Download Genetics 2008

Genetics 2008
Chapter 1 - Classical Genetics - Prof. Zaltsberg
1. What is are the chances for a family with 4 children, where both parents are
carriers of the recessive disease phenylketonuria (PKU), two of the children
were born with the disease, and two were born healthy (the order doesn't
matter)?
a. 0.0625
b. 0.375
c. 0.5
d. 0.21
2. The following statements deal with meiotic division of cells. Which of the
statements is not correct?
a. During the meiotic division, both inter-chromosomal (between the
chromosomes) and intra-chromosomal (within the chromosomes)
recombination take place
b. During the meiosis process, homologous chromosomes attach to each
other in a way that linked genes always pass together to the same
gamete
c. During meiosis there is an equal and random division of homologous
chromosomes to the gametes
d. During meiosis there is reduction in the number of chromosomes
3. What is correct regarding heteromorphic sex chromosomes?
a. Heteromorphic sex chromosomes are unique to vertebrate (including
birds, reptiles, amphibians and mammals)
b. In some organisms there is inactivation of X chromosome in the
females, and in some organisms there is hyper activation of X
chromosome in males
c. Heteromorphic sex chromosomes do not undergo pairing during
meiosis
d. In some animals there is hyper activation of X chromosome in males
e. The sex is determined by the XY system in all the animals
4. The genes A and B are independent, showing full co-dominancy between the
alleles of each. Dihybrid crossbreeding between mice heterozygous to both
characters (A and B) was performed. What phenotype ratio would you expect
between the offsprings?
a. 1:2:2:4:1:2:1:2:1
b. 9:3:3:1
c. 12:3:1
d. 1:1:1:1
-1-
5. A color-blind man (sex linked) marries a woman, who is carrier of hemophilia
(sex linked). What is the probability that their first child would suffer from
hemophilia or be color-blind?
a. 50%
b. 100%
c. 75%
d. 25%
e. 0%
6. Genetic screening of drosophila flies showed two recessive mutations
(mutation A and mutation B) that cause the phenotype of neural loss in the
peripheral nervous system. In order to find out whether those are two
mutations affecting the same gene, complementation tests were performed
between flies heterozygous to mutation A and flies heterozygous to mutation
B. Which of the following ratios between the offspring will indicate that the
mutations are not allelic?
a. 3:1
b. 9:3:3:1
c. 1:2:1
d. Both a and b are correct
e. All the offspring would be normal
7. In mice, X0 genotype is a fertile female, while Y0 mice cannot develop. What
is the expected gender ratio between the adult offspring of an X0 female with
a normal male?
a. Twice as much females as males
b. Twice as much males as females
c. Equal numbers of males and females
d. Females - three times the number of males
8. A woman with B blood type has a child with AB type and another child with
O type. During the divorce process, the husband has argued that he is not the
father of the second child (O type), but the woman's lover outside the marriage.
Which of the following would decline the husband's argument?
a. Both parents of the woman have B type blood
b. The parents of the husband are type A (the mother) and type O (father)
c. The lover's blood type is A
d. Both parents of the lover have AB blood type
-2-
9. Following is the biochemical pathway for production of red pigment in
snapdragon flowers: colorless original substance is converted into colorless
intermediate substance by enzyme A. The intermediate substance is converted
into yellow substance by enzyme B, and the yellow substance is converted
into the red pigment by enzyme C. The enzymes A, B, C are encoded by genes
A, B, C, respectively. Recessive alleles of the genes do not encode active
enzymes. What is the numeric ratio of the offspring of the following breeding:
AaBbCC X AaBbCc ?
