Table 1

Clinically most relevant human platelet alloantigen (HPA) systems associated with neonatal alloimmune thrombocytopenia

System Antigen Alternative names Glycoprotein Nucleotide change Amino acid change
HPA-1HPA-1aZwa, plA1 GPIIIaT196 Leucine33
HPA-1bZwb, plA2 C196 Proline33
HPA-2HPA-2aKob GPIbαC524 Threonine145
HPA-2bKoa, Siba T524 Methionine145
HPA-3HPA-3aBaka, Leka GPIIbT2622 Isoleucine843
HPA-3bBakb G2622 Serine843
HPA-41-150 HPA-4aYukb, Pena GPIIIaG526 Arginine143
HPA-4bYuka, Penb A526 Glutamine143
HPA-5HPA-5aBrb, Zavb GPIaG1648 Glutamic acid505
HPA-5bBra, Zava, Hca A1648 Lysine505
  • 1-150 Not important in the white population because the mutation has only been detected in populations from the Far East.