Embryology & Organogenesis

Question 1

Deformation

Answer 1

compression or biochemical distortion of an already normally formed body part which usually occurs after 10-12 weeks gestation. Examples include clubfoot,
joint contractures, and plagiocephaly (a flat spot on a baby’s head).

Question 2

Disruption

Answer 2

Compression or biomechanical distortion of an already formed (or to be formed) normal body part to such an extreme that the resulting defect looks like a malformation. Examples include amniotic bands (occurs when the lining of the amniotic sac is damaged during pregnancy. This creates string-like strands of tissue t in which the fetus gets tangled. These strands (called amniotic bands) may wrap around different parts of the developing body), web neck due to cystic hygroma.

Question 3

Malformation

Answer 3

congenital anomaly resulting from improper organogenesis. Examples
include cleft lip, esophageal atresia (Esophageal atresia is a birth defect of the swallowing tube (esophagus) that connects the mouth to the stomach. In a baby with esophageal atresia, the esophagus has two separate sections—the upper and lower esophagus—that do not connect), anencephaly (underdeveloped brain and an incomplete skull).

Question 4

Sequence

Answer 4

A situation where a single event (usually undefined) leads to a single anomaly (or situation) that has a cascading effect of local and/or distant deformations and/or
disruptions. Examples include Potter sequence, and Pierre Robin.

Pierre Robin is a rare congenital birth defect characterized by an underdeveloped jaw, backward displacement of the tongue and upper airway obstruction.
Cleft palate is also commonly present in children with Pierre Robin sequence.

Question 5

Gen pop risk for birth defects is…

Answer 5

The general population risk for birth defects is 3-5%

Question 6

neural tube defect incidence

Answer 6

NTDs: Incidence of 1-2/1,000

Question 7

Meckle Gruber

Answer 7

NTD = occipital encephalocele, cystic renal disease, polydactyly, AR inheritance

Question 8

Incidences of anencephaly and spina bifida chart

Answer 8

(2 sibs born w/ SB or anencephaly will have highest recurrence risk for a 3rd) (Risk increases w/ more affected relatives)

Question 9

What is the recommendation for women for the prevention of neural tube defects in pregnancy for women who have previously had a pregnancy affected by NTDs?

Answer 9

After having a pregnancy affected with an NTD, the recommendation is that women who are considering pregnancy take 4mg of folic acid one month before pregnancy and continue through the third month of pregnancy.

Question 10

What is the recommendation for women for the prevention of neural tube defects in pregnancy?

Answer 10

.4mg (400umg) of folic acid for prevention

Question 11

Folic acid supplementation reduces the risk of NTDs by what percentage?

Answer 11

70%

Question 12

What is the most common congenital viral infection?

Answer 12

CMV
Cytomegalo Virus

Question 13

Is CMV apparent in most cases in the newborn?

Answer 13

No, it is not clinically apparent in 90% of cases, it may cause a mild febrile illness and other nonspecific symptoms including rhinitis, pharyngitis, myalgia, arthralgia, headache, fatigue

Question 14

What is serosurveillance?

Answer 14

the testing of blood samples for the presence of antibodies against a particular disease, due to past infection or vaccination, in the general population

Question 15

What is the seroprevalence globally in females of childbearing age for CMV?

Answer 15

86%

Question 16

What factors increase the risk for maternal-fetal transmission of CMV?

Answer 16

Patients who seroconvert during pregnancy (primary infection) are at the highest risk for maternal-fetal transmission and the frequency of vertical transmission appears to increase with advancing gestational age. The percentage risk increases from the preconception period up to 12 weeks before the last menstrual period (5.5%) through the third trimester (66.2%).

Question 17

What are some findings in symptomatic newborns for CMV?

Answer 17

small for gestational age
microcephaly
ventriculomegaly
chorioretinitis
jaundice
hepatosplenomegaly
thrombocytopenia
petechiae

Question 18

Newborns infected with CMV are at risk for adverse outcomes including death and serious long-term neurologic morbidity, including progressive sensorineural hearing loss in early life. What factor increases a newborn’s risk for these adverse outcomes?

Answer 18

Whether they are symptomatic or asymptomatic. Newborns who are symptomatic have a 5% risk of death compared to 0% for asymptomatic. Symptomatic newborns also have a 50-60% risk of serious long-term neurologic morbidity compared to 15-25% for asymptomatic newborns.

Question 19

What is toxoplasmosis?

Answer 19

Toxo is a parasitic infection found in cat feces and undercooked beef.

Question 20

What is the most common ultrasound finding in cases of toxoplasmosis?

Answer 20

Intracranial hyperechogenic foci (calcifications/densities) (intracranial calcifications)

Question 21

What is a factor that increases the frequency of fetal infection for toxoplasmosis?

Answer 21

advancing gestational age at the time of maternal seroconversion. The risk at 13 weeks is 15% and rises to 71% at 36 weeks.

Question 22

What is hydrops fetalis?

