FAT1 and autosomal erythropoietic protoporphyria: To address this possibility, we studied 28 patients with congenital pituitary abnormalities of EPP and/or PSIS with WES, focusing on all 4 FAT genes, as well as DCHS1 and DCHS2. Three heterozygous variants in DCHS2 and 4 in FAT2 were identified and their locations on the proteins summarized in a schematic (Figure 1A).