Clinically, SAMHD1-related AGS differs from other AGS subtypes in that many patients, more than 20 described in the literature so far - ranging in age from neonate to adult, demonstrate a cerebral vasculopathy which can manifest both as stenotic, leading to a moyamoya appearance, and aneurysmal disease, which carry a high risk of intracerebral infarction and haemorrhage respectively[10–13]. This evidence concerns the gene SAMHD1 and Vascular dilatation.