Systemic vasculitides: immunogenetics and familial clustering.

The systemic vasculitides (SV) are a heterogeneous group of rare affections characterized by a primary process of inflammation and damage of the blood vessel wall. Their etiopathogenesis is still unknown, but a complex interaction of multiple factors, such as age, sex, ethnic background, immunogenetic mechanisms and environmental influences, is probably involved. A genetic predisposition to SV is suggested by both familial case clusters and immunogenetic studies. The available reports on familial SV via the PubMed (National Library of Medicine) and Biosis indices, as well as personal observations, are summarized here. Furthermore, the evidence for a role of genetic predisposing factors is reported. The literature review suggests that several SV such as giant cell arteritis, Takayasu arteritis, Kawasaki disease, Wegener's granulomatosis and Henoch-Schönlein purpura, are governed by multiple genes encoding host defence molecules and probably triggered by environmental agents. Genetic factors seem to be implicated not only in the susceptibility, but also in the severity and outcome of SV.