Lecture 8: Birth Defects

Question 1

What is the most common birth defect?

Answer 1

Congenital heart defects

Question 2

What are the known causes of birth defects?

Answer 2

twinning
genetics (xs abnormalities, gene mutations)
environmental factors
gene + environment (multifactorial inheritance)

Question 3

What kind of birth defect is Turner syndrome an example of?

Answer 3

Monosomy (X)

Question 4

What is the inheritance pattern of Axenfeld-Rieger syndrome?

Answer 4

autosomal dominant

Question 5

As seen in Axenfeld-Rieger syndrome, mutations in ______ can alter the development of multiple systems.

Answer 5

single genes

Question 6

What are symptoms of Axenfeld-Rieger syndrome?

Answer 6

ocular defects
dental abnormalities
widely spaced eyes
prominent forehead
extra folds around belly button

Question 7

What genes are known to be mutated in Axenfeld-Rieger syndrome? what role do they have?

Answer 7

PITX2
FOXC1
embryonic development

Question 8

What is the difference between monogenic traits and complex traits?

Answer 8

complex traits have many contributing genes and non-genetic influences

Question 9

What do genetic factors called modifier genes contribute to?

Answer 9

complex traits

Question 10

What are three genetic causes of holoprosencephaly?

Answer 10

xs abnormality (#, structure)
env condition (maternal diabetes)
single gene mutations

Question 11

In what diease are SHH, PTCH1, GLI2, and DISP1 involved?

Answer 11

holoprosencephaly

Question 12

What is an example of an infectious agent which causes birth defects?

Answer 12

Rubella –> Congenital Rubella Syndrome

Question 13

What structure can have a birth defect due to hyperthermia (fever)?

Answer 13

neural tube defects

Question 14

Coxackie virus, Cytomegalovirus, herpes simplex, parvovirus, rubella (German measles), Toxoplasma gondii (toxoplasmosis), Treponema pallidum (syphilis) are all _______ which can cause _______

Answer 14

infectious agents

birth defects

Question 15

What birth defect did thalidomide cause?

Answer 15

phocomelia (limb defects)

Question 16

What are two prevalent hypotheses for how thalidomide caused birth defects?

Answer 16

1. inducing oxidative stress

2. disrupting angiogenesis

Question 17

What are the names for the study of birth defects, and for agents which cause birth defects?

Answer 17

teratology

teratrogens

Question 18

On what factors does susceptibility of teratogens depend?

Answer 18

development stage at time of exposure
dosage and duration of exposure
genotype (embryo or mom) - gene-env interations

Question 19

What is the most sensitive period for inducing birth defects?

Answer 19

weeks 3-8 during embryogenesis

Question 20

People with _____ can have trouble learning and remembering, understanding and following directions, controlling emotions, communicating and socializing, and with daily skills

Answer 20

Fetal Alcohol Syndrome (FAS)

Fetal Alcohol Spectrum Disorders (FASD)

Question 21

Microcephaly, indistinct philtrum, narrow upper lip, low nose bridge, and flat midface all characterize what?

Answer 21

Fetal Alcohol Syndrome

Question 22

With what cell processes is alcohol thought to interfere?

Answer 22

migration
adhesion
proliferation
survival
signaling
gene expression

Question 23

What type of antidepressants have been associated with a low risk of birth defects?

Answer 23

SSRIs (selective seratonin reuptake inhibitors)

Question 24

What are the majority of congenital heart defects due to?

Answer 24

Multifactorial - genes + env

Question 25

What do congenital heart defects change?

Answer 25

route of blood flow

Question 26

What results from a septal defect?

Answer 26

A hole in the heart

Question 27

What are the two causes of septal defects?

Answer 27

Excessive cell death

Inadequate septum development

Question 28

What is it called when the heart is positioned on the right side of the thorax instead of the left?

Answer 28

Dextrocardia

Question 29

What is double outlet right ventricle?

Answer 29

Aorta comes from right ventricle (instead of left)