Thomas et al. [137] also reported an interferon response and toxicity associated with accumulation of extrachomosomal L1-related single-stranded DNAs in neurons derived from hESCs lacking TREX1, a DNA exonuclease mutated in patients with Aicardi-Goutières syndrome (AGS), a rare childhood Type I interferonopathy involving loss of brain white matter [138]. Here, TREX1 is linked to Aicardi-Goutieres syndrome.