GRIK4 Genotyping
GRIK4 (glutamate receptor, ionotropic, kainate 4) is the gene that encodes KA1, a type of neurotransmitter receptor subunit that joins together with other subunits to form a glutamate receptor. These receptors are located on cells in the brain and are involved in enhancing cell-cell communication, which may play a role in major depressive disorder. This type of receptor primarily binds glutamate, a major neurotransmitter involved in developmental growth, learning and memory. Although the effect of variations in GRIK4 on KA1 function and expression are not fully known, KA1 may play a role in modulating the therapeutic effect of antidepressants. Mutations in GRIK4 may impact patients with major depressive disorder who take citalopram (Celexa®).[49] Genetic variant tested for GRIK4 is c.83-10039T>C.
Indications for GRIK4 Testing
Patients being considered for citalopram or who have experienced treatment resistance or failure with citalopram should be considered for GRIK4 testing. Assessment of medical necessity for testing is ultimately up to the provider’s clinical judgment. More clinical evidence is needed to determine the range of drugs and psychiatric conditions affected by GRIK4 polymorphisms.
Insurance Coverage
Check with your insurance provider to see if GRIK4 is covered. The CPT code for GRIK4 testing is 81479 (provided as guidance only).
Specimen Collection
Click here to order testing supplies or call Client Services at 800-837-8362.
- Buccal Swabs: 4 sterile buccal swabs
- Blood: 5-10cc whole blood lavender-top EDTA or yellow-top ACD-A tubes
- Turnaround Time: 10 business days, faster turnaround available for clinical trials