UROD and hepatoerythropoietic porphyria: We have previously established a heme-deficient zebrafish that is homozygous for a mutation in uroporphyrinogen decarboxylase (urod; also known as yquem) as a model for studying human hepatoerythropoietic porphyria (HEP) (Online Mendelian Inheritance in Man number 176100) and heme deficiency pathogenesis (Wang et al., 1998).