Chromosomal Abnormalities in Genetics
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Questions and Answers

Which mode of segregation will yield normal or balanced gametes in a balanced translocation carrier?

  • 3:1 segregation
  • 1:1 adjacent segregation
  • 2:2 alternate segregation (correct)
  • 4:0 segregation

What factor does NOT influence the segregation outcomes for balanced translocation carriers?

  • Relative size of chromosomes involved
  • Location of the breakpoints
  • Proximity to the centromere
  • Absolute length of chromosomes (correct)

In a karyotype, which inversion is particularly challenging to detect?

  • Isocromosome of chromosome 17
  • Recombinant chromosome involving chromosome 7
  • Pericentric inversion involving chromosome 3
  • Paracentric inversion on chromosome 16 (correct)

What does the term 'stemline' refer to in oncology nomenclature?

<p>The most basic clone of a tumor cell population (D)</p> Signup and view all the answers

Which of the following is NOT a structural abnormality mentioned?

<p>Chromatid exchanges (C)</p> Signup and view all the answers

What is a potential consequence of balanced chromosomal rearrangements?

<p>They may disrupt gene expression through breakpoints. (C)</p> Signup and view all the answers

Which type of inversion involves the centromere being included in the inverted segment?

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

What is the risk for a constitutional carrier of a translocation to have a liveborn child with a congenital anomaly?

<p>0-30% (B)</p> Signup and view all the answers

What does the notation 't(9;22)(q34;q11.2)' indicate?

<p>A reciprocal translocation involving chromosomes 9 and 22. (B)</p> Signup and view all the answers

Which of the following best describes the structural abnormality known as isochromosomes?

<p>Chromosomes with two identical arms resulting from a transverse division. (C)</p> Signup and view all the answers

Flashcards

Reciprocal translocations

A chromosomal abnormality where two non-homologous chromosomes exchange segments. The exchanged segments can be of equal or unequal size. Both chromosomes may be affected, resulting in a derivative chromosome.

Deletions

A chromosomal abnormality where a chromosome segment is missing. The deletion can be terminal (at the end of the chromosome) or interstitial (within the chromosome).

Duplications

A chromosomal abnormality where a chromosome segment is duplicated. The duplication can be terminal or interstitial.

Insertions

A chromosomal abnormality where a chromosome segment is transferred from one chromosome to another. The insertion can be terminal or interstitial.

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Ring chromosomes

A chromosomal abnormality where a chromosome breaks and the broken ends fuse to form a ring. These chromosomes often show instability and may be lost during cell division.

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Meiosis in Translocation Carriers

The process where chromosomes separate and are distributed into gametes (sperm and egg cells). In balanced translocation carriers, only 2:2 alternate segregation leads to normal or balanced gametes. All other segregation patterns result in unbalanced gametes, which can lead to genetic disorders.

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Isochromosomes

A type of structural abnormality where a chromosome has two identical arms resulting from a misdivision of the centromere. Can be a q arm isochromosome (two long arms) or a p arm isochromosome (two short arms).

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Stemline, Sideline and Idem

A system used in cancer genetics to describe the different cell populations in a tumor. The stemline is the most basic clone, listed first. Sidelines are additional subclones, listed after the stemline. 'Idem' indicates that the karyotype is the same as the one listed first, with additional changes.

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