Genetic Disorders – Chapter 5

Question 1

An inactive X chromosome that can be seen in the interphase nucleus as a darkly staining small mass in contact with the nuclear membrane is a _________.

Answer 1

Barr body or X chromatin (p. 164)

Question 2

Define diploid.

Answer 2

having 2 sets of chromosomes

Question 3

Haploid

Answer 3

possessing half the diploid or normal number of chromosomes found in somatic or body cells

Question 4

aneuploid,

Answer 4

error in meiosis or mitosis in which a cell acquires a chromosome complement that is not an exact multiple of 23

Question 5

Euploid

Answer 5

any exact multiple of the haploid number

Question 6

What is mosaicism?

Answer 6

Mitotic errors in early development that give rise to two or more populations of cells with different chromosome complement in the same individual. (p. 159)

Question 7

Define Translocation

Answer 7

a segment of one chromosome is transferred to another

Question 8

Define Inversion

Answer 8

refers to a rearrangement that involves two breaks within a single chromosome with inverted reincorporation of the intervening segment

Question 9

Define Deletion

Answer 9

refers to a loss of a portion of a chromosome. (p. 160-161)

Question 10

The most common of the chromosomal disorders and a major cause of mental retardation is_______.

Answer 10

Trisomy 21 or Down Syndrome (p. 162)

Question 11

A female child has short stature, webbing of the neck, streak ovaries, widely spaced nipples, and coarctation of the aorta. What is the most likely karyotype?

Answer 11

45 X or Turner Syndrome (p. 166)

Question 12

Define Klinefelter syndrome

Answer 12

is best defined as male hypogonadism that occurs when there are two or more X chromosomes and one or more Y chromosomes. It is one of the most common causes of hypogonadism in the male. (p. 165)

Question 13

Define and discuss hermaphroditism and pseudohermaphroditism.

Answer 13

The term hermaphrodite implies the presence of both ovarian and testicular tissue. In contrast, a pseudohermaphrodite represents a disagreement between the phenotypic and gonadal sex. (p. 167)

Question 14

Discuss the 3 changes of Marfan Syndrome.

Answer 14

Marfan syndrome is a disorder of the connective tissues of the body, manifested principally by changes in the skeleton, eyes and cardiovascular system.
1. Skeletal – unusually tall with exceptionally long extremities and long tapering fingers and toes.
2. Ocular – ectopia lentis – bilateral subluxation or dislocation of the lens.
3. Cardiac – mitral valve prolapse and dilation of the ascending aorta owing to cystic medionecrosis; dilation of aortic root gives rise to severe aortic incompetence; aortic dissection with rupture is the leading cause of death in 30 to 45% of patients with Marfan syndrome (p. 144-145)

Question 15

Define Niemann-Pick A and B Disease

Answer 15

is characterized by lysosomal accumulation of sphingomyelin resulting from an inherited deficiency of sphingomyelinase.

Question 16

Define Gaucher Disease

Answer 16

is an autosomal recessive disorder resulting from mutation in the gene encoding glucocerebrosidase. It is the most common lysosomal storage disorder. (p. 152-153)