HLA-G and Behcet disease: These studies showed: (i) that genetically determined low expression of the tolerogenic HLA-G molecules was associated with SZ severity implying that high level of HLA-G likely confers a protective effect against severe forms of SZ via NK inhibition41–44, as with sHLA-E in the current study; and (ii) that genetically determined HLA-G low expression confers protection against BD45,46, whilst high HLA-G levels increases BD risk, which is also parsimonious with the results of the present study.