a. 9 red, 0 yellow, 7 white
b. 9 red, 3 yellow, 4 white
c. 4 red, 3 yellow, 9 white
d. 27 red, 9 yellow, 28 white
e. 21 red, 16 yellow, 27 white
f. None of the above
10. Dihybrid breeding that tested two different characteristics showed phenotype
ratio of the offspring of 12:3:1. This ratio indicates:
a. Dominant epistasis
b. Recessive epistasis
c. Dominant suppression
d. Partial dominancy
e. Complementation between the tested genes
11. Corn snakes' skin color is determined by two biochemical pathways - one is
responsible for orange pigment production, and the other for black. In the
orange pathway, the dominant O allele enables the pigment production, while
the recessive allele does not. In the black pathway, the dominant B allele
enables the pigment production, while the recessive does not. Breeding of an
orange snake with a black snake (from pure races) produces "natural" colored
snakes at the F1 generation. What will happen at the breeding in F2
generation?
a. About half of the snakes would be "natural" color
b. Most of the snakes would be orange or black
c. Albino snakes would appear as well
d. The ratio would be 1:2:1 between orange, "natural" and black snakes
12. A pea plant has the following genotype - Abc/aBC. The map distance between
A and B is 20 centimorgan, and the map distance between B and C is 30
centimorgan. There is no genetic interruption at this chromosomal area. If you
perform self-breeding of this plant (meaning fertilization of the pestle with the
stamen of the same plant), what percent of the offspring is expected to show
recessive phenotype to all the three characters?
a. About 4% of offspring
b. About 2% of offspring
c. About 0.5% of offspring
d. About 6% of offspring
-3-
13. At a breeding farm of certain race shepherd dogs, dogs with brown fur (pure
race) were cross-bred with dogs with white fur (pure race as well). All the
cubs of F1 generation were white. When dogs of the F1 generation were crossbred with each other, the following offspring were obtained: 118 white dogs,
32 black dog and 10 brown dogs. What is correct, regarding the results?
a. Two genes are involved in the color determination. In the first
generation dogs from pure races were cross-bred. Each was
homozygous recessive for one of the genes and homozygous dominant
for the other
b. Two genes are involved in the color determination. One of the genes
shows dominant epistasis over the other gene
c. The allele that is responsible for the white color dominantly suppresses
the allele that is responsible for the brown pigment production
d. The allele for brown pigment is a dominant allele
14. In 10% of all the meioses in guinea pigs there is recombination between A and
B loci. What is the genetic map distance between those two genes?
a. 20 centimorgan
b. 10 centimorgan
c. 5 centimorgan
d. 50 centimorgan
15. What is correct regarding genetic recombination?
a. The sign of interchromosomal (between chromosomes) recombination
is that less than 50% of the meiosis products are recombinant
b. The more is the distance between genetic loci, the less is the chance for
recombination between them
c. If after meiosis there are 50% of recombinant products, it means that
the tested loci are located on separate chromosomes
d. Meiotic recombination is a process that produces haploid products that
have different genotype than the haploid genotypes comprising the
diploid meiotic cell
16. The following results have been attained following tri-hybrid test breeding of
AaBbCc:
ABC
310
abc
328
Abc
52
aBC
60
ABc
113
abC
99
AbC
18
aBc
20
In total there were 1000 offspring. What is the genetic map distance between A
and C?
a. 36.2 centimorgan
b. 15 centimorgan
c. 25 centimorgan
d. 40 centimorgan
-4-
In questions 17-20 choose from the options a-d the most probable inheritance
pattern for the pedigree representing a family with a rare disease:
a. Autosomal recessive
b. Autosomal dominant
c. Recessive X-linked
d. Dominant X-linked
17. Picture number 1:
-5-
18. Picture number 2:
-6-
19. Picture number 3:
20. Picture number 4:
-7-
Chapter 2 - Human Inheritance - Dr. Louder
21. While calculating probability according to Bayes rule, the posterior probability
is:
a. The calculated probability after dividing the joint probability by Bayes
factor
b. The probability inverse to the real probability
c. The prior probability before the multiplication by probabilities based
on additional data
d. The prior probability after multiplication by probabilities based on
additional data
e. The probability of inheritance of diseases that are only X-linked
22. A new test was developed for checking the carriage of a sick allele of a rare
and severe disease in humans. The test is based on a direct DNA investigation.
