ALAS1 and porphyria: Under fasting conditions, cellular glucose levels are low, the PGC-1α gene expression is up-regulated and, in turn, increases transcription of the ALAS-1 gene [9,10], which is likely the reason for fasting as a trigger of acute porphyria attacks and for the benefits of glucose infusions to attenuate the severity of acute attacks of porphyria [11,12].