CSMLS Molecular Diagnostics 3

Question 1

What is the purpose of an internal control in a molecular diagnostic assay?

Accepted Answer

To detect PCR inhibition and confirm successful nucleic acid extraction

Answer

To calculate the exact copy number of the pathogen

Answer

To identify any contaminating organisms in the sample

Answer

To set the fluorescence threshold for Ct determination

Question 2

High-resolution melt (HRM) analysis detects sequence variants by monitoring:

Accepted Answer

Changes in the melting profile of PCR products as they are heated

Answer

Differences in fragment size after restriction digestion

Answer

Fluorescence emitted by a sequence-specific TaqMan probe

Answer

Hybridization intensity of labeled probes on a microarray

Question 3

Loop-mediated isothermal amplification (LAMP) is advantageous over PCR in resource-limited settings because:

Accepted Answer

It amplifies target DNA at a constant temperature without thermal cycling equipment

Answer

It provides higher sensitivity than real-time PCR

Answer

It can sequence amplicons directly without electrophoresis

Answer

It requires no primers and works on any nucleic acid

Question 4

Multiplex PCR panels used in clinical microbiology laboratories are designed to:

Accepted Answer

Simultaneously detect multiple pathogens in a single reaction

Answer

Determine minimum inhibitory concentrations for antibiotics

Answer

Genotype a single organism at all its resistance loci

Answer

Measure the host immune response to infection

Question 5

In clinical transplantation, high-resolution HLA typing is most accurately performed by:

Accepted Answer

Sequence-based typing (SBT) or PCR-SSO

Answer

Complement-dependent cytotoxicity (CDC) testing

Answer

Flow cytometric crossmatch

Answer

ELISA for anti-HLA antibodies

Question 6

Analytical sensitivity in a molecular diagnostic test refers to:

Accepted Answer

The lowest concentration of target nucleic acid reliably detected above background

Answer

The proportion of infected patients who test positive

Answer

The ability of the assay to distinguish the target from closely related organisms

Answer

The proportion of non-infected patients who test negative

Question 7

The negative predictive value (NPV) of a molecular diagnostic test describes:

Accepted Answer

The probability that a negative result correctly means the patient is disease-free

Answer

The probability that a positive result is a true positive

Answer

The proportion of all tested patients who are truly negative

Answer

The proportion of diseased patients who test positive