Chromosomal Deletions and Abnormalities
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Questions and Answers

What is the result of a large deletion of genetic material?

  • Inversion of that segment of chromosome
  • Monosomy for that segment of chromosome (correct)
  • Duplication of that segment of chromosome
  • Trisomy for that segment of chromosome
  • What type of deletion involves a single break of the terminal part of a chromosome?

  • Paracentric inversion
  • Interstitial deletion
  • Terminal deletion (correct)
  • Pericentric inversion
  • What is the characteristic cry of a newborn with Cri-du Chat syndrome?

  • High-pitched cry
  • Cat-like cry (correct)
  • Hoarse cry
  • Silent cry
  • What is the incidence of Cri-du Chat syndrome?

    <p>1 per 20,000 birth to 1 per 50,000 birth</p> Signup and view all the answers

    What type of deletion cannot be detected by Karyotype?

    <p>Microdeletion</p> Signup and view all the answers

    What is the result of an interstitial deletion of paternal chromosome 15?

    <p>Prader-Willi syndrome</p> Signup and view all the answers

    What type of inversion involves both p and q arms with centromere?

    <p>Pericentric inversion</p> Signup and view all the answers

    What is the effect of duplication of a chromosome part?

    <p>Gain of extra genetic material</p> Signup and view all the answers

    Which of the following types of chromosomal abnormalities can result in the deletion of a short arm of chromosome 5?

    <p>Terminal deletion</p> Signup and view all the answers

    What is the typical consequence of a large deletion of genetic material?

    <p>Incompatibility with survival to term</p> Signup and view all the answers

    Which of the following syndromes is caused by an interstitial deletion of paternal chromosome 15?

    <p>Prader-Willi syndrome</p> Signup and view all the answers

    What is the term for the process of reversing a segment of a chromosome?

    <p>Inversion</p> Signup and view all the answers

    Which of the following characteristics is NOT associated with Cri-du Chat syndrome?

    <p>Tall stature</p> Signup and view all the answers

    What is the purpose of FISH technique in detecting chromosomal abnormalities?

    <p>To detect micro-deletions</p> Signup and view all the answers

    Which of the following types of inversion involves only one arm of a chromosome?

    <p>Paracentric inversion</p> Signup and view all the answers

    What is the result of a terminal deletion of chromosome 5?

    <p>Cri-du Chat syndrome</p> Signup and view all the answers

    Study Notes

    Deletion and Structural Abnormalities

    • Deletion results in monosomy, usually incompatible with survival to term
    • There are two types of deletions: terminal deletion and interstitial deletion

    Terminal Deletion

    • Involves a single break of the terminal part of a chromosome, resulting in loss of the broken part
    • Example: Cri-du Chat syndrome (46,XX,5p- or 46,XY,5p-)
    • Characteristics of Cri-du Chat syndrome:
      • Deletion of the short arm of chromosome 5
      • Incidence: 1 per 20,000 to 1 per 50,000 births
      • Underdevelopment of larynx, resulting in a characteristic cat-like cry (Mewing cry)
      • Mental retardation
      • Microcephaly and facial anomalies

    Interstitial Deletion

    • Involves two breaks, resulting in loss of the intervening portion of the chromosome
    • Some interstitial deletions can occur as micro-deletions, which cannot be detected by karyotype and require FISH technique for detection
    • Examples: Prader-Willi syndrome (interstitial deletion of paternal chromosome 15, 15q11–q13) and Angelman syndrome (interstitial deletion of maternal chromosome 15, 15q11–q13)

    Other Structural Abnormalities

    • Duplication: extra copies of a chromosome part
    • Inversion: involves two breaks along the chromosome, resulting in reversal of a given segment
      • Pericentric inversion: inverted segment involves both p and q arms with centromere
      • Paracentric inversion: inverted segment involves only one arm (p or q)

    Deletion and Structural Abnormalities

    • Deletion results in monosomy, usually incompatible with survival to term
    • There are two types of deletions: terminal deletion and interstitial deletion

    Terminal Deletion

    • Involves a single break of the terminal part of a chromosome, resulting in loss of the broken part
    • Example: Cri-du Chat syndrome (46,XX,5p- or 46,XY,5p-)
    • Characteristics of Cri-du Chat syndrome:
      • Deletion of the short arm of chromosome 5
      • Incidence: 1 per 20,000 to 1 per 50,000 births
      • Underdevelopment of larynx, resulting in a characteristic cat-like cry (Mewing cry)
      • Mental retardation
      • Microcephaly and facial anomalies

    Interstitial Deletion

    • Involves two breaks, resulting in loss of the intervening portion of the chromosome
    • Some interstitial deletions can occur as micro-deletions, which cannot be detected by karyotype and require FISH technique for detection
    • Examples: Prader-Willi syndrome (interstitial deletion of paternal chromosome 15, 15q11–q13) and Angelman syndrome (interstitial deletion of maternal chromosome 15, 15q11–q13)

    Other Structural Abnormalities

    • Duplication: extra copies of a chromosome part
    • Inversion: involves two breaks along the chromosome, resulting in reversal of a given segment
      • Pericentric inversion: inverted segment involves both p and q arms with centromere
      • Paracentric inversion: inverted segment involves only one arm (p or q)

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    Description

    Learn about different types of chromosomal deletions, including terminal and interstitial deletions, and their effects on chromosome structure and development.

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