CLOCK and porphyria: An in-depth knowledge of the mechanisms underlying the altered expression of circadian genes in heme synthesis disorders and a better definition of the pathophysiological alterations consequent to the derangement of the circadian clock circuitry in this context could shed light on important signaling pathways and could represent, in the near future, a therapeutic target in the hope of increasing the effectiveness of pharmacological treatments and improving the quality of life of patients suffering from porphyrias.