First Genomic Study of CHS Found Genetic Mutations That May Explain Who Gets It | Research

The takeaway

The first genomic investigation of CHS found that patients carried significantly more mutations in genes affecting cannabinoid metabolism (CYP2C9), pain perception (TRPV1), dopamine signaling (DRD2), and other pathways compared to cannabis-using controls.

Gastroenterologists; emergency physicians diagnosing CHS; genetics researchers; cannabis users experiencing unexplained vomiting.

COMT mutation 12x more common in CHS patients vs cannabis-using controls

What the researchers found

CHS patients showed significantly elevated mutations in COMT (OR 12.0), ABCA1 (OR 8.4), CYP2C9 (OR 7.8), DRD2 (OR 6.2), and TRPV1 (OR 5.8) compared to cannabis-using controls without CHS. 87.7% of patients improved with cannabis cessation, but most relapsed rapidly after resumption.

Why it matters

CHS affects some heavy cannabis users but not others. This study provides the first genetic evidence explaining this selective vulnerability, pointing to specific metabolic and receptor genes that could eventually enable genetic screening or targeted treatments.

The numbers in context

585 screened, 28 CHS + 12 controls genotyped. COMT mutation OR: 12.0 (p=0.012). ABCA1 OR: 8.4 (p=0.012). CYP2C9 OR: 7.8 (p=0.043). DRD2 OR: 6.2 (p=0.031). TRPV1 OR: 5.8 (p=0.015). 93% used flower or concentrates, multiple grams/day. 15.6% had cannabis dependency diagnosis. 56.6% had withdrawal symptoms.

How the study worked

Online screening questionnaire with 585 respondents. 205 qualified as CHS pool, 54 as cannabis-using controls. 28 CHS patients and 12 controls completed genomic testing via saliva kits. Both groups were high-frequency users of THC-predominant cannabis.

What this study cannot tell us

Very small genomic sample (28 patients, 12 controls) limits statistical power. Online recruitment introduces selection bias. Only 28 of 99 willing patients returned genetic kits. The study was not designed to establish clinical-grade genetic associations.

How to read the evidence

Preliminary: first-of-its-kind genomic analysis but limited by very small sample size (28 patients, 12 controls).

When this study was published

Published in 2022.

The bigger picture

If replicated, these genetic findings could transform CHS from a diagnosis of exclusion to one with biomarkers. The involvement of CYP2C9 (cannabinoid metabolism) and TRPV1 (pain/heat sensing) is particularly elegant, as it connects to known CHS features (metabolic sensitivity and hot bathing behavior).

Questions still open

Would a larger genomic study confirm these mutations? Could genetic screening identify cannabis users at risk for CHS before symptoms develop? Do these mutations affect response to CHS treatments?

Common questions

Why do some heavy cannabis users get CHS and others don't?

This study suggests genetics play a role. CHS patients had significantly more mutations in genes affecting how their bodies process cannabinoids (CYP2C9), sense pain and temperature (TRPV1), and regulate dopamine (DRD2), creating a biological vulnerability.

Could a genetic test predict CHS risk?

Not yet. The sample was too small for clinical application. But if these findings are confirmed in larger studies, genetic screening could eventually identify cannabis users at risk before they develop the severe vomiting episodes.

Read the original research

Cannabinoid Hyperemesis Syndrome Survey and Genomic Investigation.

Cannabis and cannabinoid research, 7(3), 336-344

View on PubMed ↗Publisher’s paper ↗

Citation

Russo, Ethan B; Spooner, Chris; May, Len; Leslie, Ryan; Whiteley, Venetia L. (2022). Cannabinoid Hyperemesis Syndrome Survey and Genomic Investigation.. Cannabis and cannabinoid research, 7(3), 336-344. https://doi.org/10.1089/can.2021.0046