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Y1 - MCD > Genetics 1 > Flashcards

Genetics 1 Flashcards

1
Q

What is a malformation?

A

A morphological defect of an organ or part of the body caused by an intrinsically abnormal development process.

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2
Q

What is a disruption?

A

An extrinsic breakdown or interference with an originally normal developmental process.

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3
Q

What is a deformation?

A

Caused by mechanical factors and can normally be fixed with surgery.

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4
Q

What is dysplasia?

A

Abnormal organisation of cells into tissues. Caused by a single gene defect and is prone to a high recurrence risk.

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5
Q

What is a sequence?

A

A pattern of multiple abnormalities derived from a single known anomaly or mechanical factor.

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6
Q

What is a syndrome?

A

Multiple abnormalities that are thought to be pathologically related and not representing a sequence.

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7
Q

What is an association?

A

Non-random occurrence in two or more individuals. Cause is typically unknown.

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8
Q

What are the three types of chromosomal abnormalities? Give examples.

A

Structural - deletions, translocations or insertions
Numerical - aneuploidy
Mosaicism - caused by mitotic non-disjunction

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9
Q

What is robertsonian translocation?

A

Chromosome breaks at centromeres and the two long arms fuse together to form one long chromosome with a single centromere.

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10
Q

What is aneuploidy?

A

Loss or gain of one or more chromosomes.

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11
Q

What is monosomy?

A

The loss of one chromosome. Almost always lethal.

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12
Q

Example of monosomy?

A

Turners syndrome (X)

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13
Q

Symptoms of Turners syndrome?

A
  • Webbed neck
  • Aortic defects
  • Urinary defects
  • Short stature
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14
Q

How is Turners syndrome treated?

A

Growth hormone and oestrogen replacement.

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15
Q

What is trisomy?

A

Gain of one chromosome. Can be tolerated on certain chromosomes.

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16
Q

Give three examples of trisomy.

A
  • Trisomy 13: Patay syndrome
  • Trisomy 18: Edwards syndrome
  • Trisomy 21: Down syndrome
17
Q

Symptoms of Patay syndrome?

A
  • Heart defects
  • Mental retardation
  • Cleft palate
18
Q

Symptoms of Edwards syndrome?

A
  • Heart defects
  • Kidney malformation
  • Digestive tract defects
  • Mental retardation
19
Q

Symptoms of Down syndrome?

A
  • Craniofacial defects (small ears and epicanthic folds)
  • Short stature
  • Cardiac defects
  • Mental retardation
  • Limb defects (sandal toe gap)
20
Q

What is tetrasomy?

A

Gain of two chromosomes. Can be tolerated on some chromosomes.

21
Q

What is an example of tetrasomy?

A

Klinefelter’s syndrome (XXY)

22
Q

Symptoms of Klinefelter’s syndrome?

A
  • Taller than average
  • Infertility
  • Phenotypically male
  • Learning disabilities (IQ of 80-90)
23
Q

What are the rare variants of Klinefelter’s syndrome?

A

XXXY and XXXXY

24
Q

What is dosage compensation?

A

Mechanism that ensures equivalent gene expression between males and females.

25
Q

What three mechanisms are used in dosage compensation?

A

1) Inactivation of the X chromosome in females
2) Increased gene expression of the X chromosome in males
3) Decreased expression of both X chromosomes in hermaphrodites

26
Q

What is Di George syndrome and its symptoms?

A
  • Caused by a micro deletion
  • Cardiac defects
  • Thymic hypoplasia
  • Cleft palate
  • Hypokalaemia
27
Q

What is Marie-Charcot-Tooth disease and its symptoms?

A
  • Caused by a micro duplication
  • Muscular weakness and foot drop
  • Demyelination of peripheral nerves in adolescence, leading to absent reflexes, slow conduction and lack of sensation in lower limbs
28
Q

How is MCTDT1A treated?

A

Physiotherapy and corrective surgery

29
Q

What are chromosomes stained with to see the banding?

A

Giemsa

30
Q

Which arm of the chromosome is smaller.

A

P arm

31
Q

What is the advantages of next generation sequencing?

A
  • Increased sequencing volume (can sequence millions of DNA fragments simultaneously)
  • Greater sensitivity to rare variants
32
Q

How does Sanger/NGS sequencing work?

A

Fluorescent DNA polymerase adds nucleotides onto a growing template DNA strand.

33
Q

What is copy number variation?

A

When the number of copies of a particular gene varies between individuals.

34
Q

What are the implications of copy number variations?

A

Some cancers (breast cancer) are associated with increased copy numbers of particular genes whilst other disorders are associated with deletions (Prader-Willi and Angelman syndrome).

35
Q

Give example of a mutation in the same gene causing different disorder.

A

Cystic fibrosis and CAVD (congenital absence of the Vas Deferens)

36
Q

Give an example of the same disease caused by a different gene.

A

Haemophillia (F8 and F9 gene on X chromosome)

37
Q

Give an example of a disorder with two different patterns of inheritance.

A

Epidermolysis bullosa (autosomal recessive or dominant)

Y1 - MCD (38 decks)

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