Brainscape's Knowledge GenomeTM

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


See full index

year 2 > Congenital defects and their scientific basis > Flashcards

Congenital defects and their scientific basis Flashcards

1
Q

What does congenital mean?

A

Present at birth- does not necessarily mean that it occurred before birth.

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

What is phenotype?

A

Physical characteristics which are observable

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

What is genotype?

A

Genetic makeup of an individual

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

What are the types of abnormal morphogenesis?

A

Deviation of body structure from the norm
->Disturbance
->Disruption
->Malformation

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

What is a deformation?

A

Late stage abnormality during normal development due to later stage mechanical forces which reduce foetal movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is disruption?

A

Disruption in normal morphogenesis because of early influence from external factors that are destructive such as teratogens or infections.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is malformation?

A

Primary disturbance of embryogenesis which is established as abnormal due to genetics and/or environment so no normal development occurs.

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

How are congenital abnormalities classified?

A

Based on the aetiology and the timing of the issue.
-> Is it disruption/disturbance/malformation/Sequential issue?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a sequential anomaly?

A

Primary error with a cascade of events and consequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the cause of a majority of congenital defects?

A

Majority of congenital defects are unknown
Of the known, majority are polygenic, the interaction of multiple genes. Lesser are single gene and chromosomal defects

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

What is a primary anomaly?

A

Abnormality in morphogenesis due to mutation of a single gene, chromosome or polygenic issue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a secondary anomaly?

A

Abnormality in morphogenesis due to external factors such as a teratogen or an infection

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

What are the teratogens?

A

->Infections such as:
Toxoplasmosis, Rubella, Cytomegalovirus, Herpes, Varicella, Parvovirus

->Drugs/medications such as Vitamin A, alcohol and medication
->Maternal diabetes mellitus

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

Why is Vitamin A harmful in pregnancy?

A

Excess Vitamin A, such as in retinoids can lead to malformations such as spina bifida in the foetus, cleft palate and deformities in the limbs.

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

What are the early effects of teratogens in embryo at 2-4 weeks gestation?

A

Abnormality affecting a single cell or gene will present in many different body areas- this is a polytropic defect

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

What are the late effects of teratogens in embryo at 4-8 weeks gestation?

A

Localised defect which affects only a sub-population of cells- this is a monotropic defect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the effects of teratogens in the foetal stage?

A

Affects organogenesis of specific tissues and organs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What affects teratogenic susceptibility in pregnancy?

A

Stage of development- embryonic stage has the greatest susceptibility due to cells and systems not being formed/very immature, and this wide-range susceptibility is very low in foetal stage for all tissues except the CNS. CNS remains susceptible to teratogens throughout pregnancy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What stage of pregnancy has the most adverse outcomes of teratogens?

A

Pre-embryonic stage from fertilisation to 2nd week which is driven by zygote replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are examples of congenital abnormalities caused by deformation?

A

Abnormality of body due to mechanical force:
-> Talipes
-> Congenital hip deformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is talipes?

A

Achilles tendon is shorter that causes the feet to turn inwards, due to intrauterine growth restriction where the baby was too large or low levels of amniotic fluid. This is a type of deformity.

22
Q

What is congenital hip deformation?

A

Congeital dislocation of ball and socket joint because of low amniotic fluid or vaginal birth in the breech position. This is a type of deformity.

23
Q

What are the examples of congenital abnormalities caused by disruption?

A

External destructive factors interrupt normal morphogenesis
->Amniotic bands
->Poland anomaly

24
Q

What is an amniotic band?

A

Amniotic membrane is torn or ruptured and wraps around the digit/limb of the foetus, resulting in constricted blood supply and loss of the affected body part. This is a type of disruption.

25
Q

What is a Poland anomaly?

A

Interruption of the subclavian artery which leads to unilateral underdevelopment/absence of the pectoralis muscle. This is a type of disruption.

26
Q

What are the examples of congenital abnormalities caused by seuqential issues?

A

Primary error with a cascade of events and consequences.
-> Potter Sequence
->Pierre-Robin sequence

27
Q

What is a Potter Sequence?

A

Condition where there is renal agenesis that causes low amniotic fluid. This increases in utero pressure and causes foetal compression and reduces foetal urine excretion.

Low amniotic fluid means less fills the lungs during development, leading to pulmonary hypoplasia.

28
Q

What is a Pierre-Robin sequence?

A

Mandibular hypoplasia, meaning the tongue is too large for the mouth that leads to upper airway obstruction and prevention of secondary palates developing.

