Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Block 5 > Congenital Birth Defects & Teratology > Flashcards

Congenital Birth Defects & Teratology Flashcards

1
Q

What abnormalities can be present at birth?

A
  1. Malformation: misformed
  2. Deformation: formed then affected
  3. Dysplasia: expansion of immature cells
  4. Disruption: normal process e.g. cell migration is disrupted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What causes human birth defects in order of decreasing commonality?

A 
UNKNOWN
Multifactorial inheritance
Environmental agents (drugs/viruses)
Mutant genes 
Chromosomal abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is teratogenesis?

A

Process whereby abnormality is induced in a developing organism during uterine life by foreign agents called teratogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is teratogenesis associated with?

A 
Chemicals/pollutants/radiation
Alcohol
Dietary intake
Viruses
Medication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What influences the teratogenicity of a substance?

A
  1. It must contact embryo/foetus
  2. Period of development at exposure
  3. Exposure-time + dosage
  4. Foetus genotype influences susceptibility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the common teratogens?

A
  1. Alcohol > foetal alcohol syndrome
  2. Vitamin A > cleft palate, mandibular hypoplasia + heart defects
  3. Rubella/HSV > deafness, cataracts, retinal dysplasia+ microcephaly
  4. X-ray > microcephaly, spina bifida + cleft palate
  5. Valproate > neural tube defects, facial defects + limbs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the symptoms of foetal alcohol syndrome (FAS)?

A 
Midline facial abnormalities via maxillary hypoplasia:
No philtrum
Thin top lip
Heavy epicanthic folds
Flattened nose

Mental/neural retardation (behavioural/developmental)
Heart defects
Short palpebral fissure
Heart defects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What infection agents are teratogens?

A
  1. Rubella > cataracts, cardiac defects + deafness
  2. Cytomegalovirus > microcephaly + microphthalmia
  3. Toxoplasma gondii > microcephaly, microphthalmia + hydrocephaly
  4. Syphilis > stillbirth + miscarriage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What environmental factors are teratogens?

A
  1. Ionising radiation (mainly affects)
  2. X-rays
  3. Pesticides, herbicides + fungicides
  4. Pollutants e.g. heavy metals + chemical effluent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How common is teratogen exposure?

A

Pregnant women take on average 4 drugs exc. nutritional supplements per pregnancy - 40% of these in critical period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are pregnant women exposed to teratogens most commonly?

A
  1. Drugs used prior to pregnancy knowledge e.g. pain killers
  2. Drugs necessary for condition independent of pregnancy e.g. anti-epileptics
  3. Drugs necessary due to pregnancy specific condition e.g. thalidomide, diethylstilbestrol
  4. Environmental agents impossible to avoid e.g. crop sprays
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How could many birth defects be prevented?

A

Appropriate avoidance or supplementation of nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the common nutritional causes of congenital malformation?

A

Folate deficiency
Zinc (low OR high)
Glucose/ketone bodies from diabetic condition
Retinoid excess

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When is the embryo/foetus most at risk of damage?

A

Weeks 3-8 (weeks 9-14 carries less risk but still susceptible) as core systems are developing by processes like cell division, organogenesis and midline union but also before the women knows she is pregnant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If problems occur at weeks 14-38 what defect commonly occurs?

A

Functional NOT structural where there is a direct toxic effect on cell of embryo that is either lethal or reduces growth e.g. retardation of mental development in FAS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When is sub-lethal damage repaired during pregnancy?

A

Weeks 1-2 as this is the pre-differentiation stage

17
Q

What are Wilson’s 6 general principles of teratology?

A
  1. Final manifestations are death, malformation, growth retardation or functional disorder
  2. Susceptibility varies with developmental stage at exposure time
  3. Agents act in specific way on developing cells/tissues to initiate abnormal embryogenesis
  4. Manifestations increase in degree from no-effect to totally lethal as dose increases
  5. Access of adverse environmental influences to developing tissues on nature of agent
  6. Susceptibility depends on genotype of foetus and manner that it interacts with environmental factors
18
Q

How can a substance be teratogenic?

A
  1. Mutation to DNA sequence
  2. Interruption of DNA/RNA synthesis
  3. Failure of normal cell migrations
  4. Chromosomal abnormalities causing structural/quantitative DNA
  5. Interference with cell differentiation
  6. Failure of normal cell-to-cell interactions
19
Q

What teratogens can cause limb abnormalities?

A
  1. Thalidomide (anti-nauseant + sleeping pill)
  2. Retinoids (vit A derivatives)
  3. Mechanical issue via strangling of tissue by amniotic bands
20
Q

What limb abnormalities exist?

A 
Amelia: lack of limb
Meromelia: part of limb
Phocomelia: seal limbs
Polydactyly: extra digits
Syndactyly: webbed digits
21
Q

What cardiac defects exist?

A

Ventricular-septal (can be neural crest cell associated)
Tetralogy of fallot
Transposition of great vessels

22
Q

What is the common cause of cardiac defects?

A

Alcohol

23
Q

What neural tube defects exist?

A

Spina bifida: meningocele +
myeloshisis (more severe)
Ancephaly: major portion of brain/skull missing
Sensory system defects of eye/ear

24
Q

What are the causes of neural tube defects?

A

Multiple teratogens but folic acid deficiency commonly

25
Q

What facial defects exist?

A
  • Cleft palate (mainly female)/lip (mainly male) from abnormal neural crest cell migration (so often acc. with reduced brain size and cardiac defects)
  • Macroglossia/macroglossia
  • Treacher-Collins
  • Pierre Robin syndrome
  • Mandibulofacial maldevelopment/dysostosis (zygoma, mandible + maxilla)
  • Downslanting palpebral fissure
  • Malformed ears + possible conductive deafness
26
Q

What are the causes of facial defects?

A
  • Multiple teratogens e.g. anti-seizure drugs, retinoids and corticosteroids
  • Maternal diabetes
  • Autosomal dominant inheritance e.g. Treacher-Collins syndrome
27
Q

How can you help mothers avoid teratogenicity?

A

Advice pre-conception regarding nutritional and lifestyle and avoid prescribing where possible or if its necessary prescribe safest and minimal therapeutic dose

28
Q

What are the classifications of teratogens?

A

A: not shown to increase risk
B: animal studies not shown increased risk but no human studies
C: animal studies show adverse effects but no human studies e.g. Fluconazole
D: medication associated with defect in humans but may have benefits that outweigh risk e.g. ACE inhibitor/ARB
X: should not be used in human pregnancy e.g. Androgens

29
Q

Give some examples of teratogenic drugs in class D.

A 
ACE inhibitors
Angiotensin II receptor antagonists
Antineoplastic alkylating agents 
Aminoglycosides
Aspirin 
Atenolol 
BZDs
Carbazepine 
Lithium 
Penicillamine 
Barbiturates 
Tamoxifen 
Tetracycline
30
Q

Give some examples of teratogenic drugs in class X.

A 
Androgens
Antineoplastics (antimetabolites e.g. folic acid antagonists)
BZDs
Progestins
Raloxifene
Statins
Thalidomide
Warfarin
31
Q

Give some examples of teratogenic drugs in class C.

A

Corticosteroids

Fluconazole

Block 5 (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions