With more specific reference to BDL, we may recall reports on the consequences on the expression of heme oxygenase (HO-1), along with the related heme metabolism and production of iron and carbon monoxide as byproducts of heme degradation [30], and on the heme-containing cytochrome P450 [9,31], all of which draw attention to the fluorescence of porphyrins in the serum as a possible early biomarker of injury in extrahepatic cholestasis. The gene discussed is HMOX1; the disease is extrahepatic cholestasis.