What is correct regarding the preference of the new test on calculation of the
probability of the allele existence by Bayes method?
a. DNA testing is cheaper
b. DNA testing is faster
c. Bayes method is preferred for prenatal counseling
d. The Bayes method is especially useful for an adopted kid
e. In most cases DNA test is more precise
23. Alleles are spread among populations and different ethnic groups in various
frequencies. Which of the following diseases is caused by an allele that is rare
among whites and common among blacks (for example Afro-Americans)?
a. Cystic fibrosis
b. Tay-Sachs
c. Sickle cell anemia
d. Retinal atrophy
e. Familial Mediterranean Fever
24. Survival of a new mutation in the population depends on random chance
("luck") and selective powers. In a small population, the rate of a specific allele
is supposed to change from generation to generation only according to luck, as
random events have relatively large effect. This phenomenon is called:
a. Genetic flow
b. Genetic bottleneck
c. Evolution
d. Stratification
e. Genetic drift
25. Coefficient of inbreeding (F) of a child, whose parents are second degree
cousins, is 64. This number reflects the:
a. Number of relatives with any genetic disease
b. Average number of sick alleles that is expected in the child's genome
c. Number of times that the sick allele has switched from the maternal to
the paternal chromosome
d. Inverse of the probability that the child is homozygous to an allele that
is inherited from the generation of the common grandparents of both
parents
e. Number of genes that are similar between the child and his parents
-8-
26. A survey study was performed regarding a gene with 2 alleles - A and B. The
homozygotes for the A allele are 28% of the screened population, and those for
the B allele are 8%. Which of the following explanations is reasonable?
a. There is a selective force for A homozygotes
b. There is a selective force for heterozygotes
c. There is a selective force for B homozygotes
d. There is no selective force for any genotype
e. There is not enough information for answering this question
27. An inherited defect that passes by multi-factorial inheritance is more common
in girls than in boys. Who has the highest chance to have the defect?
a. A daughter of a woman with the defect
b. A son of a woman with the defect
c. A daughter of a man with the defect
d. A son of a man with the defect
e. All of the above have similar chances
28. The concordance rate of a specific disease was checked for monozygotic (MZ)
twins and dizygotic (DZ) twins. It was found that the concordance rate in MZ
is 100%, and in DZ is 50%. What is the correct conclusion?
a. The disease is not genetic
b. The disease is passed in autosomal dominant inheritance
c. The disease is passed in mitochondrial inheritance
d. The disease is passed in autosomal recessive inheritance
29. Following are several statements regarding the importance of identification of
the genetic basis of composite diseases. Which of the statements is incorrect?
a. Identification of the genetic basis enables defining the risk of an
individual for developing the disease
b. As it is difficult to change the environment or the lifestyle, there is a
need for changing the defective gene
c. Identification of the genetic basis helps better understanding the
pathogenesis of the disease
d. Identification of the genetic basis enables more efficient follow-up for
individuals at risk
e. Identification of the genetic basis will enable more appropriate use of
the healthcare system resources
30. All of the following are characteristics of a compound disease, except:
a. Partial penetration of the mutation
b. Existence of phenocopies
c. The treatment is compound, as it includes genetic and environmental
treatment
d. High rate of sick alleles in the population
e. High variability of the genes in the population
31. Association investigations are performed in order to identify genes that are
involved in compound diseases. What is correct?
a. Such investigations are the most successful in a small and genetically
isolated population
b. There is no need to know in advance of an affinity between a gene or a
marker and the disease
c. It is better when the rate of the sick alleles in the investigated
population is low
d. They are best when performed upon an old and genetically diverse
population
e. They are best when performed upon a population with a wide
environmental and cultural diversity
32. Maternal inheritance is characterized by:
-9-
a.
b.
c.
d.
