Which of the following statements is incorrect for the polymerase chain reaction (PCR)?

PCR is useful only when pathogen concentration is very high in the body.

The correct answer is Option (4) –PCR is useful only when pathogen concentration is very high in the body.

PCR is a powerful technique used to detect the presence of pathogens (such as bacteria and viruses) even before they produce visible disease symptoms. Normally, the suspicion of a pathogen arises when disease symptoms manifest, and the pathogen concentration is already significantly high in the body.

However, PCR enables the detection of very low pathogen concentrations during the early stages of infection when symptoms are not yet apparent. By amplifying the nucleic acids of the pathogen, PCR can provide early and accurate detection.

In medical practice, PCR is routinely employed to detect HIV in suspected AIDS patients and to identify mutations in genes of suspected cancer patients. Moreover, it is a valuable tool for identifying various other genetic disorders.

In summary, PCR's ability to amplify and detect small amounts of pathogenic nucleic acids allows for early diagnosis and monitoring of infectious diseases and genetic disorders, facilitating timely interventions and improved patient outcomes.