the hypothesis that apoptosis is a method of remodeling in second-trimester fetal heart development. We also hypothesized that hearts from fetuses with Down syndrome would have different levels of apoptosis than would control hearts, associated with their abnormal heart development. Study Design: We obtained hearts from fetuses between 14 and 23 weeks’ gestation with Down syndrome without anomalies (n = 10) and with the atrioventricular canal defect (n = 5). These hearts were compared with control hearts without anomalies (n = 5 ). Hearts were subjected to in situ end-labeling of deoxyribonucleic acid to test for evidence of apoptosis. The apoptotic indices were compared by anatomic location. Results: Apoptotic nuclei were observed in each anatomic location in every category. The apoptotic indices were significantly lower in the atrial myocardial tissues of fetuses with Down syndrome than in control preparations (P < .05). The apoptotic index did not differ significantly in the atrial septum, ventricular myocardium, or ventricular septum. Conclusions: Apoptosis occurs in human fetal hearts during the second trimester. The different levels observed in our study suggest a different remodeling process in hearts of fetuses with Down syndrome than in hearts of control fetuses. Further study is needed to determine whether the different level of apoptosis associated with Down syndrome is due to the abnormal karyotype or to the presence of an anomaly. (Am J Obstet Gynecol 1998;179:962-5.)