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Phase 3 > Genetics > Flashcards

Genetics Flashcards

1
Q

What is the biggest cause of trisomies?

A

Maternal Dis-junction - failure of normal chromosomal separation

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2
Q

What is Trisomy 13? and name some symptoms:

A

Patau Syndrome

congenital heart disease - 50% die before 1 month

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3
Q

What is trisomy 18?

A

Edward’s syndrome

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4
Q

What kind of tumor suppressor is the BRCA gene?

A

Stability Gene

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5
Q

What is the main function of BRCA genes?

A

To code for homologous DNA repair for double stranded breaks

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6
Q

What two less common genes are associated with breast and ovarian cancer?

A

MLH1

MLH2

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7
Q

What is a prophylactic drug being used to treat ovarian cancer?

A

Aloparib

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8
Q

Hereditary Non - polyposis Colon cancer is most commonly caused by which genes?

A

MLH1

MSH2

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9
Q

Familial Adenomatous Polyposis is most commonly caused by which genes?

A

APC gene on chromosome 5.

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10
Q

What non -clinically significant symptom may a patient with familial adenomatous polyposis have?

A

Congenital hypertrophy of the retinal pigmented epithelium

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11
Q

Name a autosomal recessive cancer:

A

MYH Polyposis

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12
Q

What does the MYH gene code for?

A

Base excession repair

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13
Q

In Huntington’s disease, which gene is affected and what is the cause of pathology?

A

HHT gene.

CAG repeats - glutamine build up n the protein leading to aggregates forming.

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14
Q

Defects in DMPK gene will cause which disease?

A

Myotonic dystrophy

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15
Q

In myotonic dystrophy, what gene is affected and how does this cause pathology?

A

DMPK gene.

3’ CTG repeats - causing faulty DMPK mRNA.
This indirectly causes toxic affect on the splicing of other mRNA.

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16
Q

Name an important mRNA that is indirectly affected by DMPK -causing characteristic myotonia

A

CLCN-1 mRNA

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17
Q

What is the most common gene mutation in CF?

A

F508 deletion

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18
Q

What protein does DMD code for?

A

Dystrophin - an intracellular protein that attaches to the dystroglycoprotein complex and the actin filament - communicating with extracellular of cell

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19
Q

Whats the most common mutation in DMD and what does this cause that leads to such severe symptoms being seen?

A

Deletion of exons in the DMD gene, causing frame shifting, causing complete protein dysregulation .

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20
Q

Whats implicated in FMR1 gene?

A

Fragile X - syndrome

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21
Q

How is Fragile X syndrome developed?

A

tri-nucleotide repeats at the 5’ end of FMR1 gene.

resulting in silencing of the gene - through methylisation

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22
Q

What type of sequencing would be done to search for a point mutation in an unknown gene defect?

A

Sangers sequencing

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23
Q

What type of sequencing is done for a point mutation of known allele? i.e. the mutation is known.

A

ARMS sequencing

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24
Q

What time of testing is done for a sub-microscopic mutation, where the gene allele is not known? and how is it interrupted?

A

aCGH

Green: duplication
Red: deletions

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25
Q

What type of testing is done for a sub-microscopic mutation, where the gene allele is known?

A

MLPA

26
Q

With regards to genetic testing what does PGD mean and what are some pros and cons?

A

Pre- implantation diagnosis

Pros:
- allows implantation of unaffect cells

Cons:

  • Not available to all women
  • long wait
  • 50% take home baby rate
27
Q

What are polyploidies? and give an example:

A

Abnormal number of chromosomes in a multiple of 23.

Triploidy: 69 chromosomes

this can occur in hydatidiform changes, where 2 sperm penetrate an egg, resulting in 69 chromosomes.

28
Q

What syndrome can FISH be useful for identifying?

A

Williams Syndrome

29
Q

Name some neonatal screening tests carried out Mass spectrometery:

A

PKU

MCADD

30
Q

Name the set of conditions that show genetic anticipation:

A

Huntington’s
Myotonic dystrophy
Fragile X syndrome (to a degree)

31
Q

What drug re-opens the Cl- channel in CF, which is a type of precision medicine? what is the mutation it specifically works on?

A

Ivacaftor

G551D

32
Q

What gene has been cut out using CRISPR CAS9 and what disease does it cause?

