Phenotype / Genotype for Blood Group Antigens

Clinical Background:

Request Reason: Investigation into Autoimmune Haemolytic Anaemia (AIHA) and sickle cell anaemia, preparation for multiple transfusions, preparation for bone marrow donation or as part of an antibody investigation profile. It is recommended that transfusion dependant patients (i.e Thalassemia syndromes, severe aplastic anaemia, sickle cell disease and other congenital or acquired anaemias) have an extended phenotype performed prior to any transfusions and that Rh and K compatible blood is used. Extended phenotype are also performed on patients who have newly identified alloantibodies and/or non-specific/auto antibodies and are expected to receive numerous transfusions (i.e. Haematology, PBSC Donors, Oncology, Solid Organ Transplant, Renal and Multi-Transfused patients). Phenotype investigations as required to determine the antigens carried on a red blood cell (RBC). The "phenotype" of any blood group refers to which antigens are serologically detectable on the RBC, and usually (though not always) corresponds to the genes that the patient carries. The test procedure is based on the principle of agglutination. Normal human red cell, processing antigens, will agglutinate in the presence of antibody directed toward the antigen. Rh phenotyping tests for the D, C, E, c, e and K antigens. Extended phenotyping tests for the D, C, E, c, e, K, Jka, Jkb, Fya, Fyb and MNSs antigens. Molecular genotyping refers to the detection of the molecular basis of an antigen, rather than the antigen itself. Molecular testing can be used to replace serologic typing in cases where it is not possible to serologically identify the antigen, e.g. following chronic or massive transfusions, where donation red blood cells (RBCs) makes typing inaccurate, autoimmune haemolytic anaemia or where RBC’s are coated with immunoglobulin, the presence of bound IgG often invalidates typing results in the indirect antiglobulin test (IAT). Molecular DNA-based methods overcome these limitations. Molecular Genotype tests, where required, will be referred by the blood transfusion laboratory to the NHSBT – Newcastle reference centre. Molecular genotyping tests for selected RHCE variants, selected RHD variants and genes coding for K, k, Jsa, Jsb, Kpa, Kpb, Fya, Fyb, Fy(GATA), Jka, Jkb, MNSs, U, Doa, Dob.

Discipline:

Transfusion

Transfusion
Specimen Container Adult:

6mL K2 EDTA (Pink Top)

6mL K2 EDTA (Pink Top)
Specimen Container Paediatric:

0.5mL K2 EDTA (Pink Top) or 6mL K2 EDTA (Pink Top)

0.5mL K2 EDTA (Pink Top) or 6mL K2 EDTA (Pink Top)
Minimum Volume Adult:

6mL

6mL
Minimum Volume Paediatric:

0.5mL

0.5mL
Special Requirement:

Sample must be HANDWRITTEN and contain the patient's details.

Sample must be HANDWRITTEN and contain the patient's details.
Sample Stability:

Short term storage: 24 hours at Room Temperature. Long term storage: 7 days at 4-6

Short term storage: 24 hours at Room Temperature. Long term storage: 7 days at 4-6
Transport Requirements:

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot...

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot or cold conditions prior to testing.
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Add On Test:

All urgent add ons via telephone must be confirmed via email to the appropriate email address

tnu-tr.bloodsciencesadditions@nhs.net (internal)

tnu-tr.bloodsciencesadditions@nhs.net (external)

All urgent add ons via telephone must be confirmed via email to the appropriate email address

tnu-tr.bloodsciencesadditions@nhs.net (internal)

tnu-tr.bloodsciencesadditions@nhs.net (external)
Interpretation:

The presence or absence of antigens and antibodies is identified by agglutination. Agglutination occurs when the red cells are cross-linked by the binding of either IgG or IgM antibody molecules. T...

The presence or absence of antigens and antibodies is identified by agglutination. Agglutination occurs when the red cells are cross-linked by the binding of either IgG or IgM antibody molecules. The pattern of reactions against a panel of reagents with known antigen or antibody status is used to identify the antibodies or antigens present. The report will state the patient’s Blood Group and indicate whether alloantibodies are present or not. The blood group antigens reported will show whether the patient is positive (demonstrates the antigen) or negative for the antigen type.
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Factors Affecting Result:

Key factors affecting the result: • Incorrect specimen type received • Clotted, haemolysed, icteric or lipaemic samples • Clotted samples may interfere with instrument pipetting and must not be use...

Key factors affecting the result: • Incorrect specimen type received • Clotted, haemolysed, icteric or lipaemic samples • Clotted samples may interfere with instrument pipetting and must not be used. • Fibrin or particulate matter, clots, bubbles or scratches can interfere with reaction interpretations.
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Referenced Documents:

4/1/15

4/1/15
Routine Contact Name:

Section Leader:
Routine Telephone:

Freeman: 0191 213 7849
RVI: 0191 282 4335

Freeman: 0191 213 7849
RVI: 0191 282 4335
Specialist Test:

Yes

Yes
Specialist Contact Name:

transfusion manager

transfusion manager
Specialist Telephone:

0192 213 9169

0192 213 9169

Phenotype / Genotype for Blood Group Antigens

Clinical Background:

Test Details

Availability:

Turn Around: