Congenital Chylothorax and Hydrops Fetalis: A Novel Neonatal Presentation of <i>RASA1</i> Mutation.

Abstract

Mutations in the <i>RASA1</i> gene are known to cause arteriovenous malformations (AVMs), with evidence of associated lymphatic malformations. We report for the first time, to the best of our knowledge, an infant with <i>RASA1</i> mutation presenting with hydrops fetalis and chylothorax, but without an associated AVM. Previously, researchers studying rodents have found chylothorax associated with <i>RASA1</i> mutations, and, in previous case reports, researchers have reported on infants with <i>RASA1</i> mutations born with hydrops fetalis and AVMs. In this report, we describe the case of a "late preterm" female infant born with nonimmune hydrops fetalis and congenital chylothorax who was detected to have a <i>RASA1</i> deletion on genetic workup. Although classically described phenotypes of <i>RASA1</i> mutations present with venous malformations, no such malformations were found in this infant on extensive imaging. This combination is a novel and nonclassic presentation of <i>RASA1</i> mutation. In cases of congenital chylothorax, especially with nonimmune hydrops fetalis, <i>RASA1</i> mutations should be considered as part of the differential diagnosis and genetic testing should be included as part of a complete workup to allow for screening for associated vascular anomalies.