Cannabis exposure altered DNA methylation at autism-linked genes in lab-grown sperm cells | Research

The takeaway

Using a lab model of human sperm development, researchers found cannabis exposure changed DNA methylation at genes linked to genomic imprinting and autism spectrum disorder.

Researchers studying epigenetic effects of cannabis, and prospective parents interested in how paternal substance use may affect offspring.

2 of 10 randomly selected autism genes showed altered methylation

What the researchers found

In an in vitro human spermatogenesis model, cannabis exposure significantly altered DNA methylation at maternally imprinted genes (SGCE, GRB10, PEG3) and autism candidate genes (HCN1, NR4A2) in spermatogonial stem cell-like and spermatid-like cells.

Why it matters

This study provides a mechanistic link between paternal cannabis use and potential heritable changes at genes associated with autism, supporting epidemiological observations of increased ASD risk in children of cannabis-using fathers.

The numbers in context

Methylation changes found at 3 imprinted genes (SGCE, GRB10, PEG3) and 2 of 10 randomly selected ASD candidate genes (HCN1, NR4A2).

How the study worked

Used an in vitro human spermatogenesis model to simulate chronic cannabis exposure. Assessed DNA methylation at imprinted genes and 10 randomly selected ASD candidate genes in spermatogonial stem cell (SSC)-like and spermatid-like cells.

What this study cannot tell us

This is an in vitro model, not actual human sperm from cannabis users. Only 10 ASD candidate genes were sampled. The functional consequences of these methylation changes on offspring are not established.

How to read the evidence

Preliminary: in vitro model only, no human cohort data on actual offspring outcomes.

When this study was published

Published in 2022.

The bigger picture

The idea that a father's substance use before conception could affect offspring neurodevelopment through epigenetic changes challenges traditional assumptions and has major public health implications.

Questions still open

Do these methylation changes translate to actual autism risk in children? Are the effects reversible if cannabis use stops before conception? How long must exposure last to produce these changes?

Common questions

What is DNA methylation and why does it matter?

DNA methylation is a chemical modification that can turn genes on or off without changing the DNA sequence itself. Changes in sperm methylation can potentially be passed to offspring and affect their development.

What are imprinted genes?

Imprinted genes are expressed from only one parent's copy. Disrupting their methylation can have outsized effects because there is no backup copy to compensate.

Does this prove cannabis causes autism?

No. This study shows cannabis can change methylation at ASD-linked genes in a lab model of sperm cells. Whether these changes actually increase autism risk in children requires follow-up studies in human families.

Read the original research

Cannabis alters DNA methylation at maternally imprinted and autism candidate genes in spermatogenic cells.

Systems biology in reproductive medicine, 68(5-6), 357-369

View on PubMed ↗Publisher’s paper ↗

Citation

Schrott, Rose; Greeson, Katherine W; King, Dillon; Symosko Crow, Krista M; Easley, Charles A; Murphy, Susan K. (2022). Cannabis alters DNA methylation at maternally imprinted and autism candidate genes in spermatogenic cells.. Systems biology in reproductive medicine, 68(5-6), 357-369. https://doi.org/10.1080/19396368.2022.2073292