Cannabis, Intraocular Pressure, and the Growth Arrest-Specific 7 (GAS7) Gene: A Retrospective Analysis

Background Intraocular pressure (IOP) is a highly heritable risk factor for primary open-angle glaucoma (POAG), with at least 27 related genes; however, we are still not aware as to which receptors or genes that the main components of cannabis use to lower IOP. Methods In the current study, we used data from the UK Biobank (UKBB) to assess the relationship of growth arrest-specific 7 (GAS7) with IOP and cannabis in 37,046 subjects. GAS7, at chromosome 17p31.1, is quite close to a cannabis receptor at chromosome 17p31.3. For comparison, we chose a second IOP/glaucoma gene, CDKN2B-AS1 on chromosome 9p21.3, with no known relationship to cannabis. In addition, we examined the effect of CB1, GPR18, and cannabis on IOP; these two genes are associated with cannabis IOP reduction in mice. Results Total cannabis use versus IOP and genotypes of GAS7 SNP rs9913911 in the 37,046 subjects showed significant variation [p<0.001, univariate analysis of variance (ANOVA)]. Carriers of the GAS7 rs9913911 minor allele G had lower IOP with increased cannabis use. Total cannabis use versus IOP of genotypes of CDKN2B-AS1 SNP rs944801 in 37,046 subjects had IOP variability with cannabis use that was insignificant (p=0.138). We analyzed the relationship of CB1 SNP rs806365 and GPR18 SNP rs3742130 with cannabis use and IOP, which was insignificant. CB1 and GPR18 are probably not involved in cannabis-associated human IOP reduction, unlike what has been reported in mice. Conclusion Cannabis-based treatments, which apparently act on the GAS7 gene, can be utilized to reduce IOP. However, their disadvantages outweigh their advantages, which was not the case when the initial reports of marijuana's effects on IOP were published in the 1970s. Hence, cannabis-based glaucoma treatments are now of questionable value.