Figure 1

Concept of EDGE. An inborn error of metabolism, such as complete deficiency of a critical enzyme, has catastrophic consequences, whereas mildly diminished enzyme levels may be clinically silent except under stress conditions (eg high-dose chemoradiotherapy). HSCT=hematopoietic stem cell transplantation; HVOD=hepatic veno-occlusive disease (modified with permission from Summar et al⁵).