Fetal Abnormality Flashcards

1
Q

Human chromosome recognition methods

A
  • banding patterns with specific stains
  • length
  • position of centromere
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2
Q

function of telomere

A
  • protects end of the DNA

- prevents chromosomes from sticking together during division

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3
Q

types of aneuploidy

A
  • Down’s Syndrome (trisomy 21) = [47 XY +21]
  • Edward Syndrome (trisomy 18)
    = [47 XY +18]
  • patau syndrome (trisomy 13)
    = [47 XX +13]
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4
Q

X-chromosome disorders

A
  • 45 X Turner syndrome
  • 47 XXX Triple syndrome
  • 47 XXY Klinefelter syndrome
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5
Q

What is robersonian translocation

A

diagram

  • Philadelphia syndrom
  • translocation of 9 and 22
  • forms oncogene
  • Two acrocentric chromosomes stuck end to end
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6
Q

different elements of pharmacokinetics

A

Liberation
• Particle size and formulation

Absorption
• Bioavailability of the drug, route of administration, barriers

Distribution
• Barriers and volume of distribution

Metabolism
• Clearance, drug interactions

Excretion
• Clearance, routes of elimination

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7
Q

What is bioavailability?

A

how much of the drug is available for use (decreased bioavailability = decreased drug reaching target tissue = decreased pharmacological effect)

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8
Q

what are the factors that affect distribution

A
  1. Degree of drug ionisation
  2. Lipid solubility
  3. pH of compartments
  4. Cardiac output and blood flow
  5. Capillary permeability
  6. Plasma protein binding
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9
Q

What are the two phases of metabolism

A

phase I:

  • functionalisation (add/reveal a functional group) - key enzyme: cytochrome C
  • products often more reactive
  • generally oxidation, reduction or hydrolysis

phase II: conjugation (sulfate or glucuronide conjugation) –> make it more hydrophilic

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10
Q

define clearance

A

clearance = volume of the plasma cleared of the drug per unit time

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11
Q

define sensitivity

A

how well the test picks up having the disease

no. of results where disease detected in people w/disease/ no. of people with the disease

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12
Q

define specificity

A

how well the test detects not having the disease

no. of ‘normal’ results where the disease is not detected in people without the disease / no of people without the disease

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13
Q

Down’s syndrome screening

A

two stages to testing:

  1. screening test to find out if the baby has a high or low chance of having downs (offered up to 20 weeks)
  2. Diagnostic test to confirm whether baby has it (offered if screening showed high chance)
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14
Q

which screening tests are used

A

less than 14 weeks: blood test and nuchal translucency

14-20 weeks: blood tests only

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15
Q

What are the diagnostic tests

A
  1. transabdominal CVS - needle inserted into placenta
  2. transcervical CVS - small tube/forceps inserted through cervis
    or
    amniocentesis
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16
Q

Describe the phases of Meiosis I and II

A

Prophase I:
homologous chromosomes pair and form synapses

Prometaphase I:
The nuclear membrane disappears. One kinetochore forms per chromosome rather than one per chromatid, and the chromosomes attached to spindle fibers begin to move.

Metaphase I:

  • two chromosomes (four chromatids) align at the metaphase plate
  • (50-50 chance for the daughter cells to get either the mother’s or father’s homologue for each chromosome.)

Anaphase I:
Chromosomes, each with two chromatids, move to separate poles. = haploid daughter cells

Telophase I:
Nuclear envelopes may reform, or the cell may quickly start meiosis II.

Cytokinesis

17
Q

What are balanced and unbalances chromosome rearrangement

A

Balanced: all the chromosomal material is present

Unbalanced: extra or missing chromosomal material. Usually 1 or 3 copies of some of the genome

18
Q

What are the different oral routes of administration?

A

Buccal / sublingual mucosa
– Direct absorption into bloodstream
– Avoids first pass metabolism
– Not ideal surface for absorption

Small intestine
– Main site of drug absorption
– Large surface area, more neutral pH

Large intestine / colon
– Poor absorption, long transit times

Rectal mucosa
– Direct to systemic circulation

19
Q

What are the ways that small molecules cross the cell membrane?

A
  1. diffusion through lipid
  2. diffusion through aqueous channel
    . carrier
  3. pinocytosis
20
Q

Hydrophilic and lipophilic drug solubility

A

Hydrophilic drugs are soluble in aqueous, polar media.

Lipophilic drugs are soluble in fats and non-polar solutions.

21
Q

Where are the sites of metabolism?

A
– Gut lumen 
– Gut wall
– Plasma
– Lungs
– Kidneys 
– Nerves 
– Liver
22
Q

Cytochrome P450 enzymes functions

A
  • Biosynthesis of steroids, fatty acids and bile acids

* Metabolism of endogenous and exogenous substrates

23
Q

what are the factors that can affect metabolism?

A

Age
Genetic variation
Disease
Other medication

24
Q

Process of drug elimination

A

Drugs are eliminated either unchanged or as metabolites

• Hydrophilic drugs eliminated more readily than lipophilic drugs — Except the lungs

The kidneys are the most important organs involved in the elimination of drugs and their metabolites

25
Q

what are the different methods of transmission of organisms?

A
Person-person contact
Through food
Contaminated waste water
Insects
Fomites
26
Q

What are the three views about the status of the foetus?

A
  • It is a human being from the time of conception
  • It is a human being from the time of live birth
  • It is a human being from some other time
27
Q

Areas where the rights and interests of an adult woman outweigh those of a foetus

A

Abortion
Assisted reproduction
Pre-implantation genetic diagnosis

28
Q

What were the legislations that controlled abortion in the 20th century?

A
  • Offences Against the Person Act 1861 made performing an abortion or trying to self-abort carried a sentence of life imprisonment.
  • Abortion Act 1967 made abortion legal in England, Scotland and Wales up to 28 weeks gestation
  • Human Embryology and Fertilisation Act 1990 reduced term to 24 weeks gestation
29
Q

The terms of abortion

A

• Two registered medical practitioners
• The pregnancy has not exceeded its twenty-fourth week and risk of
injury to the physical or mental health of the pregnant woman or any
existing children of her family; or
• Necessary to prevent grave permanent injury to the physical or
mental health of the pregnant woman; or
• Continuance of the pregnancy would involve risk to the life of the
pregnant woman; or
• Substantial risk that if the child were born it would suffer from such
physical or mental abnormalities as to be seriously handicapped.

30
Q

What are the ethical considerations in screening for Down’s Syndrome?

A
Non-maleficence 
Beneficence
Health maximisation 
Efficiency
Respect for autonomy
Justice
31
Q

What are the potential benefits and harms of screening?

A
Benefits: 
• Reduced disease incidence (?) • Reduced disease mortality
• Earlier, less radical treatment 
• Cost-effective
• Overall population benefit
Harms: 
• False reassurance
• Over-investigation and treatment
• Anxiety
• Longer period of morbidity with unaltered prognosis
• Harm from screening test
• Opportunity costs
• Increased health inequalities
32
Q

What are the challenges with optimising coverage?

A
  • Change of address
  • Migrants
  • Travellers
  • Prisoners
  • Students
  • Trafficked people
33
Q

What could cause inequalities in terms of how screening programmes are run?

A
  • Identifying and inviting screening cohort
  • Acceptability of the test
  • Failure to make reasonable adjustments
  • Poor communication about the test results or the next steps in the programme
  • Prejudice leading to poor care
34
Q

what are the challenges with optimising uptake?

A
  • Communication
  • Health literacy
  • Deprivation
  • Accessibility
  • Vulnerable groups
  • Minority ethnic groups