Thus, an effect of UV on receptors and mediators of the opioid system may contribute to the antipruritic effect of phototherapy in ESRD, AD as well as in other pruritic conditions such as cholestatis, in which the MOR antagonists naloxone and naltrexone have also shown antipruritic efficacy and are recommended in the treatment for cholestasic pruritus (20). This evidence concerns the gene OPRM1 and Alzheimer disease.