Mutations in SAMHD1 were first identified as being causative of Aicardi–Goutieres syndrome (AGS), a severe autoimmune disease [3], but later it was proposed as a tumor suppressor gene, since mutations in SAMHD1 are associated with different types of cancer [4,5] and its expression has been found to be inhibited in several types of tumors [6,7]. Here, SAMHD1 is linked to Aicardi-Goutières syndrome.