Deck 7: Sex Chromosome and Mitochondrial Inheritance and Disorders

Question 1

Which clinical feature in a newborn baby girl suggests the possibility of Turner syndrome?

A)Absence of Babinski reflex
B)Presence of a webbed neck
C)Presence of epicanthal folds
D)Absence of irises of both eyes

Answer 1

Presence of a webbed neck

Question 2

At what specific location on an X chromosome is a break most likely to occur in fragile X syndrome?

A)The centromere
B)End of the p arm
C)End of the q arm
D)Within the nucleosome

Answer 2

End of the q arm

Question 3

Which process can cause a person with an XY genotype to have a female phenotype?

A)Pregnancy resulting from artificial insemination in which the semen donor is homosexual
B)Mating of a man who has Klinefelter syndrome with a woman who has Turner syndrome
C)An epigenetic disorder in which the X chromosome inactivates the Y chromosome
D)Failure of gene expression resulting in a complete absence of androgen receptors

Answer 3

Failure of gene expression resulting in a complete absence of androgen receptors

Question 4

Which of the following mechanisms in fragile X syndrome (FXS) leads to expression of the disorder?

A)Trinucleotide repeat sequences interspersed with the exons of the FMR1 gene, resulting in the production of an abnormal protein
B)Trinucleotide repeat sequences causing methylation of the FMR1 gene, thus silencing its expression
C)Increased production of microRNA molecules that interfere with the transcription of the FMR1 gene
D)Increased production of microRNA molecules that interfere with the translation of the FMR1 gene

Question 5

Which trait or characteristic in a 10-year-old-girl would lead her pediatrician to consider the possibility of androgen insensitivity syndrome?

A)Her ears are large and stick out.
B)She is color-blind, and her father is not.
C)She is an inch taller than her siblings were at age 10.
D)Her nipples and breasts have not started to change and develop.

Question 6

What is the function of the FMR1 gene?

A)Promoting brain development and maintaining neuronal synapses
B)Ensuring the expression of all other genes present on the X chromosome
C)Preventing amyloid plaque deposits and formation of neuronal tangles in the brain
D)Maintaining the structural integrity of the histone proteins surrounding the X chromosome

Question 7

Which of the following definitions accurately represents the concept of expansion?

A)The phenotype of a genetic condition is expressed with greater severity and at earlier ages with succeeding generations.
B)The number of trinucleotide repeat sequences within the noncoding region of a specific gene allele is increased.
C)The number of copies of a specific gene allele is amplified on one chromosome of a homologous pair.
D)A specific gene allele has at least two copies of every exon within the gene.

Question 8

What is the risk for a man with a 47,XYY karyotype to produce a child with a 47,XYY karyotype?

A)100%
B)50%
C)25%
D)0%

Question 9

On which chromosome is the androgen receptor (AR) gene located?

A)1
B)21
C)X
D)Y

Question 10

Which condition or health problem is more common in women who have an FMR1 mutation?

A)Emotional instability with inappropriate expression of anger
B)Patchy areas of decreased skin pigmentation
C)Progressive skeletal muscle weakness
D)Menopause before age 40 years

Question 11

Which feature is common among people who have Klinefelter syndrome (47,XXY) or a karyotype with 47,XXX but not among people who have Down syndrome or Edward syndrome?

A)Severely reduced cognition
B)Cleft palate
C)Tall stature
D)Infertility

Question 12

Amale patient is tall and has some gynecomastia along with a low sperm count. During infertility testing, he was found to have a 47,XXY karyotype. Which disorder isconsistent with these findings?

A)Normal male
B)Turner syndrome
C)Klinefelter syndrome
D)Testicular feminization syndrome

Question 13

What factor most strongly influences the development of the paramesonephric tissue into female sex organs?

A)Proper positioning of the bipotential gonad
B)The presence of estrogen during puberty
C)The presence of two X chromosomes
D)The absence of a Y chromosome

Question 14

Which health screening activity is most important for girls and women with Turner syndrome?

A)Mammography
B)Test for osteoarthritis
C)Blood pressure screening
D)Pulmonary function testing

Question 15

A man and his sister are both affected with a mitochondrial disorder. Because the sister has two children who also have the disorder, the man is concerned about thepossibility of also having children with the disorder. What is the estimated risk for each pregnancy of this man producing a child with the same mitochondrial disorder that he has if his wife does not have a mitochondrial disorder?

A)100%
B)50%
C)25%
D)0%

Question 16

What is the most likely mechanism for a 45,X karyotype?

A)Anticipation
B)Nondisjunction
C)Expansion
D)Heteroplasmy

Question 17

Which single physical feature is most often associated with a 47,XXX karyotype?

A)Infertility
B)Large breasts
C)Female-pattern baldness
D)Height greater than siblings

Question 18

Why is the incidence of an extra Y chromosome in the general population unknown?

A)The phenotype is that of a normal male.
B)Most conceptions with 47,XYY are spontaneously aborted.
C)The life expectancy for males with 47,XYY is often short.
D)The majority of males with this sex chromosome abnormality are institutionalized.

Question 19

What would be the expected consequence to two daughter cells after mitosis if the ability to produce mitochondria was lost?

A)Cell commitment and differentiation would fail to occur.
B)The process of protein synthesis could not be controlled.
C)The rate and amount of ATP production would be limited.
D)Future cell division would result in an uneven number of cells.

Question 20

Which type of problem results from mutations in mitochondrial DNA (mtDNA)?

A)Reduced cellular energy
B)Balanced translocations
C)Excessive "crossing over"
D)Single-nucleotide polymorphisms