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OB GYN REGISTRY > Ch. 8 Genetic Testing > Flashcards

Ch. 8 Genetic Testing Flashcards

1
Q

Define teratogen

A

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

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2
Q

Causes of congenital malformations include

A

genetic factors, environmental factors, multifactorial inheritance

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3
Q

What are the three categories of teratogens

A

Physical agents, drugs and chemical agents, maternal factors

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4
Q

Physical agents of teratogens include

A

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

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5
Q

Signs of fetal alcohol syndrome include

A

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

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6
Q

what effects could antithyroid drugs have on a fetus

A

Polydactyly, goiter

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7
Q

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

A

Gastroschisis

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8
Q

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

A

DES - Diethylstilbestrol

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9
Q

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

A

Autosomal dominant

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10
Q

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

A

Autosomal recessive

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11
Q

A normal, balanced set of chromosomes

A

Euploid

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12
Q

An unbalanced set of chromosomes

A

Aneuploidy

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13
Q

The presence of an extra chromosome

A

Trisomy

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14
Q

The presence of additional set of chromosomes

A

Triploidy

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15
Q

The genetic makeup of an individual

A

Genotype

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16
Q

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

A

Phenotype

17
Q

During how many weeks is first trimester testing performed

A

11.5-13.6 weeks

18
Q

What are the two parts to a first trimester genetic screen

A

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

19
Q

What types of defects cannot be detected by CVS

A

Neural tube defects

20
Q

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

A

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

21
Q

What trisomies does a thickened NT correlate to

A

Trisomy 21 (downs) and trisomy 18 (edwards)

22
Q

What measurement of the NT is considered abnormal

A

> 3mm

23
Q

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

A

Congenital heart disease (CHD)

24
Q

What does NIPT stand for

A

Noninvasive Prenatal Testing

25
Q

At how many weeks can a pt have NIPT

A

after 10 weeks

26
Q

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

A

Chorionic villus sampling (CVS)

27
Q

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

A

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

28
Q

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

A

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

29
Q

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

A

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

30
Q

List causes of an elevated MSAFP

A

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

31
Q

List reasons of a decreased MSAPF

A

incorrect dates, chromosome abnormalities, fetal demise

32
Q

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

A

MSAFP- Decreased
hCG- decreased
Unconjugated estriol- decreased

33
Q

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

A

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

34
Q

During what gestation is genetic amniocentesis usually performed

A

around 16 weeks

35
Q

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

A

A dye known as indigo carmine

OB GYN REGISTRY (19 decks)

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