Blended Phenotypes From a

Fetal hydrops can stem from immune or nonimmune causes. Immune causes often involve red cell alloimmunization, whereas nonimmune causes encompass structural malformations, aneuploidy, infections, lymphatic system disorders, genetic syndromes, and more. In a rare and complex case, we encountered a fetal hydrops presentation characterized by blended phenotypes, indicating both a genetic and an underlying immune etiology. The mother, Rhesus negative, presented with a history of adverse obstetric events. At 21 weeks, the current fetus was diagnosed with hydrops. Maternal blood tests unveiled Rhesus alloimmunization, featuring a positive indirect Coombs test at a 1:512 dilution and the presence of anti-D, anti-C, and anti-E antibodies. Fetal blood sampling revealed an O-positive blood group with a hemoglobin level of 10 gm/dL. Despite administering intrauterine transfusion to the fetus, there was no improvement; instead, the fetal hydrops worsened, accompanied by the emergence of nuchal and axillary masses. Exome sequencing of fetal DNA revealed the fetus was homozygous for a pathogenic variant in the