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Sadeghi bojd Y, Mirzaeyan F, Khooban Z, Oodi A. Molecular Resolution of ABO Discrepancies: A Case Series Involving Uncommon Weak B Subgroups. bloodj 2025; 22 (2) :168-174
URL: http://bloodjournal.ir/article-1-1582-en.html
Molecular Resolution of ABO Discrepancies: A Case Series Involving Uncommon Weak B Subgroups
Younes Sadeghi bojd , Fatemeh Mirzaeyan , Zahra Khooban , Arezoo Oodi *
Keywords: ABO Blood-Group System, Blood Group ABO Incompatibility, Blood Transfusion
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References:
  1. Kravchun PG, Korzh MO, Leontieva FS, Zinchenko OA, Lyzohub MV, Dielievska VY. Resolving Discrepancies in Forward and Reverse ABO Blood Group Typing. Scr Med 2023; 54(4): 425-37. [DOI:10.5937/scriptamed54-45572]
  2. Harmening DM, Forneris G, Tubby B. The ABO blood group system. In: Harmening DM.   Modern Blood Banking & Transfusion Practices. 6th ed. Philadelphia: FA Davis Company; 2012. p. 119-49.
  3. Qiu H, Wang X, Shao Y. Forward and reverse typing discrepancy and crossmatch incompatibility of ABO blood groups: cause analysis and treatment.  Hematology   2023;  28(1):    2240146. [DOI:10.1080/16078454.2023.2240146] [PMID]
  4. Cohn Claudia S, Delaney M, Johnson ST, Katz LM. Technical Manual. 20th ed. USA: AABB; 2020.
  5. Carson JL, Stanworth SJ, Guyatt G, Valentine S, Dennis J, Bakhtary S, et al. Red blood cell transfusion: 2023 AABB international guidelines. JAMA 2023; 330(19): 1892-902. [DOI:10.1001/jama.2023.12914] [PMID]
  6. Elardo E, Elbadri N, Sanchez C, Powell V, Smaris M, Li Y, et al. B subgroup detection in a small hospital transfusion service. Immunohematology 2021; 37(2): 89-94. [DOI:10.21307/immunohematology-2021-014] [PMID]
  7. Chaurasia R, Rout D, Dogra K, Coshic P, Chatterjee K. Discrepancy in Blood Grouping: Subgroups of B-Challenges and Dilemma. Indian J Hematol Blood Transfus 2017; 33: 628-9. [DOI:10.1007/s12288-017-0788-x] [PMID] []
  8. 8. Tiwari AK, Setya D, Arora D, Mehta SP, Aggarwal G, Mitra S. An algorithmic approach to serological work-up of ABO sub-groups which present as ABO discrepancies in resource constraint settings. J Immunol Methods 2020; 487: 112895. [DOI:10.1016/j.jim.2020.112895] [PMID]
  9. Jalali SF, Gudarzi S, Amirizadeh N, Mirzaeeian F, Oodi A. Analysis of ABO subgroups which result in ABO discrepancies in Iranian blood donors. Transfus Apher Sci 2023; 62(2): 103586. [DOI:10.1016/j.transci.2022.103586] [PMID]
  10. Khorshidfar M, Chegini A, Pourfathollah A, Oodi A, Amirizadeh N. Establishing blood group genotyping to resolve ABO discrepancies in Iran. Indian J Hematol Blood Transfus 2019; 35: 43-538. [DOI:10.1007/s12288-018-1044-8] [PMID] []
