Questions and Answers
How are triplet repeat expansion disorders diagnosed?
Why does each triplet repeat expansion disorder need its own unique test for diagnosis?
How is a G-band karyotype prepared?
What is FISH and how can it be used in diagnostic applications?
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What are the differences between Metaphase FISH, Interphase FISH, and Chromosome painting?
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What genomic approaches are used in the diagnosis of human disorders?
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What is the strategy behind microarrays such as CGH Microarray, SNP Microarray, and cDNA Microarray?
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How can PCR be used to obtain a diagnosis of a genetic disorder?
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How is next generation sequencing being used in genomic applications?
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What is the difference between whole genome sequencing (WGS), whole exome sequencing (WES), gene panels, and single targeted gene sequencing?
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What types of mutations may be observed in the human genome and how are they categorized?
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What are the relative pros and cons of the genomic and genetic techniques described?
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Study Notes
Genomics in Diagnosis
- Genomics significantly enhances the accuracy of medical diagnosis by utilizing DNA analysis techniques.
- Essential techniques covered include DNA isolation, PCR, DNA sequencing, gene chips, next-generation sequencing, chromosomal analysis, FISH, and genomic microarrays.
- The triplet repeat expansion disorders require unique diagnostic tests due to their distinct genetic mechanisms.
- G-band karyotyping involves staining chromosomes to identify structural abnormalities.
- FISH (Fluorescence In Situ Hybridization) can detect specific DNA sequences in chromosomes, aiding in diagnosing genetic disorders.
- Types of FISH methodologies include:
- Metaphase FISH: analyzes chromosomes in metaphase, providing clear separation.
- Interphase FISH: examines nuclei in interphase, useful for detecting subtle chromosomal abnormalities.
- Chromosome painting (SKY FISH): visualizes entire chromosomes using multiple fluorescent dyes.
- Microarray techniques vary in method and application:
- CGH Microarray: compares the patient's DNA to a reference genome to identify copy number variations.
- SNP Microarray: focuses on specific single nucleotide polymorphisms to identify genetic variations.
- cDNA Microarray: assesses gene expression levels by comparing mRNA transcripts.
Diagnostic Techniques and Applications
- PCR (Polymerase Chain Reaction) amplifies specific DNA sequences, enabling the diagnosis of genetic disorders.
- Next-generation sequencing (NGS) allows simultaneous sequencing of multiple DNA strands, revolutionizing genomics.
- Differences in sequencing techniques include:
- Whole Genome Sequencing (WGS): analyzes the entire DNA sequence, offering comprehensive insights.
- Whole Exome Sequencing (WES): focuses on exons, the coding regions of genes, which constitute approximately 1% of the genome but contain most mutations associated with diseases.
- Gene panels: test for a specific set of genes known to be associated with certain disorders.
- Single targeted gene sequencing: isolates and sequences a single gene of interest.
- Mutations in the human genome can be categorized by type, including point mutations, insertions, deletions, and structural variations.
- It's crucial to understand the pros and cons of genomic versus genetic techniques, including resolution limits and diagnostic capabilities.
- A strong grasp of genetic testing and techniques is vital for effective patient care and successful interpretation of diagnostic results.
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Description
Explore the use of genomics in diagnostic practices with this quiz based on Dr. Mary Maj's lecture. This session is a part of the Basic Principles of Medicine 1 course, focusing on foundational concepts in medical genomics. Test your understanding of how genomics can impact diagnoses in medical practice.
