Chapter 2 Genes and Genetic Diseases

Question 1

Genetic diseases cause (3)

Answer 1

• Errors in duplication process
• Maternal age
• Environmental

Question 2

Types of generic diseases (2)

Answer 2

• Numerical abnormalities

- Structural abnormalities

Question 3

Numerical Abnormalities (3)

Answer 3

• Polyploidy
• Triploidy
• Aneuploidy

Question 4

Polyploidy

Answer 4

Having three or even four times the number of chromosomes

Question 5

Triploidy

Answer 5

Account for about 10% of miscarriages

Question 6

Aneuploidy

Answer 6

Abnormal number of chromosomes, usual 45 chromosomes instead of 46

Question 7

Structural Abnormalities (5)

Answer 7

• Deletions
• Duplications
• Translocations
• Inversions
• Rings

Question 8

Deletion

Answer 8

Portion of the chromosome is missing or deleted

Question 9

Duplication

Answer 9

Portion of the chromosome is duplicated, resulting in extra genetic material

Question 10

Translocation

Answer 10

Portion of one chromosome is transferred to another chromosome

Question 11

Inversion

Answer 11

Portion of the chromosome has broken off, turned upside down, and reattached

Question 12

Rings

Answer 12

A portion of a chromosome has broken off and formed a circle or ring

Question 13

Autosomal aneuploidy example

Answer 13

Down syndrome

Question 14

Down syndrome implications (6)

Answer 14

• Intellectual disability
• Low nasal bridge
• Epicentral folds
• Protruding tongue
• Low-set ears
• Poor muscle tone

Question 15

Diagnosis and management of down syndrome (3)

Answer 15

• Genetic testing
• Treat disorder such a heart abnormalities
• Average lifespan 49 years

Question 16

Sex Chromosome Aneuploidy examples (2)

Answer 16

• Turner syndrome

- Klinefelter syndrome

Question 17

Turner syndrome characteristics (6)

Answer 17

• Underdeveloped ovaries (sterile)
• Short stature
• Webbing of the neck
• Edema
• Underdeveloped breasts, wide nipples
• Learning difficulties

Question 18

Klinefleter Syndrome Characteristics (6)

Answer 18

• 2 X’s and 1 Y chromosome
• Male appearance
• Develop female like breasts
• Small testes
• Sparse body hair
• Long limbs

Question 19

Chromosome breakage

Answer 19

-Physiologic mechanisms will usually repair the break, but the breaks can heal in a way that alters the structure of the chromosome

Question 20

Castogens

Answer 20

Agents that increase risk of breakage

Question 21

Deletion

Answer 21

-Breakage or loss of DNA

Question 22

Cri du chat syndrome

Answer 22

• Deletion of short arm of chromosome

- Low birth weight, severe intellectual disability, and microephaly

Question 23

Signs and symptoms of cri du chat (5)

Answer 23

• Feeding problems because of difficulty swallowing and sucking
• Severe cognitive, speech, and motor delays
• Unusual facial features
• Behavioral problems
• Excessive drooling

Question 24

Modes of inheritance of single-gene diseases (4)

Answer 24

• Autosomal dominant
• Autosomal recessive
• X-linked dominant
• X-linked recessive

Question 25

Autosomal Dominant Inheritance (2)

Answer 25

• Affect offspring usually produced by union of normal parent with affected heterozygous parent
• Allele may be disease causing or normal

Question 26

Autosomal Recessive Inheritance (2)

Answer 26

• Trait is expressed only when the individual has both abnormal genes from the parent
• Parents may be unaffected carriers yet transmit the trait of the disease to their offspring
• The likelihood that two carries will mate is increased

Question 27

X-Linked Inheritance (2)

Answer 27

• Sex-linked: genetic conditions caused by mutations on sex chromosomes
• Usually expressed by males because females have another X chromosome to counteract the abnormal gene

Question 28

X-linked inheritance characteristics of pedigrees (4)

Answer 28

• Most X-linked disorders are recessive
• Affect males cannot transmit the genes to sons, but they can to all daughters
• Females become carriers for the disease
• Sons of female carriers have a 50% risk of be affected