Molecular Diagnostic Techniques
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Questions and Answers

What is one major disadvantage of PCR compared to other methods?

  • More expensive than serological methods. (correct)
  • Involves manual sample handling.
  • Requires a longer processing time.
  • Less sensitive than serological methods.

Which step is NOT part of the FISH technique?

  • Visualizing the sample under fluorescence microscope.
  • Hybridizing the probe to the complementary DNA sequence.
  • Amplifying the target DNA using a thermal cycler. (correct)
  • Washing the samples to remove unbound probes.

Why is PCR considered more sensitive compared to serological methods?

  • It identifies proteins rather than nucleic acids.
  • It works with a broader range of sample materials.
  • It requires no quality control measures.
  • It can detect lower concentrations of pathogens. (correct)

What is one of the advantages of using FISH in molecular diagnostics?

<p>It can analyze multiple DNA sequences simultaneously. (B)</p> Signup and view all the answers

Which factor can lead to false positive results in PCR?

<p>Contamination of specimens. (D)</p> Signup and view all the answers

What is a key advantage of using microarrays in molecular diagnostics?

<p>They can simultaneously detect several pathogens. (C)</p> Signup and view all the answers

What limitation is associated with traditional tumor marker tests?

<p>Results must be interpreted with additional medical information. (C)</p> Signup and view all the answers

What is a significant disadvantage of using microarrays?

<p>They are too expensive for routine diagnostics. (C)</p> Signup and view all the answers

Which molecular diagnostic technique allows for thorough genomic profiling in cancer treatment?

<p>Next-generation sequencing (A)</p> Signup and view all the answers

Which of the following statements about tumor marker tests is true?

<p>Elevated markers may occur even in individuals without cancer. (C)</p> Signup and view all the answers

What is a known disadvantage of low-cost molecular diagnostic techniques?

<p>They may cause laboratory contamination of samples. (C)</p> Signup and view all the answers

How does chemotherapy potentially affect tumor marker levels?

<p>It may cause a slight and insignificant increase. (A)</p> Signup and view all the answers

What is a common requirement for molecular diagnostic techniques like microarrays?

<p>Necessity for nucleic acid amplification (A)</p> Signup and view all the answers

Flashcards

PCR (Polymerase Chain Reaction)

A molecular technique used to amplify specific DNA sequences, providing high sensitivity and specificity for detecting pathogens or genetic mutations.

Fluorescence In Situ Hybridization (FISH)

A molecular technique that uses fluorescent probes to label specific DNA sequences in chromosomes, enabling the detection of gene rearrangements, deletions, or amplifications.

What is an advantage of using PCR in diagnostics?

A main advantage of PCR is its sensitivity, meaning it can detect even tiny amounts of DNA, making it useful for diagnosing infections or identifying genetic changes.

What is one disadvantage of using PCR in diagnostics?

Contamination is a risk with PCR, meaning that foreign DNA can be introduced into the sample, leading to false-positive results.

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What is FISH used for?

FISH can be used to identify specific chromosomes or chromosomal regions in a sample.

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Biomarker tests

A diagnostic technique that uses a sample of tissue, blood, or other body fluid to check for specific molecules, like genes or proteins, that indicate a disease like cancer.

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Genetic tests

A laboratory method using a sample of tissue or fluid to look for specific genes or proteins to identify cancer or its type.

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Tumor sequencing

Techniques analyzing a person's tumor's whole genomic profile, including DNA sequences and mutations, to tailor treatment plans based on individual genetic makeup.

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Tumor marker tests

A laboratory technique using a sample of tissue or fluid to look for the presence of tumor markers, proteins that can be indicative of cancer.

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Next-generation sequencing (NGS) for tumor profiling

Molecular diagnostic techniques that analyze the entire genome of a tumor, focusing on various aspects like mutations, gene expression, and methylation patterns, to understand the tumor's characteristics and guide treatment.

