A 2006 review of circular codes in genes

We present a review of circular codes in genes 10 years after they were discovered. After an introduction of the research context, codes are replaced in their historical aspect with the comma-free codes which have been searched but not found in genes over the alphabet {A, C, G, T}. Then, the circular codes identified in genes and genomes are presented according to 3 axes without mathematical notation: identification, evolution and possible function.