This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases.
The systematic name of this enzyme class is S-adenosyl-L-methionine:carnosine N-methyltransferase.
The genes encoding carnosine N-methyltransferase activity have been identified by Jakub Drozak and coworkers in 2013[1] and 2015.
[2] In birds and reptiles, the enzyme is encoded by histamine N-methyltransferase-like gene (HNMT-like).
[1] Importantly, the HNMT-like gene is absent from available mammalian genomes and in mammalian species, the formation of anserine is catalyzed by methyltransferase that is unrelated to the reptilian and avian enzyme and encoded by C9orf41/UPF0586 gene.