Sex-linked hereditary thrombocytopenia with immunological defects

14 cases of severe thrombocytopenia in one family are presented. Case histories, clinical examination, analyses of platelets, haemoglobin, reticulocytes, leucocytes, eosinophilocytes, differential counts of leucocytes, serum immunoglobulin IgA, IgM, IgG, IgE concentrations, complement fixing platelet antibodies, isohaemagglutinins, colour perception, determination of red cell and serum groups as well as HL-A types were obtained from a total of 59 members of the family. The in vitro blast transformation response of blood lymphocytes was studied in 6 patients and 45 relatives. The pattern of transmission of the disease was in full agreement with X-linked recessive inheritance. Investigation of the immune system revealed impaired responses to microbial antigens in the 6 patients so studied. All relatives examined had normal haematological status, whereas approximately half showed a subnormal response to one microbial extract. The low responders were evenly distributed within the family, and it was not possible to correlate low response and presumed carrier state.