  11. Usmani A, Morris GP, Murphey C. The increasing need for ABO blood group genotyping and quality assurance implications for laboratory implementation. Hum Immunol 2024; 85(2): 110766. [DOI:10.1016/j.humimm.2024.110766] [PMID]
  12. Meny GM. Recognizing and resolving ABO discrepancies. Immunohematology 2017; 33(2): 76-81. [DOI:10.21307/immunohematology-2019-012]
  13. Gassner C, Schmarda A, Nussbaumer W, Schonitzer D. ABO glycosyltransferase genotyping by polymerase chain reaction using sequence-specific  primers.  Blood     1996; 88(5):
    1852-6. https://doi.org/10.1182/blood.V88.5.1852.1852 [    DOI:10.1182/blood.V88.5.1852.bloodjournal8851852]
  14. Dean L. Blood groups and red cell antigens; 2005. Available from: https://www. ncbi.nlm.nih. gov/books/ NBK2261/
  15. Harmening DM. Modern Blood Banking & Transfusion Practices. 5th ed. Philadelphia: FA Davis Company; 2018.
  16. Rahman MH, Islam MA, Khatun A, Rahman MA, Chowdhury TT, Saha M. ABO Blood Group Discrepancies Among The Recipients In A Tertiary Care Centre. Bangladesh Journal of Medicine 2025; 36(1): 43-9. [DOI:10.3329/bjm.v36i1.78397]
  17. Shahshahani HJ, Hayati A. Blood group discrepancies at a regional blood center. Int J Hematol Oncol Stem Cell Res 2020; 14(1): 38-44.
  18. Sharma T, Garg N, Singh B. ABO blood group discrepancies among blood donors in Regional Blood Transfusion Centre GTB Hospital, Delhi, India. Transfus Apher Sci 2014; 50(1): 75-80. [DOI:10.1016/j.transci.2013.11.002] [PMID]
  19. Thakral B, Saluja K, Bajpai M, Sharma RR, Marwaha N. Importance of weak ABO subgroups. Lab Med 2005; 36(1): 32-4. [DOI:10.1309/X59TAAYPEPCNBLUJ]
  20. Kaur G, Kaur P, Basu S, Kaur R. Blood group discrepancies at a tertiary care centre-analysis and resolution. Int Jo Lab Hematol 2014; 36(4): 481-7. [DOI:10.1111/ijlh.12176] [PMID]
  21. Makroo R, Chowdhry M, Bhatia A, Gupta R, Rosamma N, Phillip J. Two case reports of rare weak 'B'subgroup detected during routine testing. Apollo Medicine 2010; 7(3): 217-9. https://doi.org/10.1177/0976001620100312 [DOI:10.1016/S0976-0016(11)60109-9]
  22. Khan MN, Khan TA, Ahmed Z. Discrepancy in ABO blood grouping. J Coll Physicians Surg Pak 2013; 23(8): 590-2.
  23. Khatun A, Biswas J, Habibullah MM, Islam A, Shill N, Rahman A, et al. B subgroup: Bx blood group in a patient: A case report. Bangabandhu Sheikh Mujib Medical University Journal 2012; 5(1): 81-2. [DOI:10.3329/bsmmuj.v5i1.11032]
  24. Mohammadi S, Moghaddam M, Babahajian S, Karimian MS, Ferdowsi S. Discrepancy in ABO Blood Grouping in a Blood Donor: a case report. Iranian Journal of Blood and Cancer 2018; 10(2): 61-3.



