Chapter 2

Question 1

The most common chromosomal abnormalities in abortuses are

Answer 1

1. 45
2. X (Turner syndrome)
3. Triploidy
4. Trisomy 16

Question 2

Translocations are particularly common between chromosomes

Answer 2

13,14,15,21 and 22 because they cluster during meiosis

Question 3

Is caused by an extra copy of chromosome 21 (trisomy 21)

Answer 3

Down syndrome

Question 4

Features of children with down syndrome include

Answer 4

Growth retardation

Varying degrees of intellectual disability

Craniofacial abnormalities including upward slanting eyes, epicanthal folds, flat faces, small ears

Cardiac defects and hypotonia

High chance of developing leukemia, infections, thyroid dysfunction, and premature aging.

Question 5

Down syndrome is caused by

Answer 5

Trisomy 31 resulting from meiotic nondisjunction, and in 75 percent of these instances, nondisjunction occurs during oocyte formation.

Question 6

Kids w Trisomy 18 has the following features

Answer 6

1. Intellectual disability
2. Congenital heart defects
3. Low set ears
4. Flexion of fingers and hands

Patients also show micrognathia, renal anomalies, syndactyly, and malformations of the skeletal system.

Question 7

The incidence of trisomy 18 is

Answer 7

Approximately 1 in 5000 newborns. 85 percent are lost between 10 weeks of gestation and term. Those born alive usually die by 2 months of age. Approx 5 percent live beyond 1 year.

Question 8

The main abnormalities of trisomy 13 are

Answer 8

1. Intellectual disability
2. Holoprosencephaly
3. Congenital heat defects
4. Deafness
5. Cleft lip and palate
6. Eye defects such as microphthalmia, anophthalmia, and coloboma.

Question 9

The incidence of trisomy 13 is

Answer 9

1 in 20000 live births and more than 90 percent of the infants die in the first month. Approx 5 percent live beyond 1 year.

Question 10

Birth defect found only in males and usually detected by amniocentesis

Answer 10

Klinefelter syndrome

Question 11

Clinical features of Klinefelter syndrome

Answer 11

1. Sterility
2. Testicular atrophy
3. Hyalinization of the seminiferous tubules
4. Gynecomastia

Question 12

The incidence of Klinefelter syndrome is

Answer 12

Approximately 1 in 500 males.

Question 13

Absence of ovaries

Answer 13

Gonadal dysgenesis

Question 14

Abnormalities are webbed neck, lymphedema of the extremities, skeletal deformities, and a broad chest with widely spaced nipples.

Answer 14

Turner syndrome

Question 15

Frequently have problems with speech and self esteem. They have two sex chromatin bodies in their cells.

Answer 15

Triple x syndrome

Question 16

A well known syndrome cause by partial deletion of the short arm of chromosome 5

Answer 16

Cri-du-chat syndrome

Question 17

Cri-du-chat affected babies have

Answer 17

1. Cat like cry
2. Microcephaly (small head)
3. Intellectual disability
4. Congenital heart disease

Question 18

Approximately 55% of affected females are monosomic for the X and chromatin body negative because of

Answer 18

Nondisjunction (Turner syndrome) 80% of these females, nondisjunction in the male gamete is the cause

Question 19

When microdeletion occurs on the long arm of chromosome 15 and microdeletion occurs on the maternal chromosome

Answer 19

Angelman syndrome

Question 20

Angelman syndrome causes

Answer 20

1. Intellectual disability
2. Cannot speak
3. Exhibit poor motor development
4. Prone to unprovoked and prolonged periods of laughter

Question 21

Microdeletion on the long arm of chromosome 15 occurs in the paternal chromosome

Answer 21

Prader-Willi syndrome

Question 22

Prader-Willi syndrome

Answer 22

1. Hypotonia
2. Obesity
3. Intellectual disability
4. Hypogonadism
5. Undescended testes

Question 23

Characteristics that are differentially expressed depending upon whether the genetic material is inherited from the father or mother are examples of

Answer 23

Genomic imprinting

Question 24

Regions of chromosomes that demonstrate a propensity to separate or break under certain cell manipulation

Answer 24

Fragile sites