You can use results of the 23andMe genetic testing service to predict how you will respond to cannabis. Here’s how.

Much of the future of science and medicine lies in genetics.  The Human Genome Project sequenced the first human genome about 15 years ago to much fanfare. However, the impact of this landmark achievement has not yet truly been felt.

Little by little, progress has been made. Scientists are determining the link between specific polymorphisms (sites of genetic variation) and complex diseases. This knowledge can then be translated into diagnostics that predict risk for disease or which treatments will work best for a specific person.

Cannabinoids are no exception to this. Preliminary evidence has linked genetic variation in the endocannabinoid system to specific diseases. Other studies have shown that we may be able predict your risk for side effects of THC, such as cognitive deficits, psychosis, and dependence.

In the future, we may be able to determine who will benefit from cannabinoid therapy and also who should avoid it due to side effects. I believe that much of the trial and error in medical cannabis (and really, medicine in general) will eventually become a thing of the past.


Home Genetic Testing With 23andMe

What many people don’t realize is that you can already get a sneak preview of the future. Home genetic testing services such as 23andMe allow you to determine which common genetic variants you have. There are two huge caveats though:

  • These tests have not been approved by the FDA, at least not for anything I talk about below. You should know that all of this research is preliminary and it may be confirmed or refuted by future studies. You should not actually use any of this information to determine diagnosis or treatment.
  • This service does not give you a report for genes related to cannabis! So once you receive the test results, it is not very obvious how to find out which genes are important and which version of the genes you have.

This guide will help you determine your cannabinoid-related genetic variants using the 23andMe site. As I write more articles on different genes, I will continually update this guide. I do realize that there are other genetic testing services, but since 23andMe is the most common (and it is the one that I have used myself), it is the one I will focus on.

[Purchase 23andMe kit from Amazon]


Steps for Checking Your Genotype with 23andMe

  • Go to the 23andMe website and sign in
  • Hover over Tools in the top menu and then click on Browse Raw Data

23andMe screenshot Tools

  • You will now be in the Raw Data Tool. From here, you can access any variant that is genotyped by 23andMe by searching or browsing.
  • There is a box in the middle that says “Search for a specific gene or marker (SNP)”. You can use this to search for a specific SNP ID number (the SNP ID numer usually starts with “rs”). I list the SNP ID numbers below for several important genes.

23andMe screenshot Browse Raw Data

  • As an example, I have searched for the *3 variant of the CYP2C9 gene (SNP ID = rs1057910). The results show the possible variants (A or C). In my case, I have two copies of the A version.

23andMe screenshot SNP search result

Below, I will show how to check several important variants in different genes that may affect how you respond to cannabis. I will be adding more in the future!



CYP2C9 is a gene for a drug metabolizing enzyme. It is the most important enzyme for metabolism of THC. Genetic variants of CYP2C9 have been associated with:

Relevant variant: *1 vs. *3 (rs1057910)

  • A/A (*1/*1) = Fast metabolizer. Weaker effects of THC and more likely to fail a urine drug test.
  • A/C (*1/*3) = Intermediate metabolizer.
  • C/C (*3/*3) = Slow metabolizer. Stronger effects of THC and more likely to pass a urine drug test.



COMT is a gene for a dopamine-metabolizing enzyme present in your neuronal synapses. It is one of the most important genes for determining side effects of cannabis use. Genetic variants of COMT have been associated with:

Relevant variant: Val158Met (rs4680)

  • A/A (Met/Met) = Low COMT activity. Generally more protected from certain side effects of cannabis use.
  • A/G (Met/Val) = Intermediate COMT activity.
  • G/G (Val/Val) = High COMT activity. General more susceptible to certain side effects of cannabis use.



The ABCB1 gene encodes the P-glycoprotein (P-gp) drug transporter, which controls THC brain penetration. Genetic variants of ABCB1 have been associated with:

Relevant variant: C3435T (rs1045642)

  • G/G (C/C): High P-gp expression. Higher risk of cannabis dependence.
  • G/A (C/T): Intermediate P-gp expression.
  • A/A (T/T): Low P-gp expression. Lower risk of cannabis dependence.


More genes to come! As I cover details of other genes, I will add them here.

[Purchase 23andMe kit from Amazon]


[Featured image: 23andMe]

Last modified: October 16, 2017

3 Responses to " How To Determine Your Genetic Variants Important For Cannabis "

  1. Raychelle says:

    I am TT for the rs2494732 but DID have pot psychosis. I love hemp CBD oil and I believe pot is super for those who need it and I would even take it if I were in need. But not for fun. It was very scary, but I am still a supported of legalization.

  2. Johannes says:

    Love your article! Thanks for making my 23andme data more useful.
    Please post a comment when you update the article, so I will get an email notification 🙂

    I have the A/A variant of the CYP2C9 enzyme. Even though I passed a home drugtest after just two weeks of abstinence (after having vaporized daily for years). So please note that a predisposition to something doesn’t mean you automatically fall into that category.

    Some more genes I found out to be useful (using the amazing promethease reports):
    – rs2494732 (“odds of cannabis-associated psychosis”)
    – rs6454674, rs806368, rs324420 (“risk of the development of substance dependence”)
    – rs1049353 (“Cannabinoid receptor 1 (CNR1) gene: impact on antidepressant treatment response and emotion processing in major depression”)
    – rs806377 (“cannabis dependence symptoms in adolescents”)

    Looking forward to your updates!

    • Prof of Pot says:

      There’s a lot more! I have a folder with dozens of studies. For each one, I will write a separate post covering what they found in depth. This guide will just be focused on how to determine which version of the gene you have.

      You’re right, for all of these variants, it increases or decreases your risk, but they are not deterministic. For drug testing, there are variants in other enzymes besides CYP2C9 that I suspect also protect against failing a drug test. They haven’t been studied yet in the context of cannabis, so I haven’t written about them, but I will send you which ones they are later to see if you have them.

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