Ribonucleic acid (RNA) is a substance found in all living cells which acts as a controller of protein synthesis. It is similar in construction to its counterpart deoxyribonucleic acid (DNA), with the replacement of ribose for deoxyribose and the pyrimidine uracil for thymine. RNA also commonly acts as the genome for the majority of viruses, rather than DNA.
Following his exposure to a quantum fissure in 2370, Worf's cellular RNA was thrown into a state of flux which extended to the subatomic level. This was the first clue to the nature of Worf's quantum disassociation; essentially he was in the wrong quantum reality. (TNG: "Parallels")