FECH and X-linked lymphoproliferative disease: ALAS2 expression at the mRNA and protein level has been shown to be increased in peripheral blood samples of patients with FECH deficient EPP compared to healthy controls (Barman-Aksözen, et al., 2015) Gain-of-function mutations in ALAS2 lead to X-linked pprotoporphyria(XLP) associated with accumulation of PPIX during the erythropoiesis and a clinical presentation comparable to that of EPP (Whatley et al., 2008; Brancaleoni et al., 2016).