Fetal phenotypes emerge as genetic technologies become robust

Prenatal genomic evaluation of the fetus is available at decreasing cost and with a faster turnaround time. However, fetal genotype-phenotype correlations are in their infancy. By comparison, pediatric and adult genotype-phenotype databases are well established and publicly accessible. A similar system for fetal genomics is lacking. When a fetal anomaly is identified by ultrasound imaging, a genetic diagnosis provides important information. However, fetal prognostic counseling is problematic if the only available information is based on outcomes following postnatal diagnoses. The same conditions identified prenatally may have more benign or more deleterious outcomes. Also, the condition may evolve over the pregnancy itself. As genomic testing increasingly examines fetal DNA at a single nucleotide level, the concomitant in utero phenotype deserves equal attention. Often, the reports of fetal phenotype are limited. Among sonologists, an increased awareness of attaining and communicating detailed fetal phenotypes is needed. The interpretation of expanded prenatal sequencing is reliant on deeper fetal phenotyping. The information gained significantly impacts clinical care and understanding of fetal development. This case series highlights: the broad spectrum of fetal phenotypes for known genetic conditions, phenotype progression during pregnancy, and the need to supplement systematic imaging with descriptive details when assessing fetuses with malformations.