TREX1 and Aicardi-Goutieres syndrome: We identified proline-to-glutamine (P61Q) point mutations in TREX1 in two patients from two families presenting with features of AGS (Fig. 1A; AGS972: c.182C>A p.Pro61Gln homozygote; AGS1583: p.Pro61Gln/Arg114His compound heterozygote) [28].