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Dor F.J.M.F.,Erasmus MC | Massey E.K.,Erasmus University Rotterdam | Frunza M.,Babes - Bolyai University | Frunza M.,Academic Society for the Research of Religions and Ideologies SACRI | And 11 more authors.
Transplantation | Year: 2011

In the literature, varying terminology for living organ donation can be found. However, there seems to be a need for a new classification to avoid confusion. Therefore, we assessed existing terminology in the light of current living organ donation practices and suggest a more straightforward classification. We propose to concentrate on the degree of specificity with which donors identify intended recipients and to subsequently verify whether the donation to these recipients occurs directly or indirectly. According to this approach, one could distinguish between "specified" and "unspecified" donation. Within specified donation, a distinction can be made between "direct" and "indirect" donation. © 2011 by Lippincott Williams & Wilkins.

Cvejic A.,University of Cambridge | Cvejic A.,Wellcome Trust Sanger Institute | Haer-Wigman L.,Sanquin Research | Haer-Wigman L.,University of Amsterdam | And 59 more authors.
Nature Genetics | Year: 2013

The blood group Vel was discovered 60 years ago, but the underlying gene is unknown. Individuals negative for the Vel antigen are rare and are required for the safe transfusion of patients with antibodies to Vel. To identify the responsible gene, we sequenced the exomes of five individuals negative for the Vel antigen and found that four were homozygous and one was heterozygous for a low-frequency 17-nucleotide frameshift deletion in the gene encoding the 78-amino-acid transmembrane protein SMIM1. A follow-up study showing that 59 of 64 Vel-negative individuals were homozygous for the same deletion and expression of the Vel antigen on SMIM1-transfected cells confirm SMIM1 as the gene underlying the Vel blood group. An expression quantitative trait locus (eQTL), the common SNP rs1175550 contributes to variable expression of the Vel antigen (P = 0.003) and influences the mean hemoglobin concentration of red blood cells (RBCs; P = 8.6 × 10-15). In vivo, zebrafish with smim1 knockdown showed a mild reduction in the number of RBCs, identifying SMIM1 as a new regulator of RBC formation. Our findings are of immediate relevance, as the homozygous presence of the deletion allows the unequivocal identification of Vel-negative blood donors. © 2013 Nature America, Inc. All rights reserved.

Ghevaert C.,National Health Service NHS Blood and Transplant | Ghevaert C.,University of Cambridge | Herbert N.,National Health Service NHS Blood and Transplant | Hawkins L.,National Health Service NHS Blood and Transplant | And 13 more authors.
Blood | Year: 2013

Fetomaternal alloimmune thrombocytopenia, caused by the maternal generation of antibodies against fetal human platelet antigen-1a (HPA-1a), can result in intracranial hemorrhage and intrauterine death. We have developed a therapeutic human recombinant high-affinity HPA-1a antibody (B2G1Δnab) that competes for binding to the HPA-1a epitope but carries a modified constant region that does not bind to Fcγ receptors. In vitro studies with a range of clinical anti-HPA-1a sera have shown that B2G1Δnab blocks monocyte chemiluminescence by >75%. In this firstin- man study, we demonstrate that HPA-1a1b autologous platelets (matching fetal phenotype) sensitized with B2G1Δnab have the same intravascular survival as unsensitized platelets (190 hours), while platelets sensitized with a destructive immunoglobulin G1 version of the antibody (B2G1) are cleared from the circulation in 2 hours. Mimicking the situation in fetuses receiving B2G1Δnab as therapy, we show that platelets sensitized with a combination of B2G1 (representing destructive HPA-1a antibody) and B2G1Δnab survive 3 times as long in circulation compared with platelets sensitized with B2G1 alone. This confirms the therapeutic potential of B2G1Δnab. The efficient clearance of platelets sensitized with B2G1 also opens up the opportunity to carry out studies of prophylaxis to prevent alloimmunization in HPA-1a-negative mothers. © 2013 by The American Society of Hematology.

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