Interferon Lambda 3 (formerly IL28B)
IFNL3 produces a type III interferon that helps the immune system clear viral infections. A variant in the gene's regulatory region (rs12979860) was, for a long time, the strongest known predictor of who would clear chronic hepatitis C on the old interferon-plus-ribavirin regimen. C/C carriers had roughly double the cure rate of T/T carriers.
Gene2Rx reports your IFNL3 genotype across 2 named alleles, built from 1 variant curated by PharmVar.
IFNL3 alleles are named by the underlying DNA variant rather than a star number — for example c.61C>T describes a single base change at position 61 of the coding sequence.
You inherit one allele from each parent, and the pair determines whether your IFNL3 activity is normal, decreased, or absent.
PharmVar is the international registry that curates these names. Gene2Rx tests every variant needed to call each cataloged IFNL3 allele.
Gene2Rx covers 3 medications with published pharmacogenetic guidance for IFNL3, drawn from CPIC and FDA sources. Each drug links to its full pharmacogenetics page.
These branded medications include at least one active ingredient whose metabolism or action involves IFNL3. Each links to its full pharmacogenetic breakdown.
This page lists drugs affected by IFNL3. A Gene2Rx report tells you which metabolizer group you fall into, and what that means for every medication on this list.
Get your report Look up a medicationInformational only, not medical advice. The presence of a IFNL3 pharmacogenetic guideline does not mean every patient needs to change their dose. Never start, stop, or change a medication without talking to your prescribing clinician.