UROD and porphyria: In humans, an upregulation of the first gene in the haem pathway (ALAS) has been associated with increased severity of particular types of porphyria that produce uroporphyrin (To‐Figueras et al., 2011), so an increase in ALAS, along with a reduction in UROS and/or UROD would also be consistent with porphyrin production.