Only girls are sick
Only girls are carriers and only boys are sick
Boys pass on the disease only if their mothers were sick
The rate of passage from a mother to her daughter depends on the
father's phenotype
e. Only girls pass on to the next generation
33. What is correct regarding mitochondrial DNA?
a. Resembles the DNA of the viruses
b. Does not include introns
c. Is about 10% of all the DNA in the cell
d. Comprises only about 250 genes
e. Is more stable than the nuclear DNA
34. Genetic mosaic is:
a. DNA that is composed of 4 types of bases
b. A chromosome that is composed of DNA and RNA
c. A protein that is composed according to information from at least 2
separate genes
d. Protein system that is composed according to information from 2
separate genomes
e. A gene that contributes information to at least 2 proteins
35. Which of the following is incorrect regarding the definition of inborn error of
metabolism?
a. Metabolic change with pathological consequences
b. There are biochemical changes in the body
c. The disease always presents early after birth
d. There is an obstruction at a metabolic pathway
e. There is an enzymatic defect in a protein or co-factor
36. Most inborn metabolic defects are inherited in a recessive inheritance. The
reason for this is:
a. Because most of the sick individuals are cousins
b. Because dominant diseases are rare
c. There are actually quite a lot diseases that are passes by non recessive
inheritance, but they haven't been discovered yet due to technical
reasons
d. Because there is an evolutionary preference to recessive diseases
e. Because there is a large enzymatic reserve, thus there is no clinical
presentation in the case of 50% decline in the amount of the enzyme
37. Diseases of the mitochondrial chromosome damage the body, because of:
a. "Garbage" storage
b. Lack of energy production
c. Excess of substrates
d. Lack of vitamins
e. Poisoning of enzymes by lactic acid
-10-
38. Prenatal counseling is difficult for diseases of the mitochondrial chromosome,
because:
a. Mutations of the mitochondrial chromosome cannot be identified
b. The mitochondrial DNA in the fetus is unstable and changes during the
pregnancy
c. It is difficult to explain the character of the disease to the patients
d. The heteroplasmy phenomenon disables exact prediction of the rate of
disease passage or severity
e. The damage is done before the mother knows she is pregnant
39. All of the following are currently available strategies for genetic treatment,
except:
a. Insertion of a normal gene into the cells
b. Fixing of the defective gene
c. Replacing the defective gene
d. Blocking the defective RNA
40. What is incorrect regarding usage of viruses as vectors for genetic treatment?
a. Viruses are relatively efficient, as they are naturally infecting cells and
inserting genetic material
b. It is dangerous to work with viruses as they can change their
characteristics during the treatment
c. The dangers of viruses are only theoretical, as in the meanwhile, no
complications have occurred
d. RNA viruses can insert DNA into the genome
e. Most of the investigation in the area of genetic treatment is done with
viral vectors
-11-
Chapter 3 - Molecular Genetics - Dr. Ben-Yossef
41. The following question is related to picture number 5:
In a family with relatives' marriage there is an inherited disease with an
autosomal recessive pattern. A whole genome scan was performed and the
disease was mapped to a certain chromosomal area. Presented are 4 siblings
from the family and the genotype of each, with 4 markers that are located in
the critical interval of the disease. A, B and C are different alleles of each of
the markers. According to this data, what can be said regarding the location of
the disease-causing gene?
a. The gene is located between markers number 1 and number 4
b. The gene is located between markers number 1 and number 3
c. The gene is located between markers number 2 and number 3
d. The gene is located between markers number 2 and number 4
42. You have performed a sequence analysis of a certain gene in a person with a
genetic disease. You have found a substitution of C with G, located at the third
base of codon number 17 in the sequence that encodes the protein product of
the gene. The change has caused substitution of the codon for amino acid
serine with arginine. What can you say regarding this change?
a. It can be nonsense type mutation
b. It is certainly missense type mutation
c. It is certainly pleomorphism
d. It can be missense type mutation
-12-
43. In which of the following genetic diseases do you think that carriage tests can
be performed by simply biochemical serum analysis?
