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Principles > Genetics > Flashcards

Genetics Flashcards

1
Q

When does DNA replication occur?

A

During S - Synthesis phase

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2
Q

Mutation?

A

May or may not cause a disease

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3
Q

What is an acrocentric chromosome?

A

A chromosome in which the centromere is located quite near one end. They are number 13, 14, 15, 21 and 22

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4
Q

Aneuploidy vs Translocation

A

Aneuploidy is an extra or missing chromosome

Translocation is rearrangement of chromosome

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5
Q

What causes Down Syndrome

A

Extra chromosome 21, acrocentric chromosome

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6
Q

What is Robertsonian translocation?

A

Two acrocentric chromosomes stuck end to end

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7
Q

Edwards Syndrome

A

Trisomy 18

Small head, clenched fist, cleft lip or palate, toes may be clubbed or fused

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8
Q

Causes of the following -
Turners Syndrome
Triple X
Klinefelter Syndrome

A

Turners Syndrome - 45 X
Triple X - 47 XXX
Klinefelter Syndrome - 47 XXY

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9
Q

Which translocations have no effect on phenotype

A

Balanced translocations

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10
Q

What can large unbalanced dislocations result in?

A

Miscarriage

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11
Q

What is FISH used for

A

FISH - Florescent in Situ Hybridisation is used to detect and localize the presence or absence of specific DNA sequences on chromosomes

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12
Q

Microarray CGH

A

Array Comparative Genomic Hybridisation (aCGH)
Detects missing or duplicated chromosomes
However, many changes seen might be polymorphisms

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13
Q

What is mosaicism

A

Different individual cells have different genetic constitution

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14
Q

Polymerase Chain Reaction

A

Allows us to select one small piece of human genome and amplify it

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15
Q

Example of an enzyme used in PCR

A

Heat - resistant Taq Polymerase

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16
Q

What is missense mutation?

A

Type of point mutation in which a single nucleotide change results in a codon that codes for a different amino acid

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17
Q

What is post zygotic mutation

A

Mutation that occurs in the embryo

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18
Q

What is penetrance

A

The likelihood of having a disease if you have a genetic mutation

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19
Q

What is Achondroplasia caused by?

A

Achondroplasia is caused by a mutation in Fibroblast Growth Factor Receptor 3 (FGFR3)

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20
Q

Salient feature of autosomal dominant

A

Every generation is affected, 50% risk for children

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21
Q

Salient feature of autosomal recessive

A

Only one generation affected, 25% chance

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22
Q

X linked recessive inheritance

A

Carrier father, female offspring always carrier
Passes from female carrier to affected male to female
No male to male transmission

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23
Q

What are copy number variants

A

Sections of the genome are repeated and the number of repeats in the genome varies

24
Q

What is the common disease - common variant hypothesis

A

Thecommon disease-common varianthypothesis predicts that common disease-causingalleles, orvariants, will be found in all human populations which manifest a given disease. However these traits are neutral because many genes influence a trait

25
Q

How do we know there is a genetic contribution to disease

A

If the disease is more prevalent or higher risk in first degree relatives

26
Q

Which parents passes on mitochondrial DNA

A

Mother

27
Q

What is heteroplasmy

A

A cell can have some mutation in mitochondrial DNA and some that do not

28
Q

Weinberg hallmarks of cancer

A 
Evade apoptosis
Self-sufficiency in growth signals
Insensitivity to anti-growth signals
Tissue invasion and metastasis
Limitless replicative potential 
Sustained angiongenesis
29
Q

What are driver mutations

A

Mutations that drive carcinogenesis

30
Q

What are passenger mutations

A

Incidental mutations that happen because tumour is unstable

31
Q

What determines cancer characteristics, driver mutation or tissue of origin

A

Driver mutation

32
Q

All cancer cells have the same genetic makeup

A

False, most cancer cells are genomically unstable and have different genetic makeup

33
Q

What can be used for treatment of late stage melanoma

A

Vemurafenib

34
Q

Significance of HER2

A

Human epidermal growth factor receptor play an important role in development and progression of certain types of breast cancer. HER2 protein is an important biomarker and target of therapy

35
Q

Monoclonal antibody used to treat breast cancer

A

Trastuzumab (Herceptin), especially HER2 receptor positive

36
Q

What is the Philadelphia chromosome or Philadelphia translocation

A

Translocation of genetic material between chromosome 9 and 22. ABL-1 gene of 9 onto BRC gene of 22 coding for a tyrosine kinase causing the cell to divide uncontrollably.

37
Q

What can be used to treat leukemia that are Philadelphia chromosome positive and certain GI stromal tumours

A

Imatinib (Glivec)

38
Q

What is a mutator gene

A

A gene that increases the rate of mutation of one or more genes

39
Q

What are mismatch repair genes (MMR)

A

Genes that code for proteins capable of mechanisms to repair errors in repeat units of microsatellites. Errors in these can lead to genomic instability causing mutations

40
Q

How many % of women get breast cancer

A

Around 10%

41
Q

What can mutation in BRCA 1 lead to

A

Familial breast cancer

42
Q

What is symptomatic testing

A

Always test a symptomatic person first. If we identify a mutation in the parent we can offer the offspring a pre-symptomatic test

43
Q

Estimate the risk for daughter if mother with breast cancer at 70

A

Low risk

44
Q

Estimate the risk for daughter if mother and sister with breast cancer at 45

A

Medium risk

45
Q

Estimate the risk for daughter with BRCA-1 mutation

A

Low risk

46
Q

Drug used to treat pre and post menopausal women

A

Tamoxifen

47
Q

Screening for breast cancer

A

Mammography, breast examination

48
Q

Surgical intervention for breast cancer

A

Mastectomy and Oophorectomy

49
Q

Common disease - Common variant hypothesis

A

States common disease causing alleles or variants will be found in most of the population. Some of these variants lead to susceptibility to polygenic disease as each variant at each gene influences a disease by having additive effects on the disease phenotype. However, many genes influence a trait and these variants are neutral in part

50
Q

Common features of Mendelian disorders

A

Scary family history, young age, more people affected. These need to be identified whereas common disorders need to have risk estimated.

51
Q

How does symptomatic testing work

A

Genetic test the diseased family member. If mutation is found, we can confirm our diagnosis. Can also test other family members as part of presymptomatic testing. If no mutation found, treat on clinical parameters

52
Q

What is presymptomatic testing

A

Testing a patient who has a relative with a known mutation. If mutation is found, confirms patient will develop the disease.

53
Q

What is the Wolf-Hirschhorn Syndrome

A

Partial deletion of short arm of chromosome 4. Results in characteristic facial appearance, delayed growth, intellectual disability and seizures

54
Q

Huntington’s disease cause

A

CAG repeat encoding Poly-Glutamine. This has toxic effect on cells, neuronal loss

55
Q

The more CAG repeats you have, higher chances of developing Huntington’s early on

A

True

56
Q

How can genetic testing affect families negatively

A

Real implication for other family members, family/social issues, adoptions, family feuds

Principles (14 decks)

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