HPA-1a (PLA1 Platelet Antigen) Genotyping (PLA2 Polymorphism Detection)

CPT: 81105
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Test Details


  • PLA2 Polymorphism Detection


Individuals negative for the HPA-1a (PLA1) antigen are at risk for developing antibodies to this antigen as may occur in neonatal alloimmune thrombocytopenia and post-transfusion purpura.


Amplification refraction mutation system (ARMS) polymerase chain reaction (PCR)

Additional Information

This is a molecular test to genotype the HPA-1 DNA sequence. The wild-type platelet glycoprotein HPA-1a (PLA1) is present in approximately 98% of the general population. A single nucleotide polymorphism changes the antigenic determinant from HLA-1a (PLA1) to HPA-1b (PLA2). Alloimmune platelet-associated immunoglobulin (PAIg) antibodies arise when there is an antigenic challenge to individuals who lack specific platelet antigens. Neonatal alloimmune thrombocytopenia is a serious, potentially fatal disease affecting fetuses and neonates. Fetal expression of platelet antibodies foreign to the mother result in maternal formation of antiplatelet antibodies with subsequent destruction of fetal platelets. Approximately 80% of these antibodies form in neonatal alloimmune thrombocytopenia anti-HPA-1a (PLA1). This same antibody is implicated in cases of post-transfusion purpura, in which the recipient of a platelet-containing blood product develops antiplatelet antigens that destroy not only the transfused platelet, but native platelets as well. The mechanism of this destruction is poorly understood.

Specimen Requirements


Whole blood


5 mL


Blue-top (sodium citrate) tube, lavender-top (EDTA) tube, or yellow-top (ACD) tube

Storage Instructions

Maintain specimen at room temperature. Stable at room temperature or refrigerated for eight days.

Clinical Information

Special Instructions

Informed consent is required for New York patients.


Adcock DM, Bethel MA, Macy PA. Coagulation Handbook. Aurora, Colo: Esoterix−Colorado Coagulation; 2006.
Friedberg RC, Donnelly SF, Mintz PD. Independent roles for platelet crossmatching and HLA in the selection of platelets for alloimmunized patients. Transfusion. 1994; 34(3):215-220. 8146893
8123835. Newman PJ. Nomenclature of human platelet alloantigens: A problem with the HPA system? Blood. 1994; 83(6):1447-1451.
Nugent DJ. Alloimmunization to platelet antigens. Semin Hematol. 1992; 29(3 Suppl 2):83-88. 1509298


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
500314 HPA-1a (PLA1 Plt Ag) Genotyp. 501703 HPA-1a Geno (PLA2 Poly. Det.) N/A
500314 HPA-1a (PLA1 Plt Ag) Genotyp. 500315 Results 50599-0
500314 HPA-1a (PLA1 Plt Ag) Genotyp. 500316 Interpretation 69049-5
500314 HPA-1a (PLA1 Plt Ag) Genotyp. 500317 Comments 8251-1

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