The clinical phenotype and the upregulation of β2-integrin function on neutrophils, and of ICAM-1 on skin endothelial cells and in the liver biopsies combined with the treatment response to dasatinib suggested a pivotal role of Lyn GOF mutations in endothelial dysregulation and as driver of vasculitis and liver fibrosis. Here, ICAM1 is linked to vasculitis.