Chapter 6

Question 1

pedigree

Answer 1

Pictorial representation of a family history outlining the inheritance of one or more traits or diseases.

Question 2

proband

Answer 2

A person having a trait or disease for whom a pedigree is constructed.

Question 3

consanguinity

Answer 3

Mating between related individuals.

Question 4

dizygotic twins

Answer 4

Nonidentical twins that arise when two different eggs are fertilized by two different sperm; also called fraternal twins.

Question 5

monozygotic twins

Answer 5

Identical twins that arise when a single egg fertilized by a single sperm splits into two separate embryos.

Question 6

concordance

Answer 6

Percentage of twin pairs in which both twins have a particular trait.

Question 7

genetic counseling

Answer 7

Educational process that attempts to help patients and family members deal with all aspects of a genetic condition.

Question 8

ultrasonography

Answer 8

Procedure for visualizing the fetus. High-frequency sound is beamed into the uterus. Sound waves that encounter dense tissue bounce back and are transformed into a picture of the fetus.

Question 9

amniocentesis

Answer 9

Procedure used for prenatal genetic testing to obtain a sample of amniotic fluid from a pregnant woman. A long sterile needle is inserted through the abdominal wall into the amniotic sac to obtain the fluid.

Question 10

chorionic villus sampling

Answer 10

Procedure used for prenatal genetic testing in which a small piece of the chorion (the outer layer of the placenta) is removed from a pregnant woman. A catheter is inserted through the vagina and cervix into the uterus. Suction is then applied to remove the sample.

Question 11

karyotype

Answer 11

Picture of an individual organism’s complete set of metaphase chromosomes.

Question 12

maternal blood screening test

Answer 12

Tests for genetic conditions in a fetus by analyzing the blood of the mother. For example, the level of α-fetoprotein in maternal blood provides information about the probability that a fetus has a neural-tube defect.

Question 13

noninvasive prenatal genetic diagnosis

Answer 13

A genetic test performed on an unborn fetus without taking a tissue sample from the fetus. Usually performed by testing fetal DNA that occurs within the maternal blood.

Question 14

fetal cell sorting

Answer 14

Separation of fetal cells from maternal blood. Genetic testing on the fetal cells can provide information about genetic diseases and disorders in the fetus.

Question 15

preimplantation genetic diagnosis

Answer 15

Genetic testing on an embryo produced by in vitro fertilization before implantation of the embryo in the uterus.

Question 16

newborn screening

Answer 16

Tests newborn infants for certain genetic disorders.

Question 17

pre symptomatic genetic testing

Answer 17

Tests people to determine whether they have inherited a disease-causing gene before the symptoms of the disease have appeared.

Question 18

heterozygote screening

Answer 18

Tests members of a population to identify heterozygous carriers of a disease-causing allele who are healthy but have the potential to produce children who have the disease.

Question 19

direct-to-consumer genetic test

Answer 19

Test for a genetic condition; the test can be purchased directly by a consumer, without the involvement of a physician or other health care provider.

Question 20

Genetic Information Nondiscrimination Act

Answer 20

U.S. law prohibiting health insurers from using genetic information to make decisions about health-insurance coverage and rates; prevents employers from using genetic information in employment decisions; also prevents health insurers and employers from asking or requiring a person to take a genetic test.