CHROMOSOMAL ABERRATIONS Flashcards

1
Q

Breakage of a chromosome that leads to a variety of rearrangements affecting the genes of that chromosome

Even if all chromosomes are present in normal numbers, abnormalities in the chromosome structure may cause disorder

A

Chromosomal Aberrations

Or Alterations of Chromosomal Structure

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2
Q

Occurs when a fragment of a chromosome is lost

A

Deletion

Large deletions tend to have the most serious effects

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3
Q

Deletion that occurs towards the end of a chromosome

ABC O DEFG → BC O DEFG

A

Terminal Deletion

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4
Q

Deletion that occurs from the interior of chromosomes

ABC O DEFG → A O DEFG

A

Interstitial Deletion

or Intercalary Deletion

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5
Q

Small deletion up to 5MB, a doze of genes

MB: Million base pairs

A

Microdeletion

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6
Q

Occurs when a fragment from one chromosome joins a homologous chromosome

A

Duplication

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7
Q

Duplicated segment is present in another genome

ABC O DEFG → LMN O PQREFG

A

Interchromosomal Duplication

ABC O DEFG → LMN O PQREFG

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8
Q

Duplicated segment is present in the same chromosome

A

Intrachromosomal Duplication

3 Subtypes for Tandem Repeat

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9
Q

Tandem Repeats under Intrachrosomal Duplication

Gene order of duplicated segment is that of the original segment

Immediately after original segment

ABC O DEFG → ABC O DEFGEFG

A

Direct Tandem

Intrachromosomal Duplication

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10
Q

Tandem Repeats under Intrachrosomal Duplication

Gene order of the duplicated segment is reversed

ABC O DEFG → ABC O DEFGGFE

A

Reverse Tandem

Intrachromosomal Duplication

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11
Q

Tandem Repeats under Intrachrosomal Duplication

Duplicated segment is removed from the original segment

ABC O DEFG → ABC O DEFG ?? [TBF]

A

Displaced Tandem

Intrachromosomal Duplication

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12
Q

Occurs when a fragment breaks off reattaches within the same chromosome in an altered orientation

All the genes are still present in their normal number, but switching is present. Not as bad as getting syndromes from the other types

A

Inversion

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13
Q

Inversion that does not include the centromere

Either the p or q arm is inverted

A

Paracentric Inversion

ABC O DEFG → ABC O DEFG ?? [TBF]

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14
Q

Inversion that includes the centromere

Both the p or q arm is inverted

A

Pericentric Inversion

ABC O DEFG → ABC O DEFG ?? [TBF]

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15
Q

Occurs when a chromosomal fragment attaches to a non-homologous chromosome

A

Translocation

Like inversions, translocations may or may not be harmful

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16
Q

Chromosomal changes present in sperm or egg

A

Chromosomal Translocation

17
Q

Translocation where two non-homologous chromosomes exchange segments

A

Reciprocal Translocation

18
Q

Translocation caused by two particular chromosomes joining together

Only occurs with chromosomes: 13, 14, 15, 21, 22

Occurs when the long arms of two acrocentric chromosomes fuse at the centromere and the two short arms are lost

A

Robertsonian Translocation

A usual type of chromosome rearrangement

19
Q

Identify the Type of Aberration

Wolf-Hirschhorn Syndrome

also known as Pitt Syndrome

Caused by a ____ of a distal short arm of chromosome 4

A

Deletion

20
Q

Identify the Type of Aberration

Jacobsen Syndrome

also known as 11q terminal ____

A

Deletion

21
Q

Identify the Type of Aberration

Cat-eye Syndrome

Most often caused by a chromosome abnormality called an inverted ____ 22 ( ____ of the chromosome 22)

A

Duplication

22
Q

Identify the Type of Aberration

Edward’s Syndrome

Trisomy 18: Occurs when a baby is born with three copies of chromosome 18 instead of two

A

Duplication

23
Q

Identify the Type of Aberration

Patau Syndrome

Trisomy 13: Occurs when a baby is born an additional copy of all or part of chromosome 13

A

Duplication

24
Q

Identify the Type of Aberration

Hemophilia A

F8 gene (X chromosome) ____

A

Inversion

25
Q

Identify the Type of Aberration

____ Down Syndrome

Occurs as a ____ between chromosome 14 and 21

A

Translocation

26
Q

Down Syndrome

Trisomy 21: Occurs when a baby is born with three copies of chromosome 21

A

Duplication

27
Q

Types of Chromosomal Aberrations (4)

A
  1. Deletion
  2. Duplication
  3. Inversion
  4. Translocation