Challenges in the clinical understanding of genetic testing in birth defects and pediatric diseases.

Advances in prenatal/neonatal genetic screening practices and next generation sequencing (NGS) technologies have made the detection of molecular causes of pediatric diseases increasingly more affordable, accessible, and rapid in return of results. In the past, families searching for answers often required diagnostic journeys leading to delays in targeted care and missed diagnoses. Non-invasive prenatal NGS is now used routinely in pregnancy, significantly altering the obstetric approach to early screening and evaluation of fetal anomalies. Similarly, exome sequencing (ES) and genome sequencing (GS) were once only available for research but are now used in patient care, impacting neonatal care and the field of neonatology as a whole. In this review we will summarize the growing body of literature on the role of ES/GS in prenatal/neonatal care, specifically in neonatal intensive care units (NICU), and the molecular diagnostic yield. Furthermore, we will discuss the impact of advances in genetic testing in prenatal/neonatal care and discuss challenges faced by clinicians and families. Clinical application of NGS has come with many challenges in counseling families on interpretation of diagnostic results and incidental findings, as well as re-interpretation of prior genetic test results. How genetic results may influence medical decision-making is highly nuanced and needs further study. The ethics of parental consent and disclosure of genetic conditions with limited therapeutic options continue to be debated in the medical genetics community. While these questions remain unanswered, the benefits of a standardized approach to genetic testing in the NICU will be highlighted by two case vignettes.