Molecular Resolution of ABO Discrepancies: A Case
Series Involving Uncommon Weak B Subgroups


Younes Sadeghi-Bojd1        , Fatemeh Mirzaeyan1        , Zahra Khooban1, Arezoo Oodi1
 

1Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran

Received:  2025/04/21
Accepted: 2025/05/19
 





    https://doi.org/10.18502/avr.v34i2.18052

    


Citation:
Sadeghi-Bojd Y, Mirzaeyan F, Khooban Z, Oodi A. Molecular Resolution of ABO Discrepancies: A Case Series Involving Uncommon Weak B Subgroups. J Iran Blood Transfus. 2025: 22(1) : 168-174
    



Correspondence: Oodi A., Associate professor of Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine.
P.O.Box: 14665-1157, Tehran, Iran.
Tel: (+9821) 88601501-30
E-mail: a.oodi@tmi.ac.ir  		 A B S T R A C T
Background and Objectives
ABO grouping is one of the most important pre-transfusion test in blood banks, requiring concordance between forward (cell-type) and reverse (back-type) methods. ABO discrepancies arise when these two methods yield mismatched results, necessitating resolution to prevent adverse outcomes. A rare but significant cause of such discrepancies is the presence of weak B subgroups, characterized by markedly low B antigen expression. These subgroups are detected through the adsorption & elution method, which is very difficult and time-consuming. Molecular techniques offer a more accurate and efficient alternative for detecting these variants.  This study presents three uncommon cases of weak B subgroups, in which ABO grouping failed using serological methods and was clarified by molecular method.
Case Reports
Three patients samples were referred to the Immunohematology Reference Laboratory for ABO discrepancy analysis. The first case involved an 18-years-old female hospitalized for gastric surgery; the second, a 42-year old female undergoing cesarian section. In both cases, the packed RBC were requested and their mothers reported an O positive blood group. The third case was a 15-year-old mail with a mental disability whose sample was sent due to unresolved ABO grouping result. The cell-type and back-type ABO grouping was performed using both automated and tube methods. The results showed different discrepancies: cell-type grouping suggested weak B antigens, while the back-type grouping was consistent with group O. To resolve this incompatibility, Molecular testing was conducted using the PCR-SSP technique. The molecular results confirmed the presence of the B allele in all three cases. These molecular findings, integrated with serological results, support the classification of all patients as carriers of weak B subgroups.
Conclusions 
The Molecular methods serve as valuable complements to serological methods in accurately determining ABO blood groups in both donors and patients. Notably, ABO genotyping plays a critical role in confirming weak expression of A or B antigens, especially in cases where serological results are inconclusive.
Key words: ABO Blood-Group System, Blood Group ABO Incompatibility, Blood Transfusion
Copyright © 2025 Journal of Iranian Blood Transfusion, Published by Blood Transfusion Research Center.
This work is licensed under a Creative Common Attribution-Non Commercial 4.0 International license.




1- Acridine Orange
1- Biological safety cabinet
1- Platelet Concentrate
2- Food and Drug Administration
3- Normal Skin Flora
4- Platelet Rich Plasma-Platelet Concentrate
5- Eosin-Methylene blue
6- Thioglycolate
1- Acridine Orange
1- Biological safety cabinet
1- Platelet Concentrate
2- Food and Drug Administration
3- Normal Skin Flora
4- Platelet Rich Plasma-Platelet Concentrate
5- Eosin-Methylene blue
6- Thioglycolate

1- Acridine Orange
1- Biological safety cabinet
1- Platelet Concentrate
2- Food and Drug Administration
3- Normal Skin Flora
4- Platelet Rich Plasma-Platelet Concentrate
5- Eosin-Methylene blue
6- Thioglycolate
1- Acridine Orange
1- Biological safety cabinet
1- Platelet Concentrate
2- Food and Drug Administration
3- Normal Skin Flora
4- Platelet Rich Plasma-Platelet Concentrate
5- Eosin-Methylene blue
6- Thioglycolate


