Genotyping of HLA-A or HLA-B
HLA-A and HLA-B (major histocompatibility complex, class I, A, and B) are closely related proteins in the human leukocyte antigen (HLA) complex. They play important roles in the immune system and are found in almost all cells.
Carriers of certain polymorphisms, such as HLA-A * 31: 01, HLA-B * 15: 02, HLA-B * 57: 01 rs2395029 (LD), and HLA-B * 58: 01, are at risk of severe hypersensitivity when administering certain medications, including abacavir (Ziagen), allopurinol (Zyloprim), phenytoin (Dilantin), and carbamazepine (Tegretol). These drugs are generally used as part of treatments for epilepsy, bipolar disorder, gout, and HIV.
Indications for HLA-A and HLA-B tests
Pre-initiation testing of drugs that have a common impact helps to identify patients at high risk for serious drug-induced hypersensitivity reactions. Testing should be considered for people with a personal or family history of adverse effects of the drugs abacavir (Ziagen), allopurinol (Zyloprim), and carbamazepine (Tegretol). Tests should be done to confirm the presence of genotypes that affect sensitivity to specific drugs.
Patients initiating carbamazepine may benefit from the HLA-A * 3101 test. All patients of Asian ethnicity should be tested for the HLA-B * 15: 02 allele prior to phenytoin (Dilantin) and carbamazepine (Tegretol) and administration of fosphenytoin (Cerebyx). Patients of all ethnicities should be screened for HLA-B * 57: 01 rs2395029 (LD) prior to administration of abacavir due to the incidence of hypersensitivity. All patients should be screened for HLA-B * 58: 01 prior to allopurinol therapy due to severe skin reactions. Assessment of the medical necessity of testing is based on the provider’s clinical judgment.
Insurance coverage, special order
HLA-B * 57: 01 rs2395029 (LD) testing may be covered by private insurance providers (CPT code 81381, provided as a guide only). HLA-A * 31: 01, HLA-B * 15: 02 and HLA-B * 58: 01 are only available as special order projects (contact us for pricing).
- Buccal swabs: 4 sterile buccal swabs
- Blood: 5-10 cc whole blood with EDTA with a lavender top or ACD-A tubes with a yellow top
- Turnaround time: 10 business days, faster availability for clinical trials