Molecular diagnostics

Molecular diagnostics detects disease-associated DNA or RNA sequences in biological samples. It can identify pathogens, inherited variants, and molecular changes linked to disease.

Polymerase chain reaction: A laboratory method that repeatedly copies selected DNA sequences, producing enough material for detection or analysis. PCR amplifies target DNA so rare disease-associated sequences become detectable.
Infectious disease diagnosis: The identification of infections using clinical findings and laboratory tests. Pathogen DNA or RNA can reveal infection before culture results are available.
Nucleic acid: A molecule, such as DNA or RNA, made of nucleotide units that stores or conveys biological information. DNA and RNA are the direct targets of molecular diagnostic assays.
Serology: The study or measurement of antibodies and antigens in serum and other bodily fluids. Serology detects immune responses or proteins, whereas molecular tests detect nucleic-acid sequences.
Contamination control: Practices that prevent unwanted material from entering samples, reagents, or laboratory work areas. Trace carryover of amplified DNA can produce false-positive results.
Reverse transcription polymerase chain reaction: A method that converts RNA into complementary DNA before amplifying selected sequences by PCR. It enables detection of RNA viruses and gene-expression targets.
Viral load: The amount of a virus measured in a defined volume of blood or other specimen. Quantitative molecular tests track viral burden and treatment response.
DNA: The nucleic acid that stores hereditary information in most organisms and many viruses. Many tests detect DNA variants or pathogen genomes.
Microbial culture: The growth of microorganisms under controlled laboratory conditions for identification or study. Culture detects viable organisms and can enable susceptibility testing; molecular assays detect target sequences.
False positive rate: The proportion of people without a condition who receive a positive test result. A positive molecular signal may not establish disease when prevalence or specificity is low.

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