A Preterm Infant with TTN Gene Mutation Presenting with Cardiac Tamponade and Hydrops Fetalis: A Case Report

Hydrops fetalis is a condition characterized by excessive fluid accumulation in the fetus, and is classified into immune and non-immune types depending on the underlying disease. Among cases of non-immune hydrops fetalis (NIHF), 15% to 20% are of cardiac origin, and genetic factors such as titin (<i>TTN</i>) gene mutations can contribute to cardiac dysfunction. We report the case of a preterm infant (29+2 weeks, 1,430 g) with hydrops fetalis who developed cardiac tamponade due to major pericardial effusion. Seven hours after birth, the heart rate suddenly decreased, and blood pressure could not be measured. Transthoracic echocardiography revealed substantial pericardial effusion and severely impaired cardiac function, and the preterm infant was diagnosed with pericardial tamponade. Emergency pericardiocentesis was performed, which led to hemodynamic stabilization. Genetic testing identified two heterozygous <i>TTN</i> mutations (c.13898A>T and c.27856G>T), with the latter presumed responsible for the observed cardiac dysfunction. The mother was found to carry the c.13898A>T mutation, but was asymptomatic. This case report highlights the importance of genetic testing in neonates with unexplained NIHF and cardiac complications. Identifying <i>TTN</i> gene mutations provides valuable insights into the underlying pathophysiology and guides clinical management.