Photosensitivity is the clinical hallmark of both erythropoietic protoporphyria (EPP) and X-linked dominant protoporphyria (XLDPP). Both disorders result from a hereditary dysfunction in heme biosynthesis. Disease onset is usually in early childhood. However, rare patients with late-onset EPP in association with a myeloproliferative disorder or myelodysplastic syndrome have been reported. In this issue, Livideanu et al. describe the first patient with late-onset XLDPP.