While no single SNP was genomewide significant for the count of DSM criteria, gene-level testing identified MEI1 (meiotic double-stranded break formation protein 1). Relative to other tissues, MEI1 is more robustly expressed in the testes and variants in the gene have been associated with azoospermia due to early and complete meiotic arrest (62). In parallel, there is compelling epidemiological and biological support for the relationship between prolonged/heavy cannabis use and male reproductive health, including fertility. Weekly cannabis use has been associated with a 28–29% reduction in sperm concentration and count (63). The endocannabinoid system actively participates in the regulation of male fertility (64), including by promoting meiosis via CB2 activation (65). Therefore, the possibility of shared genetic pathways to male fertility and heavy cannabis use might provide a plausible alternative to more causal explanations. However, we are not aware of any prior studies that link MEI1 to cannabis use or addiction.
