IFNL3 (IL28B) Genotyping

The IFNL3 (IL28B) gene encodes for the protein interferon lambda 3, a cytokine, which has antiviral, antiproliferative and immune-modulatory properties. Cytokines are released in the presence of viruses, bacteria or tumor cells. IFNL3 polymorphisms may indicate either a favorable or unfavorable response to treatment of Hepatitis C Virus (HCV) Genotype 1, the most common type of HCV in the U.S., with pegylated interferon-alfa and ribavirin containing regimens. While IFNL3 genotyping is a strong predictor of treatment response, it does not determine whether or not to treat HCV infection.


Indications for Testing

IFNL3 testing may be beneficial for HCV genotype 1 patients to help predict response to pegylated interferon-alfa and ribavirin containing treatment regimens. However, while IFNL3 genetic testing may be prognostically useful, the clinical utility of testing is still unclear because results alone do not change current HCV treatment recommendations. There may be a limited role for IFNL3 testing in decreasing treatment durations or selecting double versus triple therapy regimens, but more research in this area is needed.


Insurance Information

IFNL3 testing is currently not covered by Medicare. Private insurance coverage varies by insurance company. The CPT code for IFNL3 testing is 81400 (provided for your guidance only).

Specimen Information

  • Buccal Swabs: 4 sterile buccal swabs
  • Blood: 5-10cc whole blood lavender-top EDTA or yellow-top ACD-A tubes

Turnaround Time: 7 business days, faster turnaround available for clinical trials