a. Ataxia telangiectasia is an autosomal recessive disease, caused by
mutation of the ATM gene that encodes a protein that is part of the
DNA fixing process and cell cycle control
b. DFNB 1 is a type of autosomal recessive genetic deafness, caused by a
mutation at the gene that encodes connexin 26 - a protein comprising
intercellular junctions of the gap junctions type
c. Hunter syndrome is a recessive metabolic X-linked disease that is
caused by mutations in the gene that encodes iduronate-2-sulfatase - a
lysosomal enzyme that is responsible for one of the stages of
glycosaminoglycans catabolism
d. Duchenne muscular dystrophy is an X-linked recessive disease, that is
caused by mutation at the dystrophin gene, encoding for a protein that
is an important component in the muscle tissue
44. The following question is related to picture number 6:
CDH23 is a gene that encodes for a protein that is important for intercellular
linkage, and which activity is calcium dependent. PAMP is a gene that
encodes a cellular calcium pump. In the presented family, there is a genetic
hearing loss, inherited in autosomal recessive pattern. The family members,
who suffer from hearing loss, can be divided into two phenotypic groups:
slight hearing loss (marked gray) and severe hearing loss (marked black). The
picture presents genotypes of the family members for both genes. P and L are
different alleles of the CDH23 gene, while A and V are the different alleles of
the PAMP gene. What can be stated regarding the cause of hearing loss in this
family?
a. The primary cause of hearing loss in the CDH23 gene, while the PAMP
gene serves as a modifier
b. The primary cause of hearing loss in the PAMP gene, while the CDH23
gene serves as a modifier
c. The cause of the hearing loss is the CDH23 gene, while the PAMP gene
does not affect the phenotype
d. Both genes serve as modifiers
-13-
45. Following is a DNA sequence that is part of the encoding sequence of a gene:
CTGACAAATCGG. At an individual, the gene was sequenced, and the
following sequence was found: CTGACAAATTCGG. How would you define
this change?
a. Point mutation
b. Splicing mutation
c. Frame shift
d. Deletion
46. In a family there are two children - a boy with the fragile X syndrome, and a
healthy girl. Cytogenetic analysis has showed that both children have inherited
from their mother the X chromosome with the fragile site. What is the most
reasonable explanation for this finding?
a. Fragile X syndrome is only inherited from a mother to her son, but not
from a mother to her daughter
b. Fragile X syndrome is only inherited from fathers to daughters
c. The penetration of fragile X syndrome is 80% in girls and only 30% in
boys
d. The penetration of fragile X syndrome is 80% in boys and only 30% in
girls
47. You are investigating an autosomal dominant genetic disease. Which of the
following findings can help you determine whether a candidate gene is indeed
the cause of the disease?
a. Mice carrying a damaged copy of the gene in the heterozygous state
present with the disease phenotype
b. The gene is very conserved through evolution
c. The level of the protein encoded by the gene in the cells of diseased is
equal to its level in the cells of healthy
d. In a certain diseased individual, a change in the sequence of the gene
was found in the heterozygous state. The same change is present in his
healthy sister
-14-
48. The following question is related to picture number 7:
Presented is a composite VNTR analysis performed upon the DNA of 3
individuals. Number 1 is the mother of number 2. What can be said with high
probability regarding number 3?
a. Number 3 is the identical twin of number 2
b. Number 3 is the brother of number 1 (from same mother and father)
c. Number 3 is the brother of number 2 (from same mother and father)
d. Number 3 is the father of number 2
49. More than 95% of the genome does not encode proteins. Which of the
following statements is incorrect?
