The chapter gives overview of a very rare progressive genetic multi-organ small-vessel disease affecting retina and brain, but also otherhighly vascularized organs, mostly kidneys and liver. Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is inherited in autosomal dominant manner and caused by heterozygous C-terminal frameshift mutation in TREX1 gene.The clinical phenotype is largely based on details from an international study in less than 100 mutation carriers from 11 unrelated families. Clinically RVCL-S hasremained under-recognized. The vascular retinopathy is presented from age 20, followed by liver and kidney disease, and clinical manifestations of global and focal brain dysfunctionaround age 50 and leading to death in 10-15 years. On magnetic resonance imaging white matter lesionscan be confused withcentral nervous system tumours, multiple sclerosis,or other inherited small vessel diseases with prominent white matter lesions. There is no established treatment for RVCL-S