Answer 22

Hydrops fetalis is severe swelling (edema) in an unborn baby or a newborn baby. It is a life-threatening problem. Hydrops develops when too much fluid leaves the baby’s bloodstream and goes into the tissues. Treatment of hydrops depends on the cause. About 50% of unborn babies with hydrops don’t survive.

Question 23

What is another name for Parvovirus B19 infection?

Answer 23

Fifth disease

Question 24

When is Parvovirus B19 infection common?

Answer 24

during childhood

Question 25

What are the concerns related to Parvovirus B19?

Answer 25

Infection during pregnancy may result in fetal loss or hydrops fetalis.
Children who do not develop hydrops fetalis don’t appear to have any long-term developmental sequelae.
sequelae = a condition which is the consequence of a previous disease or injury

Question 26

How can maternal infections for parvovirus B19 infection be completed and what do the results mean?

Answer 26

Testing is done via maternal serology by testing for IgG and IgM antibodies in maternal serum.
IgM = recent exposure
IgG = exposure in the past and is immune
IgM & IgG = exposure in the last ~13 months

Question 27

What is anticonvulsant embryopathy?

Answer 27

Fetal anticonvulsant syndrome is a cluster of a variety of congenital malformations in infants exposed to antiseizure drugs in utero.

Question 28

What are the major congenital malformations related to anticonvulsant embryopathy?

Answer 28

cardiac defects
neural tube defects
oro-facial clefts
hypospadias (a birth defect in boys in which the opening of the urethra is not located at the tip of the penis)

Question 29

What are the minor malformations related to anticonvulsant embryopathy?

Answer 29

hypertelorism (an increased distance between two body parts)
flat nasal ridge
long philtrum (the vertical groove between the base of the nose and the border of the upper lip)
low-set ears
microcephaly (head is much smaller than expected)
short neck
digital anomalies
cognitive and behavioral disturbances
intrauterine growth restriction

Question 30

What medications pose a risk for anticonvulsant embryopathy?

Answer 30

trimethadione
hydantoin
barbiturates
carbamazepine
valproic acid

(mnemonic: tri hy baclava)
Hi, try my baclava

Question 31

Which route of drug administration poses the lowest risk of teratogenicity?

Answer 31

topical application

Question 32

What levels of radiation exposure is considered teratogenic?

Answer 32

5 rads and above
A dental x-ray exposes a person to about as much radiation as one gets flying across the continental US in a plane. A diagnostic x-ray has 0.1 rads

Question 33

Are amniotic bands associated with genetic syndromes?

Answer 33

No.
They are an important cause of congenital anomalies though.

Question 34

What is postaxial polydactyly? Which population is it common in? What is the inheritance pattern? And what is expressivity for this trait?

Answer 34

an extra digit or a part of a digit on the ulnar (pinkie side) or fibular (outside) side of the hand or foot
African American
variable expressivity

Question 35

What relationship poses the highest risk for recurrence of isolated cleft palate?

Answer 35

Two affected siblings

Question 36

What relationships pose the highest risk for recurrent of cleft lip and palate?

Answer 36

Two affected siblings or a sibling and affected parent

Question 37

The recurrence risk to future siblings of a child with bilateral cleft lip and palate, unilateral cleft lip and palate, or unilateral cleft lip alone range in what percentage?

Answer 37

2.5 - 5.7%
Risk is highest for bilateral cleft lip and palate.
Risk if lowest for unilateral cleft lip alone.

Question 38

When more than two affected first-degree relatives have congenital heart disease, what is the overall risk for a person?

Answer 38

about 50%
this is the highest-risk relationship status to have, the next highest is two affected siblings or sib and a parent

Question 39

What is the approximate risk for siblings of isolated cases of non-syndromic congenital heart disease?

Answer 39

1 - 5%
Isomerism sequence is the only one with a 5% risk, all others are lower. They are all at least 1% though.

Question 40

Which relative of a person with infantile pyloric stenosis is at greatest risk of developing this condition?

Answer 40

Sons of a mother with infantile pyloric stenosis. They have an 18.9% risk which is a 38x increased risk.
Affected females’ relatives have a higher risk of inheriting it in general
Pyloric stenosis is the narrowing of the opening from the stomach into the small intestine.
Threshold theory:
male needs to have 4 different strikes to get it, females need 12 strikes. This is an example of threshold theory.

Question 41

Which group of relatives have the highest genetic risk of Hirschsprung disease?

Answer 41

Offspring of those with long aganglionic segment of Hirschsprung disease which is a birth defect - missing nerve cells in large intestine - can’t move stool and becomes blocked.
The brothers of males and females with Hirschsprung disease are at the next highest risk at about 16 and18%.

Question 42

What is the most common adverse outcome from a prenatal CMV infection?

Answer 42

progressive sensorineural hearing loss

Question 43

What congenital malformations can be caused by anticonvulsant embryopathy?

Answer 43

• major congenital malformations such as cardiac and neural tube defects, oro-facial clefts, and hypospadias
• minor malformations such as hypertelorism, flat nasal ridge, long philtrum, low-set ears, microcephaly, short neck) and digital anomalies (hypoplasia of the distal phalanges or nails), as well as cognitive and behavioral disturbances and intrauterine growth retardation.