Ch. 8 Genetic Testing

Question 1

Define teratogen

Answer 1

Any substance capable of causing abnormal structure in an embryo. The term is derived from the Greek word “terato” which means ‘monster’

Question 2

Causes of congenital malformations include

Answer 2

genetic factors, environmental factors, multifactorial inheritance

Question 3

What are the three categories of teratogens

Answer 3

Physical agents, drugs and chemical agents, maternal factors

Question 4

Physical agents of teratogens include

Answer 4

Radiation, heat (hyperthermia between 4-14 weeks ie, saunas and hot tubs)

Question 5

Signs of fetal alcohol syndrome include

Answer 5

Growth restriction, mental retardation, congenital heart disease, joint anomalies, maxillary hypoplasia

Question 6

what effects could antithyroid drugs have on a fetus

Answer 6

Polydactyly, goiter

Question 7

What effects is aspirin (ASA) known or causing on a fetus

Answer 7

Gastroschisis

Question 8

What is the drug known for causing T-Shaped uterus’ in infants exposed while in utero

Answer 8

DES - Diethylstilbestrol

Question 9

Single gene defect in which one parent is usually affected by the trait and it is evident in each generation

Answer 9

Autosomal dominant

Question 10

Single gene defect in which parents are usually unaffected and the trait may appear to skip a generation

Answer 10

Autosomal recessive

Question 11

A normal, balanced set of chromosomes

Answer 11

Euploid

Question 12

An unbalanced set of chromosomes

Answer 12

Aneuploidy

Question 13

The presence of an extra chromosome

Answer 13

Trisomy

Question 14

The presence of additional set of chromosomes

Answer 14

Triploidy

Question 15

The genetic makeup of an individual

Answer 15

Genotype

Question 16

The expression of the genetic makeup of an individual (both physical and physiologic)

Answer 16

Phenotype

Question 17

During how many weeks is first trimester testing performed

Answer 17

11.5-13.6 weeks

Question 18

What are the two parts to a first trimester genetic screen

Answer 18

Nuchal translucency scan and a maternal blood test of of total beta hCG and PAPP-A

Question 19

What types of defects cannot be detected by CVS

Answer 19

Neural tube defects

Question 20

During what gestational age can an NT be performed, what does the CRL have to measure to be able to evaluate the NT?

Answer 20

11.5-13.6 weeks. the CRL must measure between 45-84 mm.

Question 21

What trisomies does a thickened NT correlate to

Answer 21

Trisomy 21 (downs) and trisomy 18 (edwards)

Question 22

What measurement of the NT is considered abnormal

Answer 22

> 3mm

Question 23

An abnormal NT with a normal karyotype is associated with an increased risk of

Answer 23

Congenital heart disease (CHD)

Question 24

What does NIPT stand for

Answer 24

Noninvasive Prenatal Testing

Question 25

At how many weeks can a pt have NIPT

Answer 25

after 10 weeks

Question 26

Type of genetic sampling that occurs between 9 and 12 weeks, can be performed transcervically or transabdominally with the use of US guidance

Answer 26

Chorionic villus sampling (CVS)

Question 27

What four levels are sampled in a Quad screen aka a multiple marker

Answer 27

Maternal serum alpha-fetoprotein (MSAFP), hCG, unconjugated estriol, and inhibin A

Question 28

The markers on a quad screen increase the detection of which defects

Answer 28

Open neural tube defects (ONTD's).Also trisomy 21 and trisomy 18

Question 29

Where is AFP primarily produced and when is it considered to be the most accurate?

Answer 29

The fetal liver, between 16-18 weeks. (this is why the quad screen is a second trimester screen)

Question 30

List causes of an elevated MSAFP

Answer 30

Incorrect dates (30-40% of cases), multiple gestation, ONTD, abdominal wall defects, placenta chorioangioma, maternal fetal hemorrhage, maternal hepatocellular carcinoma.

Question 31

List reasons of a decreased MSAPF

Answer 31

incorrect dates, chromosome abnormalities, fetal demise

Question 32

How will each marker in a quad screen be affected in a fetus with trisomy 18 aka Edwards syndrome

Answer 32

MSAFP- Decreased hCG- decreased Unconjugated estriol- decreased

Question 33

How will each marker in a quad screen be affected in a fetus with trisomy 21 aka Down Syndrome

Answer 33

MSAFP- decreased hCG- increased unconjugated estriol- decreased Inhibin A- increased

Question 34

During what gestation is genetic amniocentesis usually performed

Answer 34

around 16 weeks

Question 35

What is used in a multiple gestation during genetic amniocentesis in order to ensure the same sac is not being tapped more than once

Answer 35

A dye known as indigo carmine