a. The non-encoding sequence includes genes
b. The non-encoding sequence does not include genes
c. Part of the non-encoding sequence is located inside the genes
d. Part of the non-encoding sequence is located between the genes
50. The anticipation phenomenon is characteristic for inheritance of genes of the
following type:
a. Genes upon X chromosome
b. RNA-encoding genes
c. Genes that include repeating sequences that can undergo expansion
d. Genes with a dominantly transferred mutations
-15-
51. The RFLP analysis is based on the following principle:
a. The running pattern of a PCR product that includes a mutation in the
one-stranded state is different from that of a normal product
b. The mutation creates or cancels the restriction
c. PCR product that includes the mutation will undergo hybridization
only with oligo that has similar sequence as the product
d. In order to get the PCR product, the 3' side of the primer must be
complimentary to the template
52. Which of the following factors does not influence the mutation rate of a gene?
a. The sequence of the gene
b. The size of the gene
c. Parent's age
d. Baby's gender
53. A certain family comprises 10 individuals with a severe genetic disease. A
whole genome scan was performed in the family in an attempt to map the gene
that causes the disease. The maximal LOD score for the marker D1S223,
located on chromosome 1, was 1.8. What can be concluded from this finding?
a. The gene that causes the disease in this family is located on
chromosome 1, close to the marker D1S223
b. The gene that causes the disease in this family is located on
chromosome 18, close to the marker D1S223
c. The gene that causes the disease in this family is not located close to
the marker D1S223
d. The gene that causes the disease in this family is not located on
chromosome 1
54. Which of the following is incorrect?
a. Repeating sequences are always located in areas that do not encode for
protein
b. Repeating sequences may be part of genes control sequences
c. Repeating sequences serve as marker for genetic analyses
d. Repeating sequences may cause genetic diseases
55. Color blindness for red or green is a classical example for a genetic
disturbance caused by:
a. Instability of repeating sequences
b. Point mutation
c. Unequal recombination between chromosomes
d. X chromosome inactivation
56. The open reading frame of a gene is included in the exons, and continues:
a. From the initiation codon till the termination codon
b. From the termination codon promoter
c. From the promoter for polyadenylation signal
d. From the initiation codon till the polyadenylation signal
57. The Kozak consensus relates to:
a. A sequence in the boundaries of exon-intron
b. A sequence around the initiation codon
c. A sequence around the termination codon
d. A sequence in the promoter area
-16-
58. In a large family, 8 members are sick with a genetic autosomal dominant renal
disease. The disease was mapped to a critical interval on chromosome 9.
Analysis of a certain gene in the critical interval has shown a stop mutation
that was present in a heterozygous manner in all the sick family members.
Surprisingly, the same mutation was found in one of the healthy members.
What is the possible explanation for this finding?
a. Phenocopy
b. Genetic heterogeneity
c. Anticipation
d. Partial penetration
59. One of the types of familial isolated growth hormone deficiency is caused by
lack of one exon of a gene at chromosome 17. As a result of this deficiency, the
structure of the protein product is altered. In heterozygotes, the mutant protein
links with the normal protein and deactivates it. The most precise description
of this phenomenon is:
a. Loss of function mutation
b. Haploinsufficiency
c. Dominant negative effect
d. Gain of function mutation
60. In a search for a disease causing gene, you've found a certain change in a
gene's sequence, which appeared in several sick individuals, but not in healthy
ones. The change you've found is located on one of the introns of the gene.
Can this change be the mutation causing the disease?
a. Yes, if this is an evolutionary conserved intron
b. Yes, for example if it affects a splicing site
c. No, as mutations that cause disease are only the ones located on exons
d. No, as mutations that cause disease are only the ones located on
encoding sequences
-17-
Chapter 4 - Clinical Cytogenetics - Dr. Falick
61. Upon amniotic fluid examination due to the family request - without medical
justification - a balanced "de novo" reciprocal translocation was found. The
risk for defects and/or retardation of the fetus is:
