Congenital Birth Defects

Question 1

What does congenital mean?

Answer 1

Present at birth

Question 2

What is an anomaly?

Answer 2

A structural deviation from the norm

Question 3

Define genotype.

Answer 3

The genetic constitution of an individual.

Question 4

Define phenotype.

Answer 4

Observable traits resulting from the genotype.

Question 5

When do congenital anomalies occur?

Answer 5

When normal embryonic development is disrupted.

Question 6

What is a malformation?

Answer 6

A primary error in embryonic development—”made wrong”.

Question 7

What is a disruption?

Answer 7

A normal structure that goes wrong due to an external factor.

Question 8

What is a deformation?

Answer 8

A structure that was normal but got distorted (mechanical pressure).

Question 9

What is a sequence in congenital defects?

Answer 9

One defect causes a cascade of related problems.

Question 10

What are the 3 primary genetic causes of congenital anomalies?

Answer 10

Single gene defects, chromosomal abnormalities, polygenic inheritance.

Question 11

Name 4 teratogenic causes of congenital anomalies.

Answer 11

Infections, drugs/pollutants, maternal disease (e.g. diabetes), radiation.

Question 12

What is a teratogen?

Answer 12

An external agent that can disturb the development of the embryo or fetus.

Question 13

Name a congenital infection that causes anomalies.

Answer 13

Rubella (Congenital Rubella Syndrome).

Question 14

What happens if a teratogen affects the embryo in the pre-embryonic stage (0–2 weeks)?

Answer 14

Usually results in lethal effects.

Question 15

When is the embryo most sensitive to teratogens?

Answer 15

During the embryonic period (2–8 weeks).

Question 16

What are early (2–4 weeks) teratogenic effects called?

Answer 16

Polytopic field defects (widespread impact).

Question 17

What are later (4–8 weeks) effects called?

Answer 17

Monotopic field defects (localized impact).

Question 18

What causes DiGeorge Syndrome?

Answer 18

22q11.2 deletion, affecting pharyngeal pouch development.

Question 19

What does DiGeorge Syndrome commonly affect?

Answer 19

Thymus, parathyroids, heart, facial features.

Question 20

What gene is mutated in CHARGE syndrome?

Answer 20

CHD7 gene.

Question 21

What does CHARGE stand for?

Answer 21

C – Coloboma
H – Heart defects
A – Choanal atresia
R – Retardation (growth/development)
G – Genital anomalies
E – Ear defects

Question 22

What causes spina bifida?

Answer 22

Failure of caudal neural tube closure.

Question 23

Where do most neural tube defects occur?

Answer 23

Lumbosacral region.

Question 24

What often coexists with spina bifida?

Answer 24

Hydrocephalus.

Question 25

What contributes to neural tube defects?

Answer 25

Genetics, environment, maternal nutrition (e.g. folate).

Question 26

Is any level of alcohol safe during pregnancy?

Answer 26

No—no safe level is known.

Question 27

What cells are affected in FAS?

Answer 27

Neural crest cells and the developing brain.

Question 28

How common are FAS and alcohol-related defects?

Answer 28

About 1 in 100 births.

Question 29

What does congenital rubella affect?

Answer 29

Heart, special senses, and other organs.

Question 30

What percentage of liveborn infants have congenital anomalies?

Answer 30

Around 3%.

Question 31

How much do congenital anomalies contribute to tertiary admissions?

Answer 31

20–30%.

Question 32

What are some cultural misconceptions about congenital anomalies?

Answer 32

Attributed to supernatural causes in some cultures.

Question 33

What is done before conception to reduce risk?

Answer 33

Genetic counselling.

Question 34

What is included in first-trimester screening?

Answer 34

Triple test, nuchal fold measurement.

Question 35

What is the key second-trimester screening tool?

Answer 35

20-week anomaly scan (USS).

Question 36

What is a primary anomaly?

Answer 36

An anomaly due to a genetic defect, such as a mutation or chromosomal abnormality.

Question 37

What is a secondary anomaly?

Answer 37

A defect caused by external or environmental influences during development.

Question 38

What are the three types of primary genetic causes of anomalies?

Answer 38

1. Single gene mutations 2.Chromosomal abnormalities 3. Polygenic inheritance

Question 39

Give an example of a single gene defect causing a congenital syndrome.

Answer 39

CHARGE syndrome (CHD7 gene mutation).

Question 40

Give an example of a chromosomal deletion syndrome.

Answer 40

DiGeorge syndrome (22q11.2 deletion).

Question 41

What is a teratogen?

Answer 41

An agent that disrupts normal development, causing congenital anomalies.

Question 42

Name 4 categories of teratogens.

Answer 42

1. Infections (e.g., rubella) 2. Drugs/pollutants (e.g., alcohol, vitamin A) 3. Maternal diseases (e.g., diabetes) 4. Radiation

Question 43

How can maternal diabetes affect fetal development?

Answer 43

Increases the risk of congenital anomalies such as heart and neural tube defects.

Question 44

Which vitamin in excess is a known teratogen?

Answer 44

Vitamin A.

Question 45

What’s the effect of pesticides or alcohol during pregnancy?

Answer 45

Can cause disruption of fetal development leading to anomalies.

Question 46

What happens if a teratogen acts during the pre-embryonic period (0–2 weeks)?

Answer 46

Usually results in lethal damage or complete recovery (all-or-none).

Question 47

Why is the embryonic period (2–8 weeks) critical?

Answer 47

It’s the period of organogenesis and high vulnerability to defects.

Question 48

What kind of defects are common in the fetal period (>9 weeks)?

Answer 48

Mostly functional defects or organ-specific issues.

Question 49

What is a polytopic field defect?

Answer 49

Widespread defects caused by early (2–4 weeks) teratogenic effects.

Question 50

What is a monotopic field defect?

Answer 50

Localized defects due to later (4–8 weeks) teratogenic effects.

Question 51

What’s a “sequence” in congenital development?

Answer 51

An initial defect that leads to a cascade of other problems (e.g., Potter sequence from oligohydramnios).

Question 52

What causes neural tube defects?

Answer 52

Failure of neural tube closure during early development.

Question 53

Which area is most commonly affected in spina bifida?

Answer 53

Lumbosacral region.

Question 54

Name a common complication of spina bifida.

Answer 54

Hydrocephalus.

Question 55

What kind of anomaly is spina bifida?

Answer 55

A malformation due to failure of embryological closure.

Question 56

What kind of anomaly is a cleft palate caused by amniotic bands?

Answer 56

A disruption (started normal, then damaged by external cause).

Question 57

What kind of anomaly is clubfoot from uterine compression?

Answer 57

A deformation (structure was normal, got compressed).

Question 58

How common are congenital anomalies in live births?

Answer 58

Affect about 3% of liveborn infants.

Question 59

What percentage of tertiary care admissions are due to congenital anomalies?

Answer 59

20–30%.

Question 60

Name 3 antenatal screening tools for congenital anomalies.

Answer 60

Triple test Nuchal translucency scan 20-week anomaly scan

Question 61

Why is pre-conception genetic counselling important?

Answer 61

Helps identify and manage risk factors before pregnancy begins.

Question 62

What are some historical misconceptions about congenital anomaly causes?

Answer 62

Beliefs in witchcraft or supernatural causes, still present in some cultures.