Abstract from the full report on the study conducted:
Public comfort with Cannabis (marijuana and hemp) has recently increased, resulting in previously strict Cannabis regulations now allowing hemp cultivation, medical use, and in some states, recreational consumption. There is a growing interest in the potential medical benefits of the various chemical constituents produced by the Cannabis plant. Currently, the University of Mississippi, funded through the National Institutes of Health/National Institute on Drug Abuse (NIH/NIDA), is the sole Drug Enforcement Agency (DEA) licensed facility to cultivate Cannabis for research purposes. Hence, most federally funded research where participants consume Cannabis for medicinal purposes relies on NIDA-supplied product. Previous research found that cannabinoid levels in research grade marijuana supplied by NIDA did not align with commercially available Cannabis from Colorado, Washington and California. Given NIDA chemotypes were misaligned with commercial Cannabis, we sought to investigate where NIDA’s research grade marijuana falls on the genetic spectrum of Cannabis groups. NIDA research grade marijuana was found to genetically group with Hemp samples along with a small subset of commercial drug-type Cannabis. A majority of commercially available drug-type Cannabis was genetically very distinct from NIDA samples. These results suggest that subjects consuming NIDA research grade marijuana may experience different effects than average consumers.
Another article on this matter in NORML provides more details:
Marijuana grown by the University of Mississippi for clinical research purposes is genetically divergent from strains of cannabis commercially available in retail markets, according to an analysis prepared by researchers at the University of Northern Colorado. Since 1968, the University of Mississippi farm, which is governed by the US National Institute on Drug Abuse, has held the only available federal license to legally cultivate cannabis for FDA-approved research.
Authors reported that samples available via the U-Miss program shared genetics typically associated with industrial hemp, not commercially available cannabis. They concluded: “NIDA research grade marijuana was found to genetically group with hemp samples along with a small subset of commercial drug-type cannabis. A majority of commercially available drug-type cannabis was genetically very distinct from NIDA samples. These results suggest that subjects consuming NIDA research grade marijuana may experience different effects than average consumers.”