Human Platelet Antigen 1 genotyping (HPA-1), ITGB3 (integrin, beta 3 [platelet glycoprotein IIIa], antigen CD61 [GPIIIa]) (eg, neonatal alloimmune thrombocytopenia [NAIT], post-transfusion purpura), gene analysis, common variant, HPA-1a/b (L33P)
CPT4 code
Name of the Procedure:
Human Platelet Antigen 1 genotyping (HPA-1), ITGB3 (integrin, beta 3 [platelet glycoprotein IIIa], antigen CD61 [GPIIIa]) gene analysis, common variant, HPA-1a/b (L33P)
Summary
Human Platelet Antigen 1 (HPA-1) genotyping is a genetic test used to identify specific variants of the ITGB3 gene. This test helps determine whether an individual has HPA-1a or HPA-1b alleles, which can be important in diagnosing conditions like neonatal alloimmune thrombocytopenia (NAIT) and post-transfusion purpura.
Purpose
This procedure addresses conditions related to platelet compatibility issues. It aims to prevent and manage immune responses caused by platelet antigen mismatches, particularly in neonates and post-transfusion patients. By identifying the HPA-1 genotype, healthcare providers can better manage and treat affected individuals.
Indications
- Symptoms of neonatal alloimmune thrombocytopenia (NAIT)
- Cases of post-transfusion purpura
- Pregnancies at risk for NAIT due to maternal-fetal platelet antigen mismatch
- Patients with a history of unexplained platelet refractoriness
Preparation
No special preparation is typically required for HPA-1 genotyping. Patients may need to provide a blood sample, and it is essential to inform healthcare providers of any medications being taken.
Procedure Description
- Sample Collection: A blood sample is collected from the patient, usually from a vein in the arm.
- DNA Extraction: DNA is extracted from the blood sample in a laboratory.
- Genotyping: The extracted DNA is analyzed to identify the specific variant of the ITGB3 gene (HPA-1a or HPA-1b).
- Reporting: Results are interpreted and reported to the healthcare provider, who will discuss them with the patient.
This procedure typically uses specialized genetic testing equipment and does not involve anesthesia or sedation.
Duration
The procedure itself, including sample collection, takes a few minutes. However, analyzing the DNA and obtaining results may take several days to a few weeks.
Setting
The blood sample is collected in a healthcare setting such as a hospital, clinic, or lab, and the genetic analysis is performed in a specialized laboratory.
Personnel
- Phlebotomist or nurse (for blood sample collection)
- Laboratory technicians and geneticists (for DNA analysis and interpretation)
Risks and Complications
- Minimal risks associated with blood sample collection, such as slight pain or bruising at the puncture site
- Rare risk of infection at the puncture site
Benefits
- Accurate identification of HPA-1 genotype
- Improved management and treatment of conditions like NAIT and post-transfusion purpura
- Enhanced outcomes for affected neonates and transfusion patients
Recovery
There is no significant recovery time required post-procedure. Patients can resume normal activities immediately after the blood sample is collected.
Alternatives
- Detailed hematological assessments
- Other platelet antigen genotyping tests (if available)
- Serological testing for platelet antibodies
These alternatives may vary in accuracy and specificity compared to HPA-1 genotyping.
Patient Experience
During the procedure, patients might feel a slight pinch or discomfort when the blood sample is taken. Post-procedure, there are no specific experiences, as the genetic testing is performed in the lab without further patient involvement. Pain management is typically unnecessary.