 
Type of Study: case report | Subject: Imunohematology
References
1. Kravchun PG, Korzh MO, Leontieva FS, Zinchenko OA, Lyzohub MV, Dielievska VY. Resolving Discrepancies in Forward and Reverse ABO Blood Group Typing. Scr Med 2023; 54(4): 425-37. [DOI:10.5937/scriptamed54-45572]
2. Harmening DM, Forneris G, Tubby B. The ABO blood group system. In: Harmening DM. Modern Blood Banking & Transfusion Practices. 6th ed. Philadelphia: FA Davis Company; 2012. p. 119-49.
3. Qiu H, Wang X, Shao Y. Forward and reverse typing discrepancy and crossmatch incompatibility of ABO blood groups: cause analysis and treatment. Hematology 2023; 28(1): 2240146. [DOI:10.1080/16078454.2023.2240146] [PMID]
4. Cohn Claudia S, Delaney M, Johnson ST, Katz LM. Technical Manual. 20th ed. USA: AABB; 2020.
5. Carson JL, Stanworth SJ, Guyatt G, Valentine S, Dennis J, Bakhtary S, et al. Red blood cell transfusion: 2023 AABB international guidelines. JAMA 2023; 330(19): 1892-902. [DOI:10.1001/jama.2023.12914] [PMID]
6. Elardo E, Elbadri N, Sanchez C, Powell V, Smaris M, Li Y, et al. B subgroup detection in a small hospital transfusion service. Immunohematology 2021; 37(2): 89-94. [DOI:10.21307/immunohematology-2021-014] [PMID]
7. Chaurasia R, Rout D, Dogra K, Coshic P, Chatterjee K. Discrepancy in Blood Grouping: Subgroups of B-Challenges and Dilemma. Indian J Hematol Blood Transfus 2017; 33: 628-9. [DOI:10.1007/s12288-017-0788-x] [PMID] []
8. Tiwari AK, Setya D, Arora D, Mehta SP, Aggarwal G, Mitra S. An algorithmic approach to serological work-up of ABO sub-groups which present as ABO discrepancies in resource constraint settings. J Immunol Methods 2020; 487: 112895. [DOI:10.1016/j.jim.2020.112895] [PMID]
9. Jalali SF, Gudarzi S, Amirizadeh N, Mirzaeeian F, Oodi A. Analysis of ABO subgroups which result in ABO discrepancies in Iranian blood donors. Transfus Apher Sci 2023; 62(2): 103586. [DOI:10.1016/j.transci.2022.103586] [PMID]
10. Khorshidfar M, Chegini A, Pourfathollah A, Oodi A, Amirizadeh N. Establishing blood group genotyping to resolve ABO discrepancies in Iran. Indian J Hematol Blood Transfus 2019; 35: 43-538. [DOI:10.1007/s12288-018-1044-8] [PMID] []
11. Usmani A, Morris GP, Murphey C. The increasing need for ABO blood group genotyping and quality assurance implications for laboratory implementation. Hum Immunol 2024; 85(2): 110766. [DOI:10.1016/j.humimm.2024.110766] [PMID]
12. Meny GM. Recognizing and resolving ABO discrepancies. Immunohematology 2017; 33(2): 76-81. [DOI:10.21307/immunohematology-2019-012]
13. Gassner C, Schmarda A, Nussbaumer W, Schonitzer D. ABO glycosyltransferase genotyping by polymerase chain reaction using sequence-specific primers. Blood 1996; 88(5): 1852-6. https://doi.org/10.1182/blood.V88.5.1852.1852 [DOI:10.1182/blood.V88.5.1852.bloodjournal8851852]
14. Dean L. Blood groups and red cell antigens; 2005. Available from: https://www. ncbi.nlm.nih. gov/books/ NBK2261/
15. Harmening DM. Modern Blood Banking & Transfusion Practices. 5th ed. Philadelphia: FA Davis Company; 2018.
16. Rahman MH, Islam MA, Khatun A, Rahman MA, Chowdhury TT, Saha M. ABO Blood Group Discrepancies Among The Recipients In A Tertiary Care Centre. Bangladesh Journal of Medicine 2025; 36(1): 43-9. [DOI:10.3329/bjm.v36i1.78397]
17. Shahshahani HJ, Hayati A. Blood group discrepancies at a regional blood center. Int J Hematol Oncol Stem Cell Res 2020; 14(1): 38-44.
18. Sharma T, Garg N, Singh B. ABO blood group discrepancies among blood donors in Regional Blood Transfusion Centre GTB Hospital, Delhi, India. Transfus Apher Sci 2014; 50(1): 75-80. [DOI:10.1016/j.transci.2013.11.002] [PMID]
19. Thakral B, Saluja K, Bajpai M, Sharma RR, Marwaha N. Importance of weak ABO subgroups. Lab Med 2005; 36(1): 32-4. [DOI:10.1309/X59TAAYPEPCNBLUJ]
20. Kaur G, Kaur P, Basu S, Kaur R. Blood group discrepancies at a tertiary care centre-analysis and resolution. Int Jo Lab Hematol 2014; 36(4): 481-7. [DOI:10.1111/ijlh.12176] [PMID]
21. Makroo R, Chowdhry M, Bhatia A, Gupta R, Rosamma N, Phillip J. Two case reports of rare weak 'B'subgroup detected during routine testing. Apollo Medicine 2010; 7(3): 217-9. https://doi.org/10.1177/0976001620100312 [DOI:10.1016/S0976-0016(11)60109-9]
22. Khan MN, Khan TA, Ahmed Z. Discrepancy in ABO blood grouping. J Coll Physicians Surg Pak 2013; 23(8): 590-2.
23. Khatun A, Biswas J, Habibullah MM, Islam A, Shill N, Rahman A, et al. B subgroup: Bx blood group in a patient: A case report. Bangabandhu Sheikh Mujib Medical University Journal 2012; 5(1): 81-2. [DOI:10.3329/bsmmuj.v5i1.11032]
24. Mohammadi S, Moghaddam M, Babahajian S, Karimian MS, Ferdowsi S. Discrepancy in ABO Blood Grouping in a Blood Donor: a case report. Iranian Journal of Blood and Cancer 2018; 10(2): 61-3.
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