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Microarrays

Molecular diagnostic techniques that utilize a chip-like platform to examine a sample for the presence of multiple pathogens simultaneously, offering a broad screening approach.

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Microscopy

A diagnostic technique that involves examining a sample under a microscope to identify the presence of specific organisms or abnormalities, offering a visual approach to diagnosis.

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Immunohistochemistry

A diagnostic technique focusing on the identification and analysis of specific genes or proteins within a sample, often using antibodies or other binding agents to detect the target molecules.

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Study Notes

Molecular Diagnostic Techniques

  • Polymerase Chain Reaction (PCR):
    • Useful for detecting a wide range of pathogens, adaptable through various modifications.
    • Suitable for diverse sample types.
    • Highly sensitive and specific compared to antibody/antigen detection methods.
    • Disadvantages: Contamination can lead to false positives; it's more expensive than serological methods; it requires quality control.

Fluorescence in situ Hybridization (FISH)

  • FISH: Identifies specific DNA sequences/genes on chromosomes.

    • A process used for detection of specific DNA sequences or regions on chromosomes.
    • Cells are treated with mild detergent and alkali to prepare them for the procedure.
    • Fluorescent probes are labelled and target known sequences during the procedure.
    • Specificity in FISH is achieved through probes designed for targeted chromosomes or chromosomal sections.

  • FISH procedure:

    • Cells are prepared in a metaphase stage.
    • Fixed on a slide.
    • Treated with mild detergent and alkali.
    • Fluorescent probes are added and amplified using PCR.
    • Hybridized probes are viewed under a microscope for the detection of chromosomal regions.

  • Probe application: Allows for the use of different coloured fluorescent dyes to distinguish between various DNA sequences on a single chromosome if multiple sequences are being targeted.

  • Post hybridization process: Samples are washed to eliminate unbound probes and are viewed under fluorescent microscopes for gene identification.

    • Amplification, deletion, or duplication of genes can be easily identified using this procedure.

Microarrays

  • Advantages:
    • Detects nucleic acids and antibodies.
    • High sensitivity.
    • Simultaneous detection of multiple pathogens.
  • Disadvantages:
    • Expensive for routine use.
    • Typically requires amplification of nucleic acids prior to analysis.

Molecular Diagnostic Techniques for Cancer

  • Sequencing:
    • Next-generation sequencing (NGS) is a method that is crucial in genomic profiling of cancer and is used in tailoring treatment plans based on the unique genetic composition of each patient's tumour.
    • Biopsies, genetic tests, and biomarker tests are part of this type of analysis.

Biomarker Tests

  • Description: Laboratory procedures that use tissue, blood, or other body fluids to identify certain genes, proteins, or other molecules related to diseases like cancer—as possible indicators.
  • Examples: HER2 in breast cancer or EGFR in lung cancer.

Tumour Marker Tests

  • Importance: These tests aid in assessing treatment effectiveness.

    • Decreasing or normal tumour marker levels suggest treatment efficacy, while increasing levels may indicate treatment resistance or cancer recurrence.
    • Chemotherapy frequently causes a temporary increase in tumour marker levels due to the rapid cancer cell death and release of these markers.

  • Limitations:

    • Not sufficient for screening or diagnosing cancer on their own.
    • Need to integrate other tests, such as a thorough medical history, physical examination, and other lab tests, for more accurate diagnosis and treatment decisions.
    • Some tumour markers may be elevated in individuals without cancer, and various cancer types may share the elevated expression of certain markers, which could lead to misdiagnosis.
    • Tumour marker levels may rise only after cancer worsens. This makes it challenging to detect cancer early or determine if cancer has returned after treatment

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Related Documents

Advantages and Disadvantages of Molecular Diagnostic Techniques PDF

Description

Explore key molecular diagnostic techniques such as PCR and FISH. This quiz covers their applications, advantages, and limitations in detecting pathogens and specific DNA sequences. Test your knowledge on these critical methodologies used in modern diagnostics.

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