Platelet antigen genotyping

Keywords: Platelet antigen typing

Specimen:

10 mL ACD or EDTA.

Paediatrics - 3 mL EDTA.

Can use buccal swabs, especially for neonates; and Chorionic Villous Sampling (CVS) or amniotic fluid for in utero investigations.

Method:

PCR-SSP (sequence-specific primer). Antigen expression tests are done by platelet immunofluorescence test (PIFT), if required.

Application:

Investigation of alloimmune thrombocytopenia, especially neonatal alloimmune thrombocytopenia and post-transfusion purpura.

Interpretation:

Demonstrates allelic variation of genes coding for human platelet antigens (HPAs).

Patients can form alloantibodies to antigens coded by alleles they do not themselves possess. Antigen-negative platelets can be selected for transfusion to such patients. In cases of Fetomaternal alloimmune thrombocytopenia, prophylactic antenatal treatment can be instituted.

Very specialised area - consult pathologist.

Reference:

Lochowitz AJ et al. LabMedicine 2011; 42: 687-692.

Curtis BR et al. Immunohematology 2009; 25: 125-135.