8 6 4 12 12 2 10 10 0 8 8 6 6 4 4 2 2 0 0 D C c Antigen
Fig 3. Rh antigen expression predicted from genotyping that differentiates patients whose red cells express variant, conventional antigens or are antigen-negative (n=10 patients).
Molecular genotyping 12
10 8
First, DNA was isolated using the automated BEXS 12 Bead Extraction System. The RBC-FluoGene vERYfy eXtend plate was then set up with the Pipetting Unit PiU 1. This vERYfy eXtend kit has oligonucleotide mixes that are pre-aliquoted and dried in the PCR plates, which allows specific genetic markers to be amplified. The oligonucleotide mixes contain primers and probes, which are labelled with different fluorescent dyes. Red cell genotyping was performed on
12 12 10 10 8 8 6 4 12 12 2 10 10 0 8 8 6 6 4 4 2 2 0 0 K k Jka Jkb Fya Fyb M Antigen Fig 4. Antigen expression of clinically significant antibodies in known SCD patients (n=10 patients). 44 APRIL 2024
WWW.PATHOLOGYINPRACTICE.COM N S s U 0 0 2 2 6 6 4 4 2
Antigen negative Altered antigen
0 Partial antigen Conventional antigen
n The author wishes to acknowledge the help received from A Rainey and O Shelest (Northern Ireland Blood Transfusion Service) and C Williamson (BHSCT Specialist Red Cell Laboratory).
References 1 Kavanagh PL, Fasipe TA, Wun T. Sickle Cell
Disease. JAMA. 2022 Jul 5; 328 (1): 57–68. doi: 10.1001/jama.2022.10233.
2 Davis BA., Allard S, Qureshi A et al.; British Committee for Standards in Haematology. Guidelines on red cell transfusion in sickle cell disease. Part I: principles and laboratory aspects. Br J Haematol. 2017 Jan; 176 (2): 179–91. doi: 10.1111/ bjh.14346.
This article is based on a poster presented at the IBMS Congress 2023 event, held last September at the International Convention Centre in Birmingham.
10 known SCD patients tested using the Inno-train PCR (qPCR) molecular method using the FluoGene vERYfy eXtend kit to accurately determine the genotype of these multiple-transfused patients ensuring appropriate blood selection for future transfusions.
12 10 8
Results 6
4
As expected, none of the donation units or donor samples tested positive for HbS. All six of the known SCD patients showed a positive result using Sickledex. Full details are shown in Figures 3 and 4.
E e Cw 0 0 2 2 TRANSFUSION SCIENCE 6 6 4 4 2
Antigen negative Altered antigen
0 Partial antigen Conventional antigen 4 Discussion
A number of important mutations in these SCD patients were identified, including absence of U antigen, U variant and GATA-1 mutations. There were also partial antigens identified that had not been previously detected via standard serological methods. These findings are significant for donor and recipient transfusion purposes as they can lead to patients being immunised and can cause difficulties with the provision of blood for further transfusions.
Red cell genotyping for extended antigens makes transfusion safer for SCD patients by reducing the risk of immunisation through detection of numerous variants, distinction of autoantibodies from alloantibodies, and predicting clinical significance of antibodies for individual patient groups. This study confirms the importance of implementing extended genotyping into Northern Ireland to aid transfusion decisions along with improving bloodstock management by ensuring blood is prioritised, maintained and available for patients who require specific antigen-negative blood. This strategy will improve overall red cell usage. Future work based on a larger scale of donor/patient genotyping would be useful to study the clinical impact that RBC genotyping may have in patients with haemoglobinopathies. This could include monitoring alloimmunisation rates in these patients to justify Rh matching versus extended matching. It may also be worth considering other transfusion- dependent patient groups for genotyping strategies such as patients with aplastic anaemia, myelodysplastic syndrome or thalassaemia.
6
Number of patients
Number of patients
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57
