SAMHD1 and stroke disorder: Furthermore, AGS symptoms can present in a heterogeneous fashion, with additional neurological phenotypes observed in specific genetic subtypes, including ADAR1-related bilateral striatal necrosis (10, 11), ADAR1, IFIH1 and RNASEH2B-related spastic paraplegia (12) and SAMHD1-related cerebrovasculopathy and stroke (13–16).