This study found no benefit of the routine use of minidose warfarin for prophylaxis of central vein' catheter thrombosis in patients with haematological malignancies and therefore does not support the routine use of minidose warfarin for prophylaxis in such patients.

Transfer of donor immunity has been demonstrated in animal models of both allogeneic and syngeneic bone marrow transplantation (BMT). Clinical case reports have suggested that human autoimmune disease may be similarly transferred. However, it is difficult to completely exclude autoimmune phenomena associated with graft-versus-host disease (GVHD) as previously reported cases are of allogeneic BMT. In addition, the onset of autoimmunity has been distantly related to the timing of the transplant, perhaps because of the immunosuppression used for prophylaxis and treatment of GVHD. We describe a patient in whom the development of psoriasis shortly after receiving syngeneic bone marrow from a psoriatic donor and its recurrence with arthropathy following a second syngeneic BMT provide more direct evidence for the adoptive transfer of human autoimmune disease, probably by T cells.

Summary. The RUNX1 (AML1, CBFA2) gene is a member of the runt transcription factor family, responsible for DNA binding and heterodimerization of other non-DNA binding transcription factors. RUNX1 plays an important part in regulating haematopoiesis and it is frequently disrupted by illegitimate somatic recombination in both acute myeloid and lymphoblastic leukaemia. Germline mutations of RUNX1 have also recently been described and are dominantly associated with inherited leukaemic conditions. We have identified a unique point mutation of the RUNX1 gene (A107P) in members of a family with autosomal dominant inheritance of thrombocytopenia. One member has developed acute myeloid leukaemia (AML).

Falsely high automated platelet counts in a patient with aplastic anemia were found to be due to increased resistance of the red blood cells to urea lysis. The patient's blood group Jk(a-b-). Further investigation revealed that this phenomenon occurred with all of eight bloods of the phenotype Jk(a-b-) but not with red blood cells of other phenotypes tested. We therefore report an association of a rare blood group phenotype with unusual red blood cell behavior in vitro.

The Philadelphia chromosome (Ph') is found in the blood cells of about 90% of patients with chronic myeloid leukaemia (CML) and usually results from the reciprocal chromosome translocation t(9;22). This translocation relocates the proto-oncogene c-abl, normally found on chromosome 9q34, to within the breakpoint cluster region (bcr) on chromosome 22q11 (refs 3-8). The juxtaposition of c-abl and the 5' portion of bcr appears to be the critical genomic event in CML and results in a novel 8-kilobase (kb) fused abl/bcr transcript and a c-abl-related protein of relative molecular mass 210,000 (ref.11). About 10% of adult patients diagnosed as CML lack the Ph' chromosome; they represent a heterogeneous group of disorders which are difficult to diagnose precisely. We have examined five patients with CML whose leukaemic cells have a normal karyotype. We report here that two of the patients showed the same genomic change as occurs in Ph'-positive CML, but the change resulted from a mechanism other than chromosomal translocation. The remaining three patients showed no genomic rearrangement. This genomic diversity correlated with the clinical differences between the patients.