Journal of Biotechnology, Computational Biology and Bionanotechnology

In spite of an increase of a number of sequenced genomes, 20-30% of Open Reading Frames (ORFs) do not show detectable sequence similarity to other sequences in databases and functions of their products have not been recognized. These ORFs are called ORFans and their abundance has been referred to as a “mystery”. A large fraction of ORFans are probably spurious non-coding ORFs generated by protein coding sequences or repeat sequences. Some ORFans are probably quickly evolving genes specific to narrow phylogenetic lineages. The most interesting group of ORFans are de novo generated genes with new functions and structures which may find some applications in biotechnology and medicine. It is also possible that some ORFans code for RNA regulatory molecules.