Question 1

Why is Down syndrome the most common trisomy disorder seen among live born infants?

Accepted Answer

A)  The extra alleles from trisomies of larger chromosomes are embryo lethal.
B)  Nondisjunction occurs more frequently for chromosome 21 than for any other chromosome.
C)  Trisomies resulting from nondisjunction express fewer alleles than trisomies that result from unbalanced translocations.
D)  The incidence may not be truly higher but is recognized more often because the features of a baby with trisomy 21 are more obvious and not missed as often as are the more subtle features of other trisomies. A

Question 2

A male 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 is consistent with these findings?

Accepted Answer

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

Question 3

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

Accepted Answer

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. C

Question 4

Which feature of a 15q deletion is present in both Angelman syndrome and Prader-Willi syndrome?

Accepted Answer

A)  Light skin,eye,and hair coloring
B)  Continuous smiling and jerky gait
C)  Excessive appetite and weight gain
D)  Progressive tremors and seizure activity

Question 5

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

Accepted Answer

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

Question 6

Why does an embryo with a balanced translocation have the same chance for normal development that an embryo with a normal karyotype has?

Accepted Answer

A)  The translocation stimulates DNA repair mechanisms to correct the problem before commitment occurs.
B)  The embryo's somatic cells are unaffected,expressing a normal karyotype;only germline cells express the translocation.
C)  Although the location of the genetic material is abnormal with a balanced translocation,there are no missing or extra alleles.
D)  When a zygote with a balanced translocation reaches the embryo stage without a spontaneous abortion,the risk for abnormal development decreases.

Question 7

How is a Robertsonian translocation different from a reciprocal translocation?

Accepted Answer

A)  A Robertsonian translocation is unbalanced,and a reciprocal translocation is balanced.
B)  A reciprocal translocation is unbalanced,and a Robertsonian translocation is balanced.
C)  Reciprocal translocations occur between whole acrocentric chromosomes,and Robertsonian translocations occur between any two nonhomologous chromosomes.
D)  Robertsonian translocations occur between whole acrocentric chromosomes,and reciprocal translocations occur between any two nonhomologous chromosomes.

Question 8

What is the risk for a woman who had a retinoblastoma in early childhood as a result of a partial deletion on one number 13 chromosome to have a child who also develops the disorder?

Accepted Answer

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

Question 9

Which statement regarding partial chromosomal deletions or duplications is true?

Accepted Answer

A)  They result in either a triple dose of some gene alleles or a single dose of some alleles.
B)  They usually result in fewer or milder manifestations than do trisomies or monosomies.
C)  The majority of partial chromosomal deletions or duplications result from advanced parental age.
D)  General prenatal chromosomal analysis has resulted in fewer children being born with these problems.

Question 10

What is the risk for a man who has Down syndrome to produce a child with Down syndrome with a woman who has a normal karyotype?

Accepted Answer

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

Question 11

Which type of problems result from mutations in mitochondrial DNA (mtDNA)?

Accepted Answer

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

Question 12

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

Accepted Answer

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

Question 13

Which factor has the greatest influence on the expression of a genetic disorder such as Prader-Willi syndrome or Angelman syndrome through the process of genomic imprinting?

Accepted Answer

A)  Paternal age at time of conception
B)  Maternal age at time of conception
C)  The gender of the parent transmitting the deletion
D)  The number of bases deletion from the chromosome

Question 14

Which clinical feature is a common finding for infants with trisomy 21,trisomy 18,and trisomy 13?

Accepted Answer

A)  Rocker bottom feet
B)  Single palmar crease
C)  Small,close-set eyes
D)  Cleft lip (with or without cleft palate)

Question 15

Which reproductive consequence is possible for a man who has a 13;15 Robertsonian translocation when his wife has a normal karyotype?

Accepted Answer

A)  He is unlikely to ever impregnate his wife.
B)  Because his wife has normal karyotype,there are no reproductive consequences.
C)  He has an increased risk for having a child born with either trisomy 13 or trisomy 15.
D)  He has an increased risk for having a child born with either monosomy 13 or monosomy 15.

Question 16

Which cancer type has an increased incidence among children with WAGR syndrome?

Accepted Answer

A)  Acute leukemia
B)  Brain tumors
C)  Colorectal cancer
D)  Nephroblastoma

Question 17

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

Accepted Answer

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 18

What is the best explanation of a child having the physical phenotype of Down syndrome but having a totally normal karyotype on chromosomal analysis of blood?

Accepted Answer

A)  Mosaicism of trisomy 21 in various tissues
B)  Inaccurate technique for chromosomal analysis
C)  Uniparental disomy for somatic cells but not for germ cells
D)  Selective chromosome loss during meiosis II of gametogenesis

Question 19

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 the possibility 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?

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 5: Chromosomal and Mitochondrial Inheritance and Disorders

Why is Down syndrome the most common trisomy disorder seen among live born infants?

A male 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 is consistent with these findings?

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

Which feature of a 15q deletion is present in both Angelman syndrome and Prader-Willi syndrome?

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

Why does an embryo with a balanced translocation have the same chance for normal development that an embryo with a normal karyotype has?

How is a Robertsonian translocation different from a reciprocal translocation?

What is the risk for a woman who had a retinoblastoma in early childhood as a result of a partial deletion on one number 13 chromosome to have a child who also develops the disorder?

Which statement regarding partial chromosomal deletions or duplications is true?

What is the risk for a man who has Down syndrome to produce a child with Down syndrome with a woman who has a normal karyotype?

Which type of problems result from mutations in mitochondrial DNA (mtDNA) ?

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

Which factor has the greatest influence on the expression of a genetic disorder such as Prader-Willi syndrome or Angelman syndrome through the process of genomic imprinting?

Which clinical feature is a common finding for infants with trisomy 21,trisomy 18,and trisomy 13?

Which reproductive consequence is possible for a man who has a 13;15 Robertsonian translocation when his wife has a normal karyotype?

Which cancer type has an increased incidence among children with WAGR syndrome?

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

What is the best explanation of a child having the physical phenotype of Down syndrome but having a totally normal karyotype on chromosomal analysis of blood?

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