CPT® Code 81107

Official Description

Human Platelet Antigen 3 genotyping (HPA-3), ITGA2B (integrin, alpha 2b [platelet glycoprotein IIb of IIb/IIIa complex], antigen CD41 [GPIIb]) (eg, neonatal alloimmune thrombocytopenia [NAIT], post-transfusion purpura), gene analysis, common variant, HPA-3a/b (I843S)

Common Language Description

The CPT® Code 81107 refers to the gene analysis for Human Platelet Antigen 3 (HPA-3) genotyping, specifically targeting the ITGA2B gene, which encodes the integrin alpha 2b, a component of the platelet glycoprotein IIb/IIIa complex. This analysis is crucial for identifying the HPA-3a/b allele variants that are associated with conditions such as neonatal alloimmune thrombocytopenia (NAIT) and post-transfusion purpura. NAIT is a serious condition that arises when maternal IgG antibodies cross the placenta and attack the paternally derived alloantigens present on fetal platelets, leading to severe thrombocytopenia and potential complications such as intracranial hemorrhage. Post-transfusion purpura, on the other hand, occurs when a woman receives a platelet transfusion that contains incompatible HPA or platelet-specific antigens, resulting in severe bleeding episodes typically occurring 5 to 10 days post-transfusion. The identification of HPA-3 variants is particularly significant as these variants are found in approximately 1% of cases involving NAIT and post-transfusion purpura. The testing process involves obtaining samples from blood, amniotic fluid, or cultured amniocytes, which are then analyzed using multiplex polymerase chain reaction (PCR) techniques to detect the specific allele variants through fluorescence observation. This gene analysis not only aids in diagnosing symptomatic neonates but also plays a vital role in screening for fetal alloimmunization during pregnancy and assessing the maternal risk for NAIT in future pregnancies or post-transfusion complications.

1. Indications

The Human Platelet Antigen 3 genotyping (HPA-3) test is indicated for several specific clinical scenarios, particularly related to conditions that affect platelet function and immune response. The following are the primary indications for performing this gene analysis:

Neonatal Alloimmune Thrombocytopenia (NAIT) - This condition occurs when maternal antibodies target fetal platelets, leading to severe thrombocytopenia and potential complications such as intracranial hemorrhage.
Post-Transfusion Purpura - This condition arises when a woman receives a platelet transfusion containing incompatible HPA or platelet-specific antigens, resulting in severe bleeding episodes occurring 5 to 10 days after the transfusion.
Fetal Alloimmunization Screening - The test may be used to screen for fetal alloimmunization during pregnancy, helping to identify at-risk pregnancies.
Maternal Risk Assessment - The analysis assists in assessing the risk for NAIT in future pregnancies or the risk of post-transfusion purpura in women with a history of these conditions.

2. Procedure

The procedure for Human Platelet Antigen 3 genotyping involves several key steps to ensure accurate identification of the HPA-3a/b allele variants. The following outlines the procedural steps:

Sample Collection - Blood, amniotic fluid, or cultured amniocytes are collected as the source material for testing. This collection is performed through a separately reportable procedure, ensuring that the samples are obtained in a sterile and appropriate manner.
DNA Extraction - Once the samples are collected, DNA is extracted from the cells present in the blood or amniotic fluid. This step is crucial for isolating the genetic material needed for analysis.
Multiplex Polymerase Chain Reaction (PCR) - The extracted DNA undergoes multiplex PCR, a technique that allows for the amplification of specific DNA sequences associated with the HPA-3 gene. This method utilizes allele-specific primer extensions to target the HPA-3a/b variants.
Fluorescence Observation - After amplification, the PCR products are analyzed using fluorescence observation. This step enables the detection of the specific allele variants present in the sample, confirming the presence of HPA-3a or HPA-3b alleles.

3. Post-Procedure

Post-procedure care following the Human Platelet Antigen 3 genotyping is generally minimal, as the procedure primarily involves laboratory analysis rather than invasive techniques. However, it is essential to monitor the patient for any potential complications related to the sample collection, such as bleeding or infection at the site of blood draw or amniocentesis. Results from the gene analysis will typically be available within a specified timeframe, allowing for timely clinical decision-making regarding the management of NAIT or post-transfusion purpura. Healthcare providers should ensure that patients are informed about the results and any necessary follow-up actions, particularly in the context of future pregnancies or transfusion needs.

Short Descr	HPA-3 GENOTYPING
Medium Descr	HPA-3 GENOTYPING GENE ANALYSIS COMMON VARIANT
Long Descr	Human Platelet Antigen 3 genotyping (HPA-3), ITGA2B (integrin, alpha 2b [platelet glycoprotein IIb of IIb/IIIa complex], antigen CD41 [GPIIb]) (eg, neonatal alloimmune thrombocytopenia [NAIT], post-transfusion purpura), gene analysis, common variant, HPA-3a/b (I843S)
Status Code	Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days	XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC)	9 - Not Applicable
Multiple Procedures (51)	9 - Concept does not apply.
Bilateral Surgery (50)	9 - Concept does not apply.
Physician Supervisions	09 - Concept does not apply.
Assistant Surgeon (80, 82)	9 - Concept does not apply.
Co-Surgeons (62)	9 - Concept does not apply.
Team Surgery (66)	9 - Concept does not apply.
Diagnostic Imaging Family	99 - Concept Does Not Apply
CLIA Waived (QW)	No
APC Status Indicator	Service Paid under Fee Schedule or Payment System other than OPPS
Type of Service (TOS)	5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS)	none
MUE	1

90	Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.