Introduction - the basics Flashcards

1
Q

What is molecular genetics?

A

The study of structure and function of individual genes.

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2
Q

What is clinical genetics?

A

The application of genetics to diagnosis and patient care.

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3
Q

How are genetic disorders tested for?

A
Cytogenetics
MLPA tests
Karyotype
X-rays
Blood tests
...
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4
Q

What mutations in genes involved with ENaC (Na channels) lead to?

A

Hypertension.

-involved in renal salt balance

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5
Q

Mutations in what genes are associated with type 1 diabetes?

A

Glucokinase transcription factors.

-pancreatic beta cells

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6
Q

What gene mutations are associated with idiopathic epilepsy and migraines?

A

Ion channels.

-e.g. KCNj10

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7
Q

What can ASPM gene mutations lead to?

A

Abnormal head size.

-e.g. microcephaly

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8
Q

Name some genes associated with monogeneic autoimmune disorders.

A

AIRE
TREX1
RNAseH2

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9
Q

What is a Gefitinib?

A

1st selective inhibitor of EGFR.

  • used to treat certain cancers (e.g. NSCLC)
  • more effective in some patients
  • France screen patients for EGFR mutations
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10
Q

What’s the difference between pharmacogenomics and pharmacogenetics?

A

PHARMACOGENOMICS - analysing entire genomes (groups of people) to identify genetic factors influencing drug responses
-more population based

PHARMACOGENETICS - studying individual’s genetics to predict drug responses
-more individual based

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11
Q

What is Gleevec used to treat?

A

Chronic myeloid leukaemia (CML).

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12
Q

What genetic mutation causes chronic myeloid leukaemia?

A

Translocation (9;22).

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13
Q

What is the fusion gene called in chronic myeloid gene?

A

BCR/abl gene.

  • abl gene (chr 9)
  • BCR gene (chr 22)
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14
Q

What chromosome contains the BCR/abl gene in chronic myeloid leukaemia?

A

Philadelphia chromosome.

-chr 22

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15
Q

What are the main 3 categories that contribute to the aetiology of disease?

A
  • Environment
  • Single gene
  • Polygenic
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16
Q

What causes achondroplasia (dwarfism)?

A

Single gene mutation.

-FGFR3

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17
Q

What is the main similarity between the following:

  • Duchenne muscular dystrophy
  • Haemophilia
  • Phenylketonuria?
A

Mainly caused by genetics rather than environment.

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18
Q

What is the main similarity between the following:

  • Scurvy
  • TB?
A

Mainly caused by environment rather then genetics.

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19
Q

What does multifactorial / complex mean?

A

Interaction of multiple genes and environmental factors.

-e.g. type II diabetes, IHD

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20
Q

What type of genetic disorders have Mendelian inheritance?

A

Single gene disorders.

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21
Q

What is a chromosomal genetic disorder?

A

Imbalance / rearrangement in chromosomal structure.

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22
Q

Give examples of chromosomal mutations. (3)

A
  • Aneuploidy
  • Deletion
  • Translocation
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23
Q

What are somatic mutations?

A

Mutations within a gene in a defined population of cells that results in disease.
-e.g. breast cancer

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24
Q

What are the main single gene modes of inheritance? (4)

A
  • Autosomal dominant
  • Autosomal recessive
  • X-linked
  • Mitochondrial
25
Q

What structures does autosomal dominant inheritance normally affect? (3)

A
  • Structural proteins
  • Receptors
  • Transcription factors
26
Q

What is the main similarity between Marfans and Huntington disease?

A

Both autosomal dominant inheritance.

27
Q

What is penetrance?

A

The frequency that a genotype is expressed by those individuals that possess it (%).

28
Q

Give an example of penetrance altering with age.

A

Huntington disease.

-100% penetrance by 80yrs

29
Q

What is incomplete penetrance?

A

When not all relatives who inherit the mutation develop the disorder.
(e.g. BRCA1&raquo_space; breast cancer)

30
Q

What is expressivity?

A

Variation in expression.

-the extent to which a heritable trait is present

31
Q

What is anticipation?

A

Symptoms of a genetic disorder becoming apparent at an earlier age (and more severe) as passed from one generation to the next.
-e.g. Huntington’s

32
Q

When does a new dominant / de novo mutation occur?

A

During gametogenesis / early embryonic development.

33
Q

Can de novo mutations be passed on?

A

Yes, parents of the affected individual do not have them, but they can be passed on to offspring.

34
Q

What can increase the risk of autosomal recessive inheritance?

A

Consanguineous relationship.

35
Q

Name some disorders with autosomal recessive inheritance. (4)

A
  • Cystic fibrosis
  • Haemachromatosis
  • Sickle cell disease
  • Metabolic disorders
36
Q

Can you have male-male transmission of X-linked disorders?

A

No.

37
Q

Name some disorders with X-linked inheritance. (4)

A
  • Duchenne musclar dystrophy
  • Fragile X syndrome
  • Haemophilia
  • Red/green colour blindness
38
Q

What are the outcomes is the mother is a carrier of an X-linked disorder?

A

25% normal girl
25% carrier girl
25% normal boy
25% affected boy

39
Q

What are the outcomes is the father is a affected with an X-linked disorder?

A
  • All daughters are carriers

- All sons are unaffected

40
Q

What are the 2 main factors influencing phenotype of female X-linked disorder carriers?

A
  • X inactivation
  • XL dominant vs XL recessive inheritance

> > variable phenotype

41
Q

What is another term for x-inactivation?

A

Lyonisation.

42
Q

What is x-inactivation?

A

Random inactivation of one of the X chromosomes in female cells.
-more than 1 x chromosome

43
Q

When does x-inactivation occur?

A

Early embryogenesis.

-remains inactive throughout lifetime of cell

44
Q

How can x-inactivation affect x-linked female carriers?

A

Inactivation of normal X chromosome&raquo_space; significant phenotype.
-e.g. fragile X syndrome

45
Q

What is Rett syndrome?

A

Disorder of brain development.

  • X linked dominant
  • lethal in males, phenotype only in females
46
Q

Give 2 examples of mitochondrial inheritance.

A

Maternally inherited diabetes and deafness.

47
Q

How are males and females affected by mitochondrial inheritance?

A

Males and females affected equally.

48
Q

How many genes are present in motichondrial DNA?

A

27 genes.

49
Q

What is the inheritance pattern of mitochondrial inheritance?

A
  • Affected mother&raquo_space; affected children

- Affected father&raquo_space; unaffected children

50
Q

FAMILY TREE :

what are the symbols for genders?

A
Male = square
Female = triangle
Unspecified = diamond
51
Q

FAMILY TREE :

what does a double line joining a couple mean?

A

Consanguineous.

52
Q

FAMILY TREE :

what does a line through a symbol mean?

A

Person has died.

53
Q

FAMILY TREE :

what does a shaded centre mean?

A

Carrier of x-linked recessive disorder.

54
Q

FAMILY TREE :

what does a half shaded symbol mean?

A

Heterozygous for autosomal recessive disorder.

55
Q

FAMILY TREE :

what does a shaded symbol mean?

A

Affected individual.

56
Q

FAMILY TREE :

what is the symbol for a stillborn baby?

A

Diamond with a line through and SB next to it.

57
Q

FAMILY TREE :

what is the symbol for a therapeutic abortion?

A

Triangle with a line through.

58
Q

FAMILY TREE :

what is the symbol for a spontaneous abortion / miscarriage?

A

Triangle.