Constitutively active Lyn kinase causes a cutaneous small vessel vasculitis and liver fibrosis syndrome

Neutrophilic inflammation is a hallmark of many monogenic autoinflammatory diseases. Here the authors report a case series of three unrelated boys with perinatal-onset of neutrophilic cutaneous small vessel vasculitis and systemic inflammation, and identify de novo truncating and missense variants in the Src-family tyrosine kinase LYN.