CBGA is the first cannabinoid to be produced by the cannabis plant and is the root cannabinoid that leads to all others. Enzymes in the plant will convert CBGA to other cannabinoid acids like THCA, CBDA and CBCA. The enzymes in the plant  dictate which cannabinoid acid CBGA will be converted to.

To give a brief overview of what occurs in the cannabis plant when producing cannabinoids, the plant combines geranyl diphosphate and olivetolic acid to produce CBGA. Then enzymes in the plant then transform the CBGA into other cannabinoids. The THC synthase enzyme converts it to THCA, the CBD synthase converts the CBGA to CBD and the CBC synthase enzyme converts it to CBCA.
A lot of industrial hemp has recessive genes that prevent the production of the enzymes that convert CBGA to other cannabinoid acids, as a result of this many of these hemp strains may prove a good source for CBGA and its decarboxylated counter part, CBG.

Because CBGA is quickly converted into other cannabinoids, it is rare to find significant quantities in cannabis plant material, even fresh raw cannabis. Partly due to its rarity in cannabis medicines and partly due to general restrictions on cannabis research, very little has been discovered about the therapeutic properties of CBGA.
In Israel, Ruth Ross, and her team at the University of Aberdeen, presented research on CBGA's effect on receptor GPR55.
"Modulation of GPR55 Signally by Phytocannabinoids Measured Using the Alphascreen Assay. Using their assay, they found CBDA and CBGA modulated 2-4 times stronger than CBD and CBG. This provides the first evidence for a structure-activity relationship of cannabis constituents at GPR55."
This is relevant because GPR55 is involved in inflammation and cancer progression. The ability to block this receptor gives CBGA the potential for strong anti inflammatory and anti cancer effects.

It is important to understand that the research on CBGA and its modulation of GPR55, and even the research on this receptor itself, is still in its infancy and evidence for its therapeutic potential is minimal. So while CBGA may have potential as an anti inflammatory, anti bacterial and even an anti proliferative (anti cancer) compound, none of these qualities have been established to the degree that other cannabinoids have demonstrated such properties.