MRGPRX2 and Alzheimer disease: Notably, a recent study has employed transcriptional profiling to establish a common signature for itchy psoriatic and AD skin, showing that many MC genes, such as tryptase, phospholipase A2 (PLA2), IL-6, IL-17, IL-22 and MRGPRX2, were commonly upregulated between the two types of pruritus [313].