Abstract
Inborn errors of metabolism are inherited conditions that block metabolic pathways. Despite major advances in our ability to diagnose these conditions, difficulties remain. Many conditions manifest before the results of the first newborn screening tests become available. Many newborn screening tests are not diagnostic, and further evaluation is needed. Newer variants of these conditions are constantly being identified, and there is a need to educate care providers to evaluate infants who may need referral and more extensive testing. Early initiation of medical care is critical to prevent or reduce significant morbidity and mortality.