CPT® Code 81112

Human Platelet Antigen 15 genotyping (HPA-15), CD109 (CD109 molecule) (eg, neonatal alloimmune thrombocytopenia [NAIT], post-transfusion purpura), gene analysis, common variant, HPA-15a/b (S682Y)

The CPT® Code 81112 refers to the gene analysis for Human Platelet Antigen 15 (HPA-15) genotyping, specifically focusing on the common variant HPA-15a/b, which is associated with certain medical conditions such as neonatal alloimmune thrombocytopenia (NAIT) and post-transfusion purpura. This procedure involves the identification of specific genetic variants that can impact platelet function and immune response. The HPA-15 gene encodes for a protein known as CD109, which is a molecule found on the surface of platelets. Variants in this gene can lead to the development of platelet alloantigens, which occur due to single nucleotide polymorphisms (SNPs) that alter the genes coding for platelet membrane glycoproteins. The analysis is particularly significant in clinical scenarios involving symptomatic neonates, where it can help identify HPA-15 variants that may contribute to NAIT, a condition where maternal antibodies target fetal platelets, leading to severe thrombocytopenia and potential complications such as intracranial hemorrhage. Additionally, this test can be utilized during pregnancy to screen for fetal alloimmunization and assess the risk of NAIT in future pregnancies, as well as to evaluate the risk of post-transfusion purpura in women who have received platelet transfusions containing incompatible HPA or platelet-specific antigens. The testing process typically involves obtaining samples from blood, amniotic fluid, or cultured amniocytes, which are then analyzed using multiplex polymerase chain reaction (PCR) techniques to detect the presence of specific alleles associated with the HPA-15 variant.