29
Q

What is Di-George syndrome?

A

Genetic condition caused by the deletion of a region in chromosome 22 for the TBX-1 developmental gene. This is important for the development of pharyngeal pouches 3 and 4 for the thyroid and parathyroid gland and thymus.

30
Q

What does the 3rd pharyngeal pouch give rise to?

A

Thymus and inferior parathyroid gland.

31
Q

What does the 4th pharyngeal pouch give rise to?

A

Superior parathyroid.

32
Q

What is the presentation of Di-George syndrome?

A

Underdeveloped thymus causes hormonal disturbances due to hypoparathyroidism, feeding problems, immunological disturbances because of less T cell production and speech delays.

CATCH 22:
Cardiac abnormality
Abnormal face
Thymus undervelopment
Cleft palate
Hypocalcaiemia/Hypoparathyroidism
22: deletion of chromosome 22

33
Q

What is Charge syndrome?

A

Multi-organ system abnormality caused by a heterozygous mutation in the CH7 gene (chromodomain helicase DNA-binding protein 7) which regulates chromatin remodelling and essential for formation of multipotent neural crest cells.

34
Q

What are neural crest cells?

A

Involved in embryological development of the nervous system and give rise to the PNS (cranial nerves) facial skeleton and the smooth muscle, cartilage and connective tissue.

35
Q

What is the precursor to the CNS?

A

Neural tube.

36
Q

What is the presentation of CHARGE syndrome?

A

Absence of CHD7 gene leads to issues with the development of the head and neck, heart and adrenal medulla

C- coloboma (defect in iris)
H- Heart defect
A- Atresia of Choana which narrows nasal airways
R- Retardation of growth and development
G- Genital hypoplasia
E- Ear defect

37
Q

What is spina bifida?

A

Defect in the closure of the caudal neuropore, commonly occurring in the lumbosacral region. This creates structural abnormalities in the brain which prevents proper drainage of the CSF, causing hydrocephales.

38
Q

Why does spina bifida occur?

A

Occurs due to a combination of genetic predisposition and environmental factors such as deficiency in folic acid, worsened by anti-epileptic drugs.

It typically occurs in the lumbosacral region.

39
Q

What are the types of spina bifida?

A

Meningoceles: Gap in the vertebrae that allows a sac of fluid contaninig the mater and CSF to be extruded.

Myelomeningoceles: Gap in the vertebrae that allows a sac of CSF containing the meninges (mater) and neural/spinal elements to be extruded, leading to nerve underdevelopment.

40
Q

What is hydrocephales?

A

Abnormal build of up cerebrospinal fluid in the brain ventricles

41
Q

What is the consequence of alcohol intake in pregnancy?

A

Neural crest cells are sensitive to alcohol and results in lower migration. This leads to improper formation of the facial skeleton because it derives from neural crest cells of the pharyngeal arches. Causes short nose, flat midface, small eye opening and low nasal bridge.

42
Q

What is congenital rubella syndrome?

A

Maternal infection with rubella virus which causes necrosis of chorionic epithelia and inhibits mitosis and development of precursor cells. Leads to microencephaly (incomplete brain development), cloudy patches in the eye called cataracts and patent ductus arteriosus

43
Q

What are the impacts of congenital abnormalities?

A

It accounts for 3% of neonatal deaths worldwide. Causes perinatal and neonatal death and disability, emotional and financial costs and there are historical beliefs of causation.

44
Q

What is the most common cause of neonatal death?

A

Pre-term birth complications or intrapartum complications.

45
Q

What is the most common cause of death in children?

A

Diarrhoea and pneumonia.

46
Q

What form of screening for conditions can be carried out before conception?

A

Genetic counselling to investigate risk of genetic disorders.

47
Q

What are the screenings in the first trimester?

A

Triple test for Down’s syndrome, Patau’s syndrome and Edward’s syndrome.
Nuchal fold assessment

48
Q

What is the Nuchal fold assessment?

A

Fold at the back of the foetal neck used to identify trisomy 21 in Down’s syndrome

49
Q

What are the screenings in the second trimester?

A

At week 20, there is an anomaly scan for the structures of the foetus and the placenta.

50
Q

How is a diagnosis made?

A

Physical examination, family history and diagnostic tests with radiology and genetic analysis.

51
Q

What is the impact of congenital rubella infection?

A

Affects the development of the special sense organs, causing hearing impairments and cataract formation. It affects the heart by causing patent ductus arteriosus.

year 2 (247 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions