48 Questions
What is the leading known cause of intellectual disability and pregnancy loss?
Chromosome abnormalities
In what percentage of first-trimester spontaneous abortions are chromosome abnormalities seen?
50%
What has contributed many new insights in the field of cytogenetics?
Advances in molecular genetics
What has enabled researchers to specify whether an altered chromosome is derived from the mother or from the father?
Identification of DNA polymorphisms
Which condition is much rarer than triploidy at conception and among live births?
Tetraploidy
What is the term for cells that contain missing or additional individual chromosomes?
Aneuploid
What is the most common cause of aneuploidy?
Meiotic nondisjunction
What is the term for the presence of only one copy of a chromosome in an otherwise diploid cell?
Monosomy
Which type of trisomies are seen with appreciable frequencies among live births?
Autosomal trisomies
What is the term for the failure of chromosomes to disjoin normally during meiosis?
Nondisjunction
Which condition consists primarily of monosomies and trisomies?
Aneuploidy
What does the body tolerate more readily, excess genetic material or a deficit of genetic material?
Excess genetic material
Which staining technique developed in the 1970s produces chromosome bands facilitating the identification of individual chromosomes?
G-banding
What does the term 'karyotype' refer to?
The number and type of chromosomes present in an individual
What is the typical chromosome constitution for a normal male according to the text?
46,XY
Which staining technique is useful in identifying unknown chromosomal material?
NOR staining
What do major bands on each chromosome indicate?
The position of the centromere
What is a karyogram?
The printed display of chromosomes
Which technique is used for identifying chromosomal material in specific regions?
C-banding
What is the typical chromosome constitution for a normal female according to the text?
46,XX
What does the term 'karyotype' not include?
Chromosome length
Which technique is used to visualize the nucleolar organizer regions (NORs) on chromosomes?
NOR staining
What does the term 'karyogram' not represent?
The classification of chromosomes based on centromere position
Which staining technique is used to identify chromosomal material in specific regions, such as centromeres and telomeres?
C-banding
Which technique allows visualization of specific DNA sequences on chromosomes using fluorescent probes?
Fluorescence in situ hybridization (FISH)
What is the advantage of FISH over high-resolution banding approaches?
FISH provides better resolution
Which technique uniquely colors each chromosome for easy identification?
Spectral karyotyping
What is the main application of spectral karyotyping in clinical practice?
Detecting chromosome rearrangements in tumor cells
Which technique involves staining chromosomes during prophase or early metaphase?
High-resolution banding
What is the purpose of various banding techniques such as quinacrine, Giemsa, reverse, C, and NOR banding?
To identify individual chromosomes and structural abnormalities
What is the minimum size of deletions that FISH can detect?
1 million base pairs
Which technique is now rarely needed in clinical practice due to the increasing use of comparative genomic hybridization?
Spectral karyotyping
What is the main advantage of FISH in clinical applications?
It allows for faster analyses and diagnoses
Which technique can be used to test several common numerical abnormalities simultaneously in the same cell?
Fluorescence in situ hybridization (FISH)
What does the banding pattern of a G-banded karyotype help identify?
Individual chromosomes and structural abnormalities
Which technique increases the number of observable bands from about 300 to as many as 800?
High-resolution banding
Which technique offers the highest resolution for detecting deletions and duplications of less than 20 kb in size?
Cytogenomic microarray (CMA)
Which technique can detect loss of heterozygosity and uniparental disomy?
Cytogenomic microarray (CMA)
Which technique is commonly used in cytogenetics laboratories due to automation and minimal DNA requirements?
Cytogenomic microarray (CMA)
Which type of chromosomal abnormality can FISH detect?
Missing or additional chromosomal material
What does CGH detect?
Deletions and duplications of less than 20 kb
Which type of polyploidy is seen commonly in plants and less frequently in humans?
Tetraploidy
What is the cause of triploidy in about 1 in 10,000 live births?
Fertilization of an egg by two sperm (dispermy)
Which technique cannot detect balanced rearrangements of chromosomes?
Cytogenomic microarray (CMA)
What is the type of polyploidy seen in about 1 in 10,000 live births?
Triploidy
What does array CGH (aCGH) offer higher resolution than?
CGH
What does CGH utilize to detect losses or duplications of whole chromosomes or specific chromosome regions?
Labeled DNA from a test source and normal control cells
What does FISH detect in chromosomes?
Missing or additional chromosomal material
Study Notes
Cytogenetic Techniques and Chromosome Abnormalities
- FISH is a technique using labeled probes to detect chromosomal abnormalities in metaphase, prophase, or interphase chromosomes.
- FISH can detect missing or additional chromosomal material as well as chromosome rearrangements.
- CGH is a widely used technique to detect losses or duplications of whole chromosomes or specific chromosome regions.
- CGH utilizes labeled DNA from a test source and normal control cells, where excess quantities of labeled DNA indicate duplications and deletions.
- Array CGH (aCGH) offers higher resolution than traditional CGH, detecting duplications and deletions at a resolution of 50 to 100 kb or even less.
- Cytogenomic microarray (CMA) is a newer technique with even higher resolution, detecting deletions and duplications of less than 20 kb in size.
- CMA can also detect loss of heterozygosity and uniparental disomy, offering a wider range of diagnostic yield.
- Array CGH and CMA have become the most commonly used techniques in cytogenetics laboratories due to automation and minimal DNA requirements.
- These techniques cannot detect balanced rearrangements of chromosomes, such as reciprocal translocations or inversions.
- Polyploidy, the presence of a complete set of extra chromosomes in a cell, is seen commonly in plants and less frequently in humans.
- Triploidy is a type of polyploidy seen in about 1 in 10,000 live births, often resulting in spontaneous abortion and causing multiple anomalies.
- Triploidy can be caused by fertilization of an egg by two sperm (dispermy) or fusion of an ovum and a polar body, followed by fertilization by a sperm cell.
Test your knowledge of cytogenetic techniques and chromosome abnormalities with this quiz. Explore topics such as FISH, CGH, aCGH, CMA, and their abilities to detect chromosomal abnormalities. Learn about polyploidy, triploidy, and their causes and effects.
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