Immunogenetics of the antiphospholipid syndrome

Genetic factors are important in the development of APS. This is demonstrated by animal models, by the familiar occurrence of this syndrome and by its association with various HLA alleles. Immunogenetic studies suggest that APS is an entity distinct from SLE, even if it can appear in the course of this latter disease. The genetic predisposition to APS can be at least in part explained with an influence of certain HLA alleles. However, these alleles could only be apparent because of their linkage disequilibrium with an as yet unidentified primarily involved HLA-locus, or they could act in co-operation with other genes, even residing outside the MHC. In this chapter, studies on the immunogenetic predisposition to APS and to the production of the aPL are summarised and discussed.