Unidentified reading frame. The open reading frames (ORFs) uncovered in the DNA of a species of interest are matched against those in large databases that contain all known ORFs from all kinds of organisms. A substantial number of the new ORFs are left over that do not resemble genes that encode any known proteins. These ORFs are therefore also URFs. Such genes are sometimes called orphans. (q.v.).
Subjects: Genetics and Genomics.