Overview
The Duffy blood group system comprises red-cell protein antigens Fya and Fyb (and related specificities); alloantibodies are typically warm-reactive IgG antibodies whose panel reactivity is characteristically abolished by proteolytic enzyme treatment of test cells.
Classification
| Phenotype | Antigens | Antibody risk framing |
|---|---|---|
| Fy(a+b−) | Fya | May form anti-Fyb |
| Fy(a−b+) | Fyb | May form anti-Fya |
| Fy(a+b+) | Both | Neither anti-Fya nor anti-Fyb typically |
| Fy(a−b−) | Neither | May form anti-Fya, anti-Fyb, and/or anti-Fy3 |
Morphologic Features
Not a cell-morphology topic. Serologic endpoints on screen/panel; phenotype with anti-Fya/anti-Fyb reagents.
Laboratory Characteristics
- AHG detection on untreated screening/panel cells
- Enzyme panel often nonreactive for Duffy antibodies
- Patient Duffy phenotype when typing is valid
- Antigen-negative RBC procurement after ID
Reference Intervals
Categorical phenotypes and antibody interpretations, no numeric reference intervals. Matching extent beyond identified antibodies (e.g., extended phenotype protocols) is institutional policy.
Clinical and Laboratory Significance
Duffy alloantibodies can mediate hemolytic transfusion reactions and HDFN risk; antigen-negative RBC selection after identification is the core laboratory control.
Differential Considerations
Enzyme-sensitive pattern: Duffy vs MNS vs other sensitive specificities, resolve with untreated antigen distribution and phenotype. Distinguish alloanti-Fya from warm autoantibody with careful auto-control and elution pathways per SOP when indicated.
Comparison Tables
Enzyme panel educational contrast
| System | Typical enzyme effect | Significance framing |
|---|---|---|
| Duffy | Destroyed / reactivity lost | Usually significant |
| MNS (M/N) | Often destroyed | Variable, see MNS lesson |
| Kidd | Often enhanced / persists | Usually significant; evanescence risk |
| Rh | Often enhanced / persists | Usually significant |
Classification Frameworks
Not applicable, blood group system (ISBT FY), not a WHO disease classification.
Laboratory Notes
- Do not equate ancestry with phenotype, type the patient
- Enzyme clues support ID; untreated rule-outs confirm it
- Fy(a−b−) with anti-Fy3 needs early specialized support
References
Authoritative textbooks, guidelines, and reviews supporting this reference entry. Verify reference intervals, critical limits, and reflex criteria against institutional protocols and current guideline editions.
Textbooks
- Cohn CS, Delaney M, Johnson ST, Katz LM, eds. Technical Manual. 21st ed. AABB; 2023.
- Harmening DM. Modern Blood Banking & Transfusion Practices. 7th ed. F.A. Davis; 2019.
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
CLSI and Professional Guidelines
- AABB. Standards for Blood Banks and Transfusion Services (verify current edition and institutional adoption).
- U.S. Food and Drug Administration. Code of Federal Regulations Title 21 . Blood and Blood Components (verify current institutional adoption).
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