16 Questions
What is the result of a large deletion of genetic material?
Monosomy for that segment of chromosome
What type of deletion involves a single break of the terminal part of a chromosome?
Terminal deletion
What is the characteristic cry of a newborn with Cri-du Chat syndrome?
Cat-like cry
What is the incidence of Cri-du Chat syndrome?
1 per 20,000 birth to 1 per 50,000 birth
What type of deletion cannot be detected by Karyotype?
Microdeletion
What is the result of an interstitial deletion of paternal chromosome 15?
Prader-Willi syndrome
What type of inversion involves both p and q arms with centromere?
Pericentric inversion
What is the effect of duplication of a chromosome part?
Gain of extra genetic material
Which of the following types of chromosomal abnormalities can result in the deletion of a short arm of chromosome 5?
Terminal deletion
What is the typical consequence of a large deletion of genetic material?
Incompatibility with survival to term
Which of the following syndromes is caused by an interstitial deletion of paternal chromosome 15?
Prader-Willi syndrome
What is the term for the process of reversing a segment of a chromosome?
Inversion
Which of the following characteristics is NOT associated with Cri-du Chat syndrome?
Tall stature
What is the purpose of FISH technique in detecting chromosomal abnormalities?
To detect micro-deletions
Which of the following types of inversion involves only one arm of a chromosome?
Paracentric inversion
What is the result of a terminal deletion of chromosome 5?
Cri-du Chat syndrome
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)
Learn about different types of chromosomal deletions, including terminal and interstitial deletions, and their effects on chromosome structure and development.
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