Agarose Gel Electrophoresis

question 1 of 18 course: Biomedical Science(Degree)
question 1 of 18 course: Biomedical Science(Degree)

Q: Which laboratory technique is used to separate DNA fragments by size?

Did You Know?

This scenario illustrates a common challenge with highly sensitive molecular diagnostics: detecting nucleic acid from organisms that may be present without causing disease. Dientamoeba fragilis is a commensal amoeboflagellate whose pathogenicity is debated. Traditional microscopy has low sensitivity for D. fragilis because trophozoites are fragile. The new multiplex PCR is detecting D. fragilis DNA at much higher rates, including in asymptomatic individuals. This likely represents the true prevalence of colonization, most of which is asymptomatic. The dramatic increase doesn't mean there's an outbreak; it reflects improved detection of a common commensal. The laboratory should add a comment to positive reports stating that D. fragilis is of uncertain pathogenicity and that its presence should be correlated with clinical symptoms. They should also consider reviewing the clinical significance with infectious disease specialists and possibly establishing criteria for reporting (e.g., only reporting when above a certain threshold or when other pathogens are absent). This prevents over-treatment of incidental findings.

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