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Common Mechanisms of Disease-2 > Abnormalities in Chromosom Structure ( Self and Lecture ) > Flashcards

Abnormalities in Chromosom Structure ( Self and Lecture ) Flashcards

1
Q

What is the leading cause of intellectual disability and pregnancy loss?

A

Abnormal structure of chromosomes.

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2
Q

What does a metacentric chromosome look like ?

A

Two long arms and two short arms combined at the centromere.

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3
Q

What does a sub-metacentric chromosome look like?

A

Two very short arms, and two short arms combined at the centromere.

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4
Q

What does an acrocentric chromosome look like?

A

Two short arms combined at the centromere with two bairly discernable arms sticking off of the centromere.

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5
Q

If you wanted to diagnose deletions what resolution would you want the chromosome at?

A

Very condensed forms make it easy to discern chromosomal deletions.

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6
Q

What is the relation to chromosomal condensation to band resolution?

A

More condensed means there will be a lower band resolution.

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7
Q

What two things are required for chromosome stability?

A

One Centromere and two terminal telomeres.

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8
Q

What do you call a rearrangement where the net amount of genomic material stays the same?

A

A balanced rearrangement

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9
Q

What is an imbalanced rearrangement?

A

When the net genetic material does not stay the same

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10
Q

What is a partial trisomy?

A

Rearrangement that results in 3 copies of a chromosome segment.

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11
Q

What is a partial monosomy?

A

Rearrangement that results in one copy of a chromosome segment.

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12
Q

What does De Novo mean?

A

A structural abnormality that is new

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13
Q

What is a familial abnormality?

A

One that passes through a familial pedigree

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14
Q

What is a constitutional abnormality?

A

Menas it is present in all cells in the body

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15
Q

What is an acquired abnormality?

A

Arises in somabit cells of a single tissue. Usually applied to cancer lineages.

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16
Q

What will an autosomal imbalance cause?

A

Developmental delay, Growth Delay, Facial Dysmorphology and physical malformations.

17
Q

What results in a worse phenotype, alterations in autosomes or sex chromosomes.

A

Autosomal inbalance results in a more severe phenotypic change. This is due to the fact that the body can survive with only one X and the second X is usually down regulated.

18
Q

What is a reciprocal translocation?

A

Break and Exchange of gene segments between two non homologous chromosomes

19
Q

Which is the long arm of a chromosome, P portion or Q portion ?

A

P portion. “P is for Petite”

20
Q

What is the most likely segregation pattern for a reciprocal translocation?

A

Alternate, meaning the gamete recieves the two normal or two abnormal chromosomes.

21
Q

What is the risk associated pattern of reciprocal translocation?

A

Adjacent segregation, where the gamete receives one normal and one abnormal chromosome.

22
Q

Why does adjacent translocation carry a high risk ?

A

The gamete will have an unbalanced karyotype which will result in a partial monosomy and partial trisomy

23
Q

What type of chromosomes will undergo robertsonian translocation?

A

Acrocentric chromosomes

24
Q

Describe a Robertsonian Translocation.

A

Long arm fusion of two acrocentric chromosomes. The fusion chromosome has a single functional centromere.

25
Q

Which chromosomes are the acrocentric ones?

A

13, 14, 15, 21, 22

26
Q

What is the chrom number of a balanced carrier after a Robertsonian Translocation?

A

45

27
Q

What happens to the short arm material after a Robertsonian translocation?

A

It is disgarded.

28
Q

What is a terminal deletion?

A

Single break or loss of a terminal broken segment.

29
Q

What is a interstitial deletion?

A

Two breaks of one arm and a loss of segment and rejoining of broken arms

30
Q

What is an isochrone ?

A

An unbalanced chromosome that is a result of a misdivision at metaphase.

31
Q

What two clinical syndromes are a result of isochrome formation?

A

Turner Syndrome,

32
Q

What is a paracentric inversion?

A

2 Breaks in the same arm

33
Q

What is a pericentric inversion?

A

A break in the P arm and a break in the Q arm.

34
Q

What differentiates cancer cytogenetics from normal cytogenetics?

A
  • The abnormalities are acquired and restricted to malignant cells.
  • Genes are located at break points
  • There are hundreds of specific rearrangements.
35
Q

What type of acquired abnormalities are characteriestic of Cancer Cytogenetics?

A

Acquired and are both Numerical and Structural

36
Q

As the malignancy advances what happens to the abnormality of the karyotype?

A

As the malignancy advances the abnormality of the karotype will advance

Common Mechanisms of Disease-2 (24 decks)

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