Abstract

A significant portion of newborns cared for in the neonatal intensive care unit or other ICUs, such as the cardiac ICU, have a medical condition with a genetic component, including congenital malformations, the leading cause of death in the NICU. In many cases, however, it is not clear which condition the child has or what can be done to help him or her. Genomic sequencing of sick newborns has the potential to bypass the prolonged journey to a diagnosis, improving the medical care of individual infants. Sequencing also has the potential to benefit others beyond the child whose genome is sequenced and his or her immediate family. Sequence data from sick newborns will expand medicine's understanding of genetic diseases, leading to improvements in clinicians’ ability to counsel family and to provide even more targeted care. Not only will more frequent use of sequencing lead to discovery of new genes; it will also provide unique insights into the full spectrum of known Mendelian genetic diseases, so‐called phenotypic expansion, when a gene previously recognized as associated with a phenotype is found to be associated with an expanded set of clinical features. Genetic and environmental changes that modify the expression of a genetic disease may also be elucidated.