A

FBN1 - marfan’s syndrome

33
Q

Which drug targets the HER2 - EGFR2 receptor?

A

Trastuzumab

34
Q

The new therapy proposed for DMD is what?

A

Antisense oligonucleotide therapy

  • causes exon skipping to create an inframe mutations - less severe than normal DMD out of frame mutations.
35
Q

Name some autosomal recessive conditions:

A

Cystic Fibrosis

PKU

Spinal Muscular Atrophy

Congenital adrenal hypoplasia

36
Q

In an X-linked recessive condition, what would you expect the disruption to be amongst males and females from a female carrier?

A

50% daughters carriers

50% sons affected

37
Q

Name some X-linked dominant conditions:

A

Vit D deficiency

Rett syndrome

Incontinentia pigmenti

38
Q

In which type of pattern of inheritance would you expect to see higher rates of females affected?

A

X-linked dominant

39
Q

What is the disease, that is a mitochondrial disease leading to lack of ATP synthesis, and what is the gene?

A

Leigh’s disease

MT-ATP6 gene

40
Q

Which chromosome is HER2 gene found on? and what is a good analysis tool for looking at it?

A

chromosome 17

FISH

41
Q

Which disease shows genetic anticipation if the mother is a carrier?

A

Myotonic dystrophy

42
Q

What is some of the symptoms of neurofibromatosis?

A

Cafe au lait macules

neurofibromas

30% having learning difficulties

43
Q

List the trinucleotide repeat disease:

A

Huntington’s

  • CAG - glutamine
  • anticipation from father
  • AutoD

Mytonic Dystrophy

  • CTG
  • Anticipation from mother
  • AutoD

Fragile X

  • CCG
  • anticipation
  • x-linked
44
Q

What’s the blood markers carried out for carriers and children who have duchene muscular dystrophy?

A

Serum Creatinase Kinase

45
Q

What’s the sign called when a child has to use their hands on their knees to push themself up?

A

Gowen’s sign

46
Q

List some comparisons between autosomal dominant and autosomal recessive conditions:

A

Vertical vs Horizontal

Homozygous vs heterozygous

50% vs relatively low risk depending on population risk

Variable expression vs Constant expression

Incomplete penetrance vs Complete penetrance

47
Q

Define what a Point mutation is:

A

Single change in the nucleotide sequence

48
Q

Define what a missense mutation is:

A

Point mutation in which the single nucleotide change results in codon that codes for a different amino acid.

49
Q

Define what a silent point mutation is:

A

Where the single nucleotide change codes for the same amino acid

50
Q

What is a conservative point mutation?

A

Where a point mutation leads to a different amino acid being produced, but is very similar to original amino acid.

51
Q

Define what a Nonsense mutation is?

A

Were a premature stop codon is formed - causing premature termination of protein synthesis.

52
Q

What is the symptoms of fragile x syndrome?

A

It is the most common cause of mendelian inheritance to cause mental impairment

Low IQ 
Inverted ears 
Mitral prolapse 
long facial features 
enlarged testicles
53
Q

Variable expression may occur in AS dominant conditions, what is it that causes this?

A

Variable expression is where there is different severities of the disease.

It may be caused by:

  • stability genes
  • epigenetics
54
Q

How is Cystic fibrosis screened for?

A

Immunoassay

Cl- levels in sweat of the baby.

If these are positive then DNA testing is done.

55
Q

If a person has myotonic dystrophy, they are at greater risk of developing another disease, what is this and why?

A

Diabetes and this is because of damage to the mRNA that codes for the insulin

56
Q

What is a very good test for detecting gene deletions?

A

MLPA

*the area must be known

57
Q

What is a very good test for detecting trisomy?

A

QF - PCR

58
Q

Mutated Proto-oncogenes are usually not inherited, name one that is and what it is associated with:

A

RET

MEN2 - pheochromocytoma

59
Q

What area on the x chromosome is dystrophin coded, and thus is mutated in DMD patients?

A

Xp21

60
Q

What drug is good for stopping colorectal cancer?

A

Aspirin

61
Q

What serious trisomy is associated with an extra little finger?

A

Patau syndrome - trisomy of 13

Phase 3 (50 decks)

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