Uncovering the Etiologies of Non-immune Hydrops Fetalis

Non-immune hydrops fetalis (NIHF) is diagnosed on prenatal ultrasound when abnormal fluid collections are seen in the fetus. NIHF carries significant risks of stillbirth, preterm birth, and postnatal morbidity and mortality, particularly when the etiology remains unknown and critical opportunities for focused care and implementation of treatments are missed. In contrast, when an etiology is found, both pre- and postnatal management are directly impacted: counseling is focused, risks to the fetus and neonate are accurately anticipated, surveillance and in utero available treatments such as intrauterine transfusions are implemented, and postnatal treatments are promptly initiated to optimize outcomes. The overarching hypothesis is that discovering the precise etiologies of NIHF will create critical opportunities to improve outcomes through earlier, targeted pre- and postnatal care. Several important steps remain in order to uncover the genetic etiologies for cases remaining unsolved and improve care for these pregnancies. The study team proposes a multicenter collaboration to discover additional genetic diseases and novel variants underlying NIHF in a prospectively enrolled, large and diverse cohort utilizing whole genome sequencing (WGS) and RNA sequencing. The team will further perform comprehensive phenotyping to: a) collect detailed postnatal phenotypes and outcomes, b) re-analyze WGS data utilizing postnatal phenotype to identify diagnoses missed when sequencing algorithms incorporated only phenotype, and c) expand the phenotypes of all genetic in utero in utero diseases the investigators identify to optimize prenatal diagnosis and yield of genomic testing during pregnancy. Such a focused and comprehensive approach to the evaluation and diagnosis of NIHF has not previously been performed, particularly in a large and diverse cohort, and it is expected that this work will significantly improve the ability to understand and reshape the perinatal care for NIHF. This work will lay the foundation for redefining the approach to prenatal diagnosis, management, in utero and postnatal care for NIHF, and will create future opportunities to develop novel diagnostic algorithms and approaches to manage the complications of specific diseases underlying in utero NIHF.