148 Discordant congenital heart defects in monochorionic twins: risk factors and proposed pathophysiology

There is a six-fold increase in congenital heart defects (CHD) among monochorionic (MC) twins compared to singleton or dichorionic twin pregnancies. Though MC share genotype, discordant phenotypes related CHD have been described. Our objective was characterize the spectrum of context genetic results and clinical demographics for modern cohort provide insight into risk factors pathophysiology twins. Retrospective analysis all receiving prenatal fetal echocardiography at single institution from January 2010 – March 2020 (N=163) yielded 24 pairs (48 neonates) with (n=6 concordant CHD, n=18 CHD). Descriptive including frequencies, means, standard deviations were conducted maternal, diagnoses, neonatal variables. Continuous variables analyzed using Student t-test categorical Fisher Exact test. The most common lesions septal (50% 45% cohort) right (33% 18% cohort). Diagnostic testing abnormal 17% 6% pairs, no difference between groups (p=0.45). Six (25%) 2 4 discordant, complicated by twin-to-twin transfusion syndrome, recipient acquiring diagnosis testing. No significant association found development (p>0.05). This data supports environmental epigenetic influences versus genotypic pertinent early postnatal prognosis. illustrated higher rates (75%) this population, low incidence family history abnormalities (8.3%) our CHD.