Retatrutide Pharmacogenetics: Triple Agonist Genetics (Investigational)
Retatrutide is still investigational, but two receptor variants already characterized in approved drugs are expected to carry over. A third, in the glucagon receptor, remains an open question.
Reviewed by the Gene2Rx team. Updated 2026-05-28.
Looking for a different angle? Which GLP-1 is right for me?
Retatrutide (Eli Lilly, development code LY3437943) is an investigational triple agonist that hits three receptors at once: GLP-1, GIP, and glucagon. Phase 2 trial data showed about 24 percent body weight loss at 48 weeks, beyond what any approved incretin agent has produced. The drug is in phase 3 trials and not yet FDA-approved.
Why pharmacogenetics applies to retatrutide
Why a third receptor matters
Glucagon receptor activation increases energy expenditure. That complements the appetite-reducing effects of GLP-1 and GIP activation. The combination drives the larger weight loss seen in trials.
Why pharmacogenetic data is preliminary
Most retatrutide pharmacogenetic guidance is extrapolated from semaglutide and tirzepatide research, since those drugs share the GLP-1 and GIP arms. Direct retatrutide pharmacogenetic data should come as the phase 3 program reads out.
How your genetics can play a role
Three genes encode the three receptors retatrutide activates. Two have well-characterized pharmacogenetic signals from related drugs. The third is still an open question. There are no established dosing guidelines specific to retatrutide,[2] and the gene-response associations below are extrapolated from approved agents.
| Gene | What it affects |
|---|---|
| GLP1R | The Pro7Leu variant (rs10305420) affects all GLP-1 agonists, retatrutide included. Leu7 carriers are expected to see slightly greater weight loss and modestly higher nausea risk from the GLP-1 arm of retatrutide. |
| GIPR | The Gln354 variant (rs1800437) reduces GIP-receptor function. By analogy with tirzepatide, Gln354 carriers likely have higher GI side-effect risk on retatrutide. Direct retatrutide data is not yet available. |
| GCGR | The glucagon receptor adds the third arm of activity. So far, no common GCGR variant has been shown to substantially alter retatrutide response in published data. This is an active research area. |
The strongest pharmacogenetic signal expected for retatrutide is the GIPR Gln354 effect on GI side effects. The GLP1R signal-peptide effect should also carry over. The GCGR component adds weight loss beyond what dual agonists achieve, but no actionable common variant has been identified for it yet.
Retatrutide is still investigational, but the GLP1R and GIPR variants its response is expected to hinge on are readable in your DNA today. Find out which ones you carry.
A Gene2Rx report reads your own DNA to show how it may affect your response to Retatrutide and your other medications.
When to consider pharmacogenetic testing
Most relevant if you are in a retatrutide trial or thinking about joining one, or if you are weighing whether GIPR-mediated nausea on tirzepatide makes retatrutide a poor fit once it becomes available.
What you can do next
- If you are in a retatrutide trial, share your GIPR genotype with your study team. Trial protocols will not adjust dose based on genetics, but the information helps set expectations.
- If you have struggled with tirzepatide nausea and you carry the GIPR variant, expect the same effect on retatrutide once it is approved.
- Keep an eye on the literature. As phase 3 results are published, retatrutide-specific pharmacogenetic data will become available.
How your genetics shape your GLP-1 response
A GLP1R variant is associated with how much weight people lose, and a GIPR variant with nausea and vomiting risk on tirzepatide. Our GLP-1 guide walks through what each result means.
Read the GLP-1 genetics guideRelated medications
See how genetics may affect your response to Retatrutide, Semaglutide, Tirzepatide.
Related guides
- Tirzepatide (Mounjaro, Zepbound) Not Working: GLP1R and GIPR Genetics
- Which GLP-1 Is Right for Me?
- Why Isn't Ozempic or Wegovy Working for Me? The GLP1R Connection
- 23andMe Drug Response: What You'll Actually See in a Report From Your Data
- 23andMe Pharmacogenetics: How to Get a Drug Response Report From Your Existing Data
- AncestryDNA for Drug Testing: Get Pharmacogenetics From Your Ancestry Data
Frequently asked questions
When will retatrutide be available?
Lilly expects to file for FDA approval based on the ongoing phase 3 program. The timing depends on trial readouts and FDA review. Until approval, the drug is available only through clinical trials.
Will retatrutide be better than tirzepatide?
Phase 2 data showed greater weight loss for retatrutide than tirzepatide at the highest doses. The phase 3 data will be more definitive, but the early signal is positive.
Will retatrutide have new pharmacogenetic concerns from the glucagon arm?
Possibly, though so far no common GCGR variant has been linked to a meaningful clinical difference. The glucagon arm raises energy expenditure, and theoretical effects on baseline glucose handling are being watched in trials.
References
- Nature / 23andMe Research Institute. Su QJ, et al. Genetic predictors of GLP1 receptor agonist weight loss and side effects. Nature 653:770-775 (2026). nature.com
- PharmGKB / Stanford University. PharmGKB: The Pharmacogenomics Knowledge Base. pharmgkb.org
Disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider before making changes to your medication. Never stop or change a medication without medical supervision.