Prekallikrein deficiency is a rare autosomal recessive disease not considered to be associated with a tendency for bleeding, despite marked prolongation of activated partial thromboplastin time. Currently, six kinds of mutations in the prekallikrein gene are known to be associated with prekallikrein deficiency. In this report, we describe a patient with idiopathic thrombocytopenic purpura who was recognized to have severe prekallikrein deficiency. Molecular analysis of the patient's prekallikrein gene showed a homozygous Trp499Stop nonsense mutation that has not been reported previously. The mutant allele is predicted to encode a truncated protein lacking half of the catalytic domain of prekallikrein, suggesting that the truncated protein causes prekallikrein deficiency in the patient.

The newly developed XE-2100

T he new ly developed X E-2100 haematolog y analyser can provide complete blood counts, leukocyte diå erentials, perform reticulocyte analysis, and obtain quantitative data on nucleated red blood cells ( N RBCs) . In this study, we evaluated the basic perf ormance of this instrument using routinely obtained blood specimens treated with ethylenediaminetetraacetic acid-2K . Reproducibility, carryover, stability during storag e at 4 ë C and room temperature, and accuracy were evaluated. In this evaluation, reproducibility was g ood and little carryover was f ound. A ccurate measurements were possible f or up to 48 h of storag e. A g ood correlation between nding s with the X E-2100 and SE-9000 haematolog y analysers was f ound f or complete blood count on 210 samples tested. T he leuk ocyte diå erential obtained with the X E-2100 correlated well with eye counts and with the results obtained with the SE-9000 automated haematolog y analyser, with r values over 0.9 f or the percentag es of neutrophils, lymphocytes and eosinophils. T he precision and accuracy of N RBC and reticulocyte counts by the X E-2100 were satisfactory. W e used the X E-2100 to obtain diå erential counts f or bone marrow aspirates, and g ood correlations with manual diå erentials were obtained f or total nucleated cell count, percentag e of myeloid cells and percentag e of erythroid cells. T he perf ormance of the X E-2100 was excellent, and this instrument should be able to provide reliable data to clinical laboratories.