In the last decade, the development and application of molecular techniques has revolutionised the diagnosis and monitoring of human diseases. Nucleic acids techniques, such as microbial DNA genotyping, analysis of restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR), are making progress in medical diagnostic laboratories. Sequence analysis of amplified DNA allows better identification of pathogen, detection of mutant genes and more accurate prognosis of certain diseases.