[X chromosome-linked lymphoproliferative syndrome (Duncan's disease)].

: The authors describe two cases of fatal disease with the picture of acute haemoblastosis in male siblings aged 6 and 18 months. By combined retrospective evaluation of the two cases the authors reach the conclusion that it is the first case of an X chromosome-linked lymphoproliferative syndrome (XLP) described in Czechoslovakia. The authors discuss laboratory and clinical findings (dynamic of specific antibodies against EBV, histopathological finding, clinical evaluation, hypergammaglobulinaemia IgM, paraprotein IgM, genetic examination) and evaluate the disease as the proliferative form of XLP in the clinical variant of fatal infectious mononucleosis. The paper provides also some basic information on XLP, incl. some new findings.