Week 7- Prenatal Diagnosis and Treatment

Question 1

What are 3 main reasons prenatal testing is done?

Answer 1

Family history or carrier testing
Advanced maternal age
Routine prenatal care

Question 2

What is the goal of prenantal testing?

Answer 2

Inform couples about the risk of a birth defect or genetic disorder so they can make informed choices

Question 3

What are some non-invasive tests?

Answer 3

Serum (maternal alpha fetoprotein)
Ultrasonography
Isolation of fetal cells from maternal circulation

Question 4

What are 4 invasive tests for prenatal diagnosis and screening?

Answer 4

Amnicentesis
CVS (chorionic villus sample)
Cordocentesis)
Preimplantation genetic diagnosis

Question 5

What is the removal of a needle into the amniotic sac to remove a sample of fluid?

Answer 5

Amniocentesis

Question 6

When is an amniocenteisis normally performed?

Answer 6

15-16 weeks

Question 7

What does an amniocentesis test?

Answer 7

Fetal chromosomes

Concentration of alpha-fetoprotein (AFP) in amniotic fluid

Question 8

What does elevated AFP indicate?

Answer 8

Neural tube defect

Question 9

What does decreased AFP indicate?

Answer 9

Down’s Syndrome

Question 10

Where is AFP? Where is it excreted?

Answer 10

AFP is produced in the liver

Excreted by the kidneys

Question 11

What is MSAFP?

Answer 11

Maternal serum AFP, non-invasive method

Question 12

What is AFAFP?

Answer 12

Amniotic fluid, AFP, invasive

Question 13

What test takes a biopsy of tissue from villous area of the chorion?

Answer 13

Chorionic Villus Sample

Question 14

When is Chorionic Villus Sampling performed?

Answer 14

10-12 weeks of gestation

Question 15

Can you assay AFP at the stage in which chorionic villus sampling is done?

Answer 15

No

Question 16

When is there a high rate of mosaicism?

Answer 16

Chorionic Villus Sampling

Question 17

What do you need for a definitive diagnosis of a NTD?

Answer 17

Ultrasonography

Question 18

periconceptional supplementation with folic acid reduces risk of _____ and ______ ?

Answer 18

NTD and orofacial clefting

Question 19

In many trisomic pregnancies ____ is depressed.

Answer 19

MSAFP

Question 20

What tests are done in the first trimester?

Answer 20

PAPP-A
hCG
Nuchal tranlucency

Question 21

What is PAPP-A?

Answer 21

Pregnancy associated plasma protein A

Question 22

Lower values of PAPP-A indicate what?

Answer 22

Aneuploidy

Question 23

What is looking at the thickness of echo free space b/w skin and soft tissue overlying the dorsal aspect of the cervical spine?

Answer 23

Nuchal translucency

Question 24

Abnormal excess of fluid in nuchal translucency indicates what?

Answer 24

Trisomies

45, X fetus

Question 25

In second trimester screening, what are the three tests in the triple screen? What is the 4th if a quad screen is performed?

Answer 25

Triple- MSAFP, free Beta-hCG, unconjugated estriol | Quad- add on Inhibin A

Question 26

When is the only instance where Inhibin A levels are increased?

Answer 26

Trisomy 21

Question 27

Does a negative screen mean that a trisomy or NTD isn't present?

Answer 27

No- but risk is greatly reduced

Question 28

What is a high-resolution real time scan that is important for: assessment of fetal age fetal viability detection of morphological abnormalities

Answer 28

Ultrasonography

Question 29

In order for a single gene disorder to be detected on ultrasonography what must it have?

Answer 29

A well defined phenotypic abnormality

Question 30

What is an autosomal dominant disorder with congenital heart defects and hand anomalies?

Answer 30

Holt-Oram Syndrome

Question 31

When is ultrasonography for fetal sex performed?

Answer 31

At 15 weeks of gestation (many times in conjunction with diagnosis of X-linked disorder)

Question 32

How long does culture and analysis take for cytogenetics?

Answer 32

7-10 days

Question 33

What screen is common for aneuplodies and can happen soon after amniocentesis or CVS. takes 1-2 days for rapid aneuploidy testing.

Answer 33

FISH (florescent in situi hybridization)

Question 34

In the use of cytogenetics from a sample obtained from CVS what is one of the drawbacks?

Answer 34

Banding resolution is lowered | Aneuploidies can be found, but not much after that

Question 35

What are the 3 more common abnormal karyotypes

Answer 35

Trisomies Turner Syndrome Unbalanced structural abnormalities

Question 36

What is the presence of two or more cell lines in an individual or tissue sample?

Answer 36

Mosaicism

Question 37

What is true mosaicism?

Answer 37

Multiple colonies from several different primary cultures

Question 38

What is pseudomosaicism

Answer 38

Only seen in a single cell- usually disregarded

Question 39

What might be the cause of mosaicism when XX and XY cells present?

Answer 39

Maternal cell contamination (more common in CVS)

Question 40

What is confined placental mosaicism?

Answer 40

When mosaicism may be present in placenta but absent in fetus.

Question 41

What is when a fertilized ovum containing three copies of a chromosome loses one of these chromosomes to form a normal, diploid chromosome complement.

Answer 41

Trisomy rescue

Question 42

What are 2 main problem with prenatal chromosome analysis.

Answer 42

Mosaicism | Culture failure

Question 43

How many disorders can be diagnosed in cultured fetal cells?

Answer 43

Over 100, but most are autosomal recessive

Question 44

What is an advantage to biochemical testing over DNA?

Answer 44

Biochemical testing can detect any abnormality that affects the protein but DNA analysis is only accurate for detection of mutation being tested

Question 45

In what disorder have prenatal bone marrow transplants been successful?

Answer 45

SCID

Question 46

Prenatal treatment is most successful in what type of disorders?

Answer 46

Metabolic disordes