Genetic screening

Question 1

genetic screening is a

Answer 1

population based approach for identifying individuals with increased susceptibility to or risk for a genetic disease in themselves and their offspring.

Question 2

newborn screening purpose

Answer 2

screening of all babies just after birth.
it identifies genetic diseases that can be treated early in life.
It is performed by state public health deparments and commercial laboratories.

Question 3

general criteria for newborn screening

Answer 3

treatment is available
early initiation of treatment before symptoms become manifest, reduces or prevents severe illness
routine observation of newborn will not reveal the disorder.
condition is frequent and severe enough to justify screening.
follow up and counseling are available.

Question 4

prototype for newborn screening is

Answer 4

phenylketouria (PKU) screening

Question 5

today newborn screening is done by

Answer 5

tandem mass spectrometry (MSMS)

Question 6

federal government recommends that every newborn screen program in the US include a uniform screening panel of

Answer 6

31 primary and 26 secondary conditions.

this panel is the recommended uniform screening panel.

Question 7

carrier screening is used to

Answer 7

identify individuals who are carriers for recessive disease in specific ethnic populations.

It is also used to identify couples in which both individuals are carriers for the same genetic disease.

Question 8

prototype for carrier screening: tay sachs disease

Answer 8

first done with enzyme assay

now performed with DNA and/or enzyme

Question 9

tay sachs disease symptoms

Answer 9

progressive mental and motor degeneration
macular degeneration
paralysis
uncontrollable seizures

Question 10

tay sachs disease carrier frequency

Answer 10

ashkenazi Jewish 1:25

french Canadian 1:25

Question 11

maternal serum screening is done on woman ages

Answer 11

35 and older

Question 12

maternal serum screens for

Answer 12

alpha fetoprotein (detects neural tube defects and chromosomal abnormalities)

quad screening (four sserum markers increase detection rate of NTD and chromsome abnormalities)

Question 13

alpha fetoprotein (AFP)

Answer 13

a fetal protein which is produced initially by the yolk sac and then the fetal liver.
it is elevated in fetuses with neural tube defects
it is decreased in fetuses with chromosome defects.

Question 14

alpha fetoprotein (AFP) is elevated in maternal serum because AFP

Answer 14

diffuses across the placenta.

Question 15

accuracy of screening for chromosome abnormalities is improved by measuring maternal serum levels of

Answer 15

unconjugated estriol
human chorionic gonadotropin
inhibin

Question 16

second trimester maternal serum screening

Answer 16

the test result is very dependent on accurate determination of the gestational age of the fetus. If the gestational age of the fetus has not been accurately determined, the results may be either falsely high or low.

Question 17

triple screen for down syndrome

Answer 17

AFP, estradiol, hCG
69% all ages
49% <35, 88% >35

Question 18

quad screen for down syndrome

Answer 18

AFP, estriol, hCG, inhibin
77% all ages
69% <35, 91% >35

Question 19

however, if a patient tested for triple and quad screen has an ultrasound, then the detection of fetuses with down syndrome increases from

Answer 19

69% to over 95%

Question 20

maternal serum screening: of the positive test reslts, a significant percentage of these babies

Answer 20

will not have any anomalies.

There may be other benign reasons for the elevated or low levels of the hormones, specifically gestational age or multiple pregnancies.

Question 21

advanced maternal age

Answer 21

women >35 years have a higher risk of having a down syndrome child or other chromosomal abnormalities.

Question 22

recommended that women >35 years have

Answer 22

CVS or amniocentesis:
prenatal chromosome screening
measurement of fetal alpha-fetoprotein

Question 23

70% of all kinder mit major autosomal trisomies are born to women younger than 35 years who

Answer 23

usually do not have CVS or amnios.

therefore, maternal serum protein markers are important in identifying children with autosomal trisomies of younger mothers.

Question 24

considerations for carrier screening in some religious communities

Answer 24

prenatal diagnosis not feasible, abortion not permitted
AID or birth control not options
marriages aranged
compatibility testing (genetic screening prior to matches)