On November 6, 2025, Nature Microbiology published the article “An updated evolutionary classification of CRISPR–Cas systems including rare variants,” co-authored by our PI Rolf Backofen.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated proteins (Cas) are naturally occurring systems that recognize and cleave specific DNA or RNA sequences, playing a vital role in the adaptive immunity of bacteria and archaea. Today, they are best known for their editing applications in genome engineering.
This new publication expands upon the 2020 classification of CRISPR–Cas systems — which comprised 2 classes, 6 types, and 33 subtypes — updating it to 7 types and 46 subtypes.
Highlights from this update include newly described functionalities of certain variants, refined insights into their phylogenetic origins through the discovery of additional variants, and analyses suggesting that while more subtypes and possibly even new types remain to be found, these are likely to be increasingly rare and will require substantial scientific effort to uncover.
👉 Learn more by reading the original article here.
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center –
University of Freiburg
