Alison Sinclair's article on the polymerase chain reaction1 was an excellent, concise review of the topic, but it contained an important error.
Reverse transcriptase polymerase chain reaction is a valuable tool in research, diagnosis and patient management in certain diseases, particularly HIV infection. The article mentions Herpes simplex virus as an example of the RNA viruses that can be detected by this method. However, members of the virus family Herpesviridae, which contains Herpes simplex virus 1 and 2 as well as varicella zoster virus and Epstein–Barr virus, all have DNA as their genomic material.2
Stephen R. Walsh Infectious Diseases Massachusetts General Hospital Boston, Mass.