Mutations in the β3 gene giving rise to type I Glanzmann thrombasthenia in two families in Portugal

Glazzmann thrombasthenia is an inherited bleeding syndrome in which an absence of platelet aggregation is associated with quantitative or qualitative deficiencies of the alphaIIbbeta3 integrin. We now describe biochemical and molecular studies on two Portuguese families where platelets lack both surface and intracellular pools of alphaIIbbeta3. DNA extraction was followed by PCR-SSCP analysis of all exons and intronic boundaries in the alphaIIb and beta3 genes. Migration abnormalities were found for PCR fragments encompassing exon 12 (family 1) and exon 10 (family 2). For patient 1, there was a homozygous G to T transition at position 1846 which resulted in a stop codon at codon 616 in the beta3 gene. For patient 2, direct sequencing revealed a homozygous 1347C insert which led to a stop codon at codon 444 in the beta3 gene. For both patients a single mutated allele was inherited from each parent. Evidence is accumulating that nonsense mutations leading to a truncated beta3 may be a frequent cause of type I Glanzmann thrombasthenia in the Iberian peninsula.

Review of the quality monitoring methods used by countries using or implementing universal leukoreduction

Several countries are implementing or have implemented universal leukoreduction (ULR). Specifications, leukocyte counting, and monitoring methods were essential elements in achieving process confidence and conformance. A review of these protocols is presented. A questionnaire was prepared, agreed, and circulated, and responses were collated. Different specifications have been adopted as well as disparate approaches to leukocyte counting and residual leukocyte monitoring. Parametric, nonparametric, and pass-rate methods of analysis were used. Despite these differences, users were satisfied that the methodologies were providing assurance of component quality.

Utility of flow cytometry immunophenotyping and DNA ploidy studies for diagnosis and characterization of blood involvement in CD4+ Sézary's syndrome

BACKGROUND AND OBJECTIVES

The exact immunophenotypic criteria for the identification of Sézary cells in the blood are still poorly defined.

DESIGN AND METHODS

We analyzed the immunophenotype and DNA cell content of blood T cells in a series of 18 consecutive cases of Sézary's syndrome (SS), 21 normal individuals and 10 patients with reactive erythroderma, and correlated them with molecular and morphological findings.

RESULTS

Phenotypically abnormal CD3+/TCRalphabeta+/CD4+ T cells were found in all SS patients but in none of the reactive erythroderma cases; small diploid, or less frequently hypodiploid Sézary's cells coexisted with large nearly tetraploid Sézary's cells in some cases. The most frequent phenotypic aberrations consisted in decreased expression of CD3/TCRalphabeta (94%), CD4 (94%), CD7 (100%) and/or CD2 (83%). In addition, Sézary's cells were constantly CD28+ and CD5+ and they did not express natural-killer associated (NKa) antigens. Phenotypic heterogeneity was a common finding and phenotypic changes over time were frequently observed. In contrast to what was found in patients with reactive erythroderma, flow cytometry analysis of the T-cell receptor (TCR) repertoire revealed a major TCR-Vbeta expansion in all SS cases.

INTERPRETATION AND CONCLUSIONS

The presence of CD28+/CD5+/NKa-/CD4+ T cells expressing abnormally low levels of CD3, TCRalphabeta, CD4, CD7 and/or CD2 would support the diagnosis of SS in patients with erythroderma. Further analyses on larger series of patients are necessary in order to cover less frequent phenotypic patterns, establish the preferential usage of specific TCR-Vb families and investigate the specificity of these phenotypic abnormalities for diagnosing SS.

The heterogeneity of type IIA von Willebrand's disease: studies with protease inhibitors

The absence of large von Willebrand factor (vWF) multimers from plasma is a characteristic of Type IIA von Willebrand's disease (vWD) and is thought to contribute to the clinical expression of this disorder. Recently, three IIA patients have been reported in whom intermediate and large multimers could be restored if blood were collected in 5 mm EDTA, 6 mmol/L N-ethylmaleimide, and 1 mmol/L leupeptin. This suggested that absence of large multimers resulted from in vitro proteolysis. We have now collected blood from ten Type IIA vWD patients in these inhibitors but were not able to detect large multimers in the plasma of any of them. In addition, intermediate-sized multimers were reduced or completely absent in all. The inclusion of inhibitors in the citrate anticoagulant, as compared to citrate alone, was found to increase the relative proportion of intermediate multimers in some patients but had no effect in others, and in none did it restore large multimers to plasma. The results with platelet vWF were more varied. Four patients showed an absence or decrease of large multimers, whereas in seven patients large multimers were present. When compared with citrate anticoagulant alone, the inclusion of inhibitors in the anticoagulant had little or no effect on the platelet multimeric pattern. 1-Deamino-8-D-Arginine Vasopressin (DDAVP) was administered to six patients from five families. Two patients from one family showed complete correction and a third patient showed almost complete correction of her bleeding time. Two patients showed minimal correction and one showed no detectable correction. An increase in multimer size after DDAVP tended to be associated with correction of the bleeding time. However, in no case did the largest multimers appear in plasma even in patients with complete bleeding time correction. The presence or absence of inhibitors in the anticoagulant had little or no effect on the multimeric pattern after DDAVP. These results indicate that Type IIA vWD is a heterogeneous disorder in which absence of largest and intermediate multimers is an in vivo phenomenon.