SummaryHeritable dysfibrinogenaemia (HD) is a rare qualitative disorder of fibrinogen (FGN). To better describe the clinical, laboratory and genotypic spectrum of HD, we evaluated 35 subjects identified at two UK centres using laboratory criteria. 12/35(34%) subjects with HD experienced bleeding (bleeding score >1 at any site), 3/35(9%) thrombosis and 20/35(57%) were asymptomatic. Amongst subjects with bleeding, symptoms were typically mild, at one anatomical site and seldom occurred after invasive procedures. All subject showed dry clot weight within or above laboratory reference interval (median 3Á2 g/l; range 1Á9-5Á1), reduced Clauss fibrinogen (median 0Á52 g/l; range 0Á21-1Á3), and prolonged thrombin (median 30Á7 s; range 21Á3-45Á7) and reptilase (median 42Á0 s; range 20Á0-68Á0) times. In all subjects, the prothrombin time ratio (PTR), determined by Sysmex CA-1500 coagulometer and Innovin activator, was abnormal (median 1Á42; range 1Á22-1Á61). The activated partial thromboplastin time ratio and PTR with other coagulometers and activators were comparatively insensitive to HD. All subjects with HD harboured heterozygous candidate nucleotide variations within known hotspots in the FGN genes. The HD variants identified in this cross-sectional study seldom have significant clinical manifestations and show similar laboratory features irrespective of genotype. Selection of coagulometer and PT activator may markedly affect the detection of new HD cases using coagulation screening tests.

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Residual donor leucocytes are responsible for many adverse transfusion reactions. Prestorage leucodepletion may ameliorate these effects and enhance product quality. We studied a bottom and top (BAT) system incorporating an integral filter for whole blood leucodepletion. Our evaluation assessed leucodepletion efficiency as well as in vitro SAG-M red cell quality and storage characteristics. Sixty-six units of blood were collected; test units into the Optipac-pLuS system and controls into the standard triple pack configuration. Test units were held for 4-6 h at room temperature (rt) or 12-18 h at 4 degrees C. The mean leucocyte counts for the SAG-M red cells in the quality and storage trial were 0.6 x 10(6) (rt hold), 0.05 x 10(6) (4 degrees C hold) and 2500 x 10(6) (controls). We observed no significant differences between the groups for Na+, ATP, 2,3-DPG, glucose, lactate and pH during the 49 d storage. The control group, however, showed a greater increase in haemolysis and K+ with time. Autologous in vivo 24 h red cell recovery, after 42 d storage, was > 75%. Adjustment of processing parameters in subsequent studies gave leucodepleted SAG-M red cells with minimal cell loss (9.19%) plus acceptable haemoglobin content (46-76 g/U) and haematocrit (54-62%). This system achieved > 3.5 log leucodepletion with all but one unit containing < 1 x 10(6) leucocytes. The product quality is good and the system suitable for routine use in blood centres.

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