SAMHD1 and Aicardi-Goutieres syndrome: Methods: Six patients with genetically confirmed diagnoses were included: 2 patients with classic AGS (due to TREX1 and SAMHD1 variants), 2 patients with AGS/overlap Singleton-Merten (IFIH1-related), and 2 patients with ACP5-related spondyloenchondrodysplasia (SPENCD).