[Primary immunodeficiencies. I. Classification and new etiopathogenic findings]

A current system of classification of primary immunodeficiency diseases, together with some recent discoveries in this field, are described. The most important development in elucidating the pathogenesis of primary immunodeficiencies was achieved in X-linked immunodeficiencies. This progress was made possible especially by the discovery of genes of most X-linked immunodeficiency diseases.