Genetic Testing

Question 1

Quad Screen Components

timing?

Answer 1

-HCG
-UE3
-AFP
-INHIBIN A

timing = 15-22w

Question 2

Screening with highest T21 sensitivity?

Answer 2

NIPT / cfDNA

99% sensitivity; 0.05% false pos

Question 3

Combined Screen Components

Answer 3

sono (NT) +
blood (bhcg, PAPP-A)

timing = 10-13w

Question 4

How does AFP detect neural tube defects?

Answer 4

produced by fetal yolk sac + developing liver -> leaks into bloodstream in higher quantities when NTD is present

Question 5

NT sensitivity for T21

Answer 5

~64-70%

Question 6

Minimum fetal fraction for cfDNA to report adequate result?

Answer 6

4%

Question 7

Min. NT threshhold to offer immediate dx testing?

Why?

Outcomes %

Answer 7

3mm

95ile of NT

Normal 70-90%
Miscarriage 2-10%

Question 8

Increased NT assoc w/ which aneuploidies?

Answer 8

T13 (Patau)
T18 (Edward)
T21 (Down)
Monosomy X
Triploidy

Question 9

Who to offer CF carrier screening to?

How screened?

Answer 9

all women

CFTR gene mutation (full DNA sequencing for high-risk)

Question 10

CF inheritance

Answer 10

AR

Question 11

What to do if pt requests carrier screening

Answer 11

if reasonable, inexpensive, can do if after r/b/a convo

Question 12

Who to offer SMA screen

Answer 12

all pts

Question 13

Who to offer hemoglobin electrophoresis to

Answer 13

-all patients in first prenatal visit (if no previous screening
-if suspected hemoglobinopathy based on ethnicity (SE Asian, African, Mediterranean/Middle Eastern, W Indian)

Question 14

Who to offer Fragile X Screen to?

Answer 14

1. Family hx Fragile X
2. personal hx ID that seems like Fragile X
3. ovarian insufficiency or elev FSH <40yo

Question 15

Fragile X triploid repeat

Answer 15

CGG

Question 16

Fragile X premutation repeat #

Answer 16

55-200

Question 17

Fragile X mutation repeat #

Answer 17

> 200

Question 18

GA at which NT is most sensitive

Answer 18

13w GA

Question 19

Etiol Angelman S/D

Answer 19

maternal imprinting d/o Ch 15

Question 20

Etiol Prader-Willi

Answer 20

paternal imprinting d/o Ch 15

Question 21

Etiol Beckwith-Wiedemann S/d

Answer 21

Paternal imprinting d/o Chr 11

Question 22

Etiol Russel-Silver S/D

Answer 22

maternal imprinting d/o Ch 7

Question 23

Etiol Kallman S/D

Answer 23

gene mutation

Question 24

Kallman s/d Sx

Answer 24

anosmia
hypothalamic hypogonadism (absent or delayed puberty)

Question 25

Angelman S/D sx

Answer 25

ID, develop delays balance and movement d/o

Question 26

Prader-Willi S/D Sx

Answer 26

short stature hypotonia obese small hands / feet ID

Question 27

Which patients do you offer dx testing to?

Answer 27

All, at first visit (educated,

Question 28

Turner S/D findings

Answer 28

1. coarctation of aorta 2. shield chest 3. webbed 4. short stature 5. streak ovaries

Question 29

Contingent Screening Strategy

Answer 29

1. 1T screen 2. Stratify into low, intermediate, high risk **LOW: **no additional test **INTERMED**: 2T screen **HIGH**: offer dx test or cfDNA

Question 30

Sequential Screening Strategy

Answer 30

1. 1T Screen 2. Stratify into low vs high risk **Low**: 2T screen **High**: dx test vs cfDNA

Question 31

Integrated Screening Strategy

Answer 31

1. 1T screen 2. 2T screen 3. GET ALL RESULTS TOGETHER | con: later dx

Question 32

Factor V Leiden carrier frequency: in white pts

Answer 32

5%

Question 33

Factor V Leiden mutation MoA

Answer 33

mutation prevents FVLeiden inactivation by protein C -> prone to clots

Question 34

AFP level unit of measurement

Answer 34

multiples of median (MoM) | based on gesetational age

Question 35

AFP detection rates: -anencephaly -open NT defects

Answer 35

anencephaly: 95% open NT defect: 65-80% | when MSAFP >2.5MoM