BLM and Rothmund-Thomson syndrome: Other entities include Bloom syndrome (OMIM #210900), caused by mutations in BLM gene [71]; Rothmund-Thomson syndrome (OMIM #268400), most often due to variants in RECQL4 gene [72]; and Epidermolysis Bullosa Simplex (OMIM #131900), due to mutations in 18 different genes [73], which present mottled pigmentation with similar poikiloderma.