Chapter 8 Exam 2

Question 1

What are genetic testing approaches?

Answer 1

Tests that can be done on individuals, individual families or large groups such as member of an ethnic group

Question 2

What are preimplantation genetic diagnosis?

Answer 2

used with IVF (in vitro fertilization), is able to identify embryos with specific genotypes

Question 3

How is an ultrasound used to detect abnormalities?

Answer 3

is noninvasive, uses reflected sound waves that are converted to an image. Chromosomes cannot be seen. May identify potential chromosomal abnormalities by physical features and phenotypes associated with them

Question 4

What is amniocentisis and when is it normally used?

Answer 4

can diagnose more than 1000 disorders, cells and fluids are taken and analyzed for chromosomal an dbiochemical disorders. There is a high risk of infection and loss of child. Normally only used when:
o Maternal age >35
o History of chromosomal disorder in other children
o Parent with known chromosomal abnormality
o Mother is a carrier of an X-linked disorder
o History of miscarriages

Question 5

What is chorionic villus sampling?

Answer 5

done for similar reasons as amniocentesis but is performed earlier than amniocentesis (6-10 weeks vs. 16 weeks). Karyotypes are available within a few hours or days; there is an increased risk of spontaneous abortion (0.5-2%). DNA testing for individual conditions could be performed as well as biochemical testing

Question 6

How are fetal cells from maternal circulation used?

Answer 6

Types include placental cells, white blood cells, and immature red blood cells with nuclei. They enter the bloodstream at 6 and 12 weeks, fetal cells are only 1/100000. Techniques have been developed to isolate these cells and fetal DNA from the mother’s blood

Question 7

Details on PKU testing

Answer 7

all states test for PKU in babies using blood samples from the babies. This is a biochemical test not a DNA test.

Question 8

What are some of the most common genetic disorders?

Answer 8

o	Cystic fibrosis
o	Congenital adrenal hyperplasia
o	Duchenne muscular dystrophy
o	Hemophilia A
o	Alpha and beta thalassemia
o	Huntington disease
o	Polycystic kidney disease
o	Sickle cell anemia
o	Tay-Sachs disease

Question 9

Newborn screening in the US and how it began:

Answer 9

States are required by federal law to screen for 30-50 conditions. The focus is on easily identified and treatable conditions and it began in the 60’s with testing for PKU

Question 10

How are Utah newborn screening tests done and what do they test for?

Answer 10

Utah collects two newborn screening specimens which test for 37 disorders. The first is done before the child leaes the hospital and the next is done within the first month of life. Includes tests for
o	PKU
o	Sickle cell hemoglobin and other hemoglobin conditions
o	Galactosemia
o	Tyrosinemia I and II
o	Defects in fatty acid metabolism
o	Defets in amino acid metabolism
o	Congenital adrenal hyperplastia
o	Cystic fibrosis
o	SCID

Question 11

How can PKU be treated?

Answer 11

diet that is low in phenylalanine

Question 12

How can sickle cell anemia be treated?

Answer 12

bone marrow transplants and blood transfusions

Question 13

How can hemophilia be treated?

Answer 13

with recombinant DNA

Question 14

How can cystic fibrosis be treated?

Answer 14

inhalers, antibiotics

Question 15

How can polycystic kidney disease be treated?

Answer 15

kidney transplant, dialysis

Question 16

How are Utah’s cystic fibrosis screening tests done?

Answer 16

done in an IRT test, followed by a recall IRT, than a DNA genotype test [IRT/IRT/DNA]. IRT is an antibody test for high blood levels of trypsinogen. DNA testing is done for the 31 mutations known to cause Cystic Fibrosis

Question 17

What is galactosemia?

Answer 17

occurring in newborns, it is the inability to completely digest lactose. Is tested for in Utah’s newborn testing. (is different from lactose intolerance. The Galactosemia allele is completely nonfunctioning

Question 18

What is lactose intolerance?

Answer 18

an adult condition, related to digestion of lactose

Question 19

Genetic screens vs. Genetic tests:

Answer 19

genetic screens look at populations or groups, while genetic tests look at individuals

Question 20

What are some adult screening programs?

Answer 20

carrier and presymptomatic testing are available (or soon will be) for the following conditions: Huntington disease, genetic predisposition to breast cancer, ALS, and polycystic kidney disease (PCKD)

Question 21

What is Tay-Sachs disease?

Answer 21

a fatal autosomal recessive trait that affects 1/360000. It’s a disorder of lysosomes, leading to mental retardation, blindness and death by age 3 or 4. Is 100 times more likely to occur in Jews of Eastern European ancestory. In 1970s a carrier detection screening program was implemented that eventually reduced the number of affected babies by 90% as parents made different reproductive choices

Question 22

Sickle cell anemia testing of African-Americans:

Answer 22

in 1972, states received funds to identify carriers of sickle cell anemia. Those of African descent were forced to undergo testing before they attended school, obtained a marriage license, play professional football or apply to the Air Force Academy. Most of these have stopped because they were discriminatory

Question 23

What is the future of DNA based genetic testing?

Answer 23

if DNA sequencing becomes less expensive, then one could have most of the relevant regions of the genomes sequenced to detect potentially important genetic conditions

Question 24

How is biochemistry based genetic testing helpful?

Answer 24

the analysis of biomolecules in serum or tissue- to predict risk of disease, identifies carriers, and establishes prenatal or clinical diagnoses or prognoses.