Podcast
Questions and Answers
What are the potential outcomes of deletions and duplications in paired mosaicism if the rearrangement occurs during the initial division?
What are the potential outcomes of deletions and duplications in paired mosaicism if the rearrangement occurs during the initial division?
- All cells will exhibit either deletions or duplications that are complementary. (correct)
- All cell lines will be normal.
- Mosaicism will be less dynamic.
- Only some cell lines will exhibit deletions.
In individuals with deletions and duplications, what happens during subsequent meiosis?
In individuals with deletions and duplications, what happens during subsequent meiosis?
- Rearrangements prevent any meiotic activity.
- Loops form to maximize alignment. (correct)
- Normal cell lines completely dominate the outcome.
- Only deletions are retained.
Which syndrome is specifically associated with a microdeletion of approximately 1.5 Mb in chromosome 7?
Which syndrome is specifically associated with a microdeletion of approximately 1.5 Mb in chromosome 7?
- Down Syndrome
- Williams Syndrome (correct)
- Prader-Willi Syndrome
- Angelman Syndrome
What is a common effect of duplications relative to their corresponding deletions?
What is a common effect of duplications relative to their corresponding deletions?
What is a possible consequence of dynamic mosaicism arising from deletions and duplications?
What is a possible consequence of dynamic mosaicism arising from deletions and duplications?
What is the term for acquiring a telomere from another chromosome?
What is the term for acquiring a telomere from another chromosome?
What is a potential result of gonadal mosaicism in a parent?
What is a potential result of gonadal mosaicism in a parent?
Which type of deletion involves a loss at both the terminal ends of a chromosome?
Which type of deletion involves a loss at both the terminal ends of a chromosome?
What kind of duplication has the same orientation as the original genomic segment?
What kind of duplication has the same orientation as the original genomic segment?
In paired deletions and duplications, which statement is true about their phenotypes?
In paired deletions and duplications, which statement is true about their phenotypes?
What can be a consequence of balanced familial structural rearrangements?
What can be a consequence of balanced familial structural rearrangements?
Which best describes pseudodominance?
Which best describes pseudodominance?
What is a characteristic of deletions in chromosomal rearrangements?
What is a characteristic of deletions in chromosomal rearrangements?
How are deletions and duplications related in genomic alterations?
How are deletions and duplications related in genomic alterations?
What is the significance of deletion size in relation to phenotypes?
What is the significance of deletion size in relation to phenotypes?
Which of the following syndromes is associated with specific deletion syndromes?
Which of the following syndromes is associated with specific deletion syndromes?
What impact do meiotic consequences of deletions and duplications have?
What impact do meiotic consequences of deletions and duplications have?
Which type of deletion occurs within the chromosome, resulting in a segment being lost?
Which type of deletion occurs within the chromosome, resulting in a segment being lost?
Study Notes
Deletions & Duplications
- Deletions & duplications are the most common class of clinical chromosomal rearrangements
- Postzygotic mitoses can produce paired deletions and duplications
- Paired deletions and duplications can be complementary if rearrangement occurs in the initial division
- If the rearrangement occurs later in the divisions, there is potential for normal cell lines to be present
- Cell lines of lesser viability may be lost
- Duplications have the potential to have the opposite phenotype of their deletion counterparts
- Duplications are an extra copy of a genomic segment, resulting in partial trisomy
- Duplications can be pure or combined with other rearrangements
- Tandem duplications are contiguous doublings of a segment
- Tandem duplications can be direct or inverted
- Direct tandem duplications are the most common form of detectable tandem duplications in humans
- Phenotypes of duplications are less severe than deletions
- Meiosis in individuals with deletions and duplications results in loop formation to maximize alignment
- Williams syndrome is caused by a ~1.5 Mb deletion on the long arm of chromosome 7
- Williams syndrome impacts ~30 known and predicted genes, including ELN and LIMK1
- Williams syndrome is associated with strengths in spoken language, music, and rote memorization, but difficulties with visual-spatial acuity
- Microdeletions are associated with Williams syndrome, Prader-Willi and Angelman Syndromes
Classic Deletions
- Terminal deletions have no discernable material beyond the site of breakage
- Terminal deletions may retain a telomere through acquisition from other chromosomes or telomerase
- Interstitial deletions have a proximal breakpoint and a more distal breakpoint after the missing material
- Interstitial deletions have a continuation of the normal chromosome banding pattern
Familial Rearrangements
- Balanced familial structural rearrangements can go generations without detection
- Balanced familial rearrangements are typically associated with high incidence of infertility and multiple spontaneous pregnancy losses
- Familial rearrangements are often unique/family-specific
- Risk for abnormal phenotype is higher for an individual with de novo rearrangements than for an individual who has inherited a similar rearrangement from a parent
Consequences of Rearrangements
- Rearrangements can result in loss or gain of gene activity, transcription, function, or protein-level activity
- Pseudodominance is the appearance of a recessive trait due to loss of the dominant allele
- Haploinsufficiency is the loss of one copy of a gene, with the remaining copy not enough to maintain full function
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Description
Test your knowledge on the mechanisms of genomic deletions and duplications. This quiz covers key concepts such as chromosomal rearrangements, paired deletions, and tandem duplications. Understand how these alterations affect phenotypes and cellular viability.
