Lecture 9

Question 1

Adermatoglyphia

Answer 1

The absence of ridges on the skin on the pads of the fingers and toes

Question 2

Special Features of Human Biology that Hinder Genetics Research

Answer 2

• Controlled mating is not possible
• Long generation time
• Small family size

Question 3

Pedigree

Answer 3

Pictorial representation of a family history; a family tree that outlines the inheritance of one or more characteristics

Question 4

Proband

Answer 4

The person from whom the pedigree is initiated

Question 5

Autosomal Recessive Traits

Answer 5

Appear with equal frequency in both sexes and seem to skip generations; examples include cystic fibrosis, sickle cell anemia, and Tay-Sachs disease

Question 6

Autosomal Dominant Traits

Answer 6

Normally appear with equal frequency in both sexes and do NOT skip generations; example is familial hypercholesterolemia

Question 7

X-Linked Recessive Traits

Answer 7

Appear more often in males than in females and are not passed from father to son; a recessive allele (like color blindness) is masked in a female with 2 X chromosomes; example is duchenne muscular dystrophy

Question 8

Y-Linked Traits

Answer 8

Appear only in males and are passed from father to all his sons; examples include male infertility, excessive hair on the ear pinna, retinitis pigmentosa, XYY syndrome

Question 9

Dizygotic Twins (Fraternal)

Answer 9

Nonidentical twins

Question 10

Monozygotic Twins

Answer 10

Identical twins

Question 11

Concordant Trait

Answer 11

A trait shared by both members of a twin pair; trait may not be exactly the same phenotypically due to differences in penetrance or other factors

Question 12

Concordance

Answer 12

The percentage of twin pairs that are the same (concordant) for a trait

Question 13

Chorionic Villus Sampling

Answer 13

Procedure for obtaining fetal cells for genetic testing;

1 - Under the guidance of ultrasound, a catheter is inserted through the vagina and cervix and into the uterus, where it is placed into contact with the chorion, the outer layer of the placenta
2 - Suction removes a small piece of the chorion
3 - Cells of the chorion are used directly for many genetic tests, and culturing is not required

Can be performed very early in pregnancy (10-11 weeks)

Question 14

Amniocentesis

Answer 14

Another procedure for obtaining fetal cells for genetic testing;

1 - Under the guidance of ultrasound, a sterile needle is inserted through the abdominal wall into the amniotic sac
2 - A small amount of amniotic fluid is withdrawn through the needle
3 - The amniotic fluid contains fetal cells, which are separated from the amniotic fluid and cultured
4 - Tests are then performed on the cultured cells

Question 15

Benefits of Genetic Testing

Answer 15

• Diagnosis
• Reduce testing
• Appropriate intervention (prevention, management, treatment)
• Informed decisions
• Reproductive choices

Question 16

Risks of Genetic Screening

Answer 16

• Risk of miscarriage
• Psychological impact
• Family relations
• Insurance issues/concerns
• Privacy