In humans, polymorphisms in the SAMHD1 gene that introduce premature terminations in the open reading frame or missense mutations that inactivate phosphohydrolase activity are associated with Aicardi-Goutières syndrome (AGS), an early-onset neurological condition characterized by chronically elevated levels of type-I IFN in the cerebrospinal fluid [26]. This evidence concerns the gene SAMHD1 and Aicardi-Goutières syndrome.