a. Around 10%
b. Around 7%
c. The risk cannot be calculated
d. Close to 20%
62. Which of the following translocations is exceptional?
a. 22:15
b. 13:14
c. 21:21
d. 21:14
e. 9:22
63. Which of the following mechanisms is the most common as the cause of UPD?
a. Chromosomal duplication in an aneuploid zygote
b. Crossing over at a site that is not imprinted
c. Deletion at the imprinting center
d. Fertilization of an egg with diploid sperm
e. Loss of a chromosome from an aneuploid zygote
64. Genetic mosaic is usually characterized by all of the following, except:
a. The source of the cells from two separate zygotes
b. The source of the cells from one zygote
c. The phenomenon is exampled in many skin diseases
d. Presence of two cells populations in the same individual
e. The numerical ratio between the two cell lines contribute to the
phenotype of the individual carrying the mosaic
65. A couple has a baby with Down syndrome. At the karyotype examination, a
21q21q translocation was found, inherited by the baby from the mother. During
genetic counseling for the next pregnancy, you'd tell the parents that:
a. The chance for another baby with Down syndrome is close to zero
b. The chance for another baby with Down syndrome is 100%
c. The chance for another baby with Down syndrome is 25%
d. The chance for another baby with Down syndrome is 50%
e. The chance for another baby with Down syndrome is around 15%
66. Teratoma is a tumor comprising many different fetal tissues, originating in:
a. A fertilized egg with chromosomal composition of 46, XX
b. A fertilized egg with chromosomal composition of 46, XY
c. A fertilized egg with chromosomal composition from maternal origin
only
d. A fertilized egg with chromosomal composition from paternal origin
only
e. A fertilized egg with triploid or tetraploid chromosomal composition
67. A defect in the genomic imprinting gene causes diseases, such as:
a. Shprintzen syndrome
b. Cri-du-chat syndrome
c. Trisomy 18
d. Prader-Willi syndrome
e. Turner syndrome
-18-
68. The medical indications for karyotype testing include all the following,
except:
a. Recurrent miscarriage
b. Multiple defects in the newborn
c. Balanced translocation in the fetus that has been detected in the
amniotic fluid
d. A 17 years old girl, who hasn't got menses yet
e. A newborn with sole cleft palate
69. Parents with normal chromosomal composition gave birth to a baby with
karyotype 47, XYY. No evidence of mosaic was found. In whom of the parents
and at what stage did the non-disjunction happen?
a. Maternal meiosis at the first or second division
b. Maternal meiosis at the second division
c. Paternal meiosis, second division
d. Paternal meiosis, first division
e. Paternal meiosis, first or second division
70. You were called for counseling in the preterm babies ward for a baby boy that
was born with a small head, severe muscle weakness and lack of will to eat.
You have asked for chromosomal evaluation, and got the following picture:
The most appropriate interpretation of the picture is:
a. Normal male karyotype
b. Male karyotype, characteristic of Kleinfelter syndrome
c. Male karyotype including reciprocal translocation
d. Male karyotype including Robertsonian translocation
e. Male karyotype including inversion
-19-
71. The following karyotype was obtained from amniotic fluid examination that
was performed due to the mother's age. What will you tell the worried parents?
a.
b.
c.
d.
e.
Their son is expected to be crippled and retarded
Their son is expected to be healthy
Their son is expected to be infertile
Most chances are that this fetus will not survive till the birth
Their son is expected to develop a malignant tumor in the eye
-20-
72. Following is a karyotype picture. What is the correct description of the
findings?
a.
b.
c.
d.
e.
46, XX
46, XX, t(5:12)(p23:p24)
46, XX, t(5:12)(q23:p24)
46, XX, r12
47, XX, +12
-21-
73. At FISH examination of chromosomes the following picture was obtained:
The results of the test support the diagnosis of:
a. Shprintzen syndrome
b. Angelman syndrome
c. Prader-Willi syndrome
d. Cri-du-chat syndrome
e. Kleinfelter syndrome
74. A girl with chromosomal composition of 47, XXX is:
a. Higher than the average
b. Usually has normal IQ
c. In most cases will be infertile
d. Suffers from multiple congenital defects
e. Has a high chance to give birth to a baby with abnormal chromosomes
number
75. Mutations at mismatch repair genes are characteristic of tumors:
a. Breast and ovary tumors
b. Eye tumors
c. Polypous tumors of the gastrointestinal tract
d. Non-polypous tumors of the GI tract
e. Chronic myeloid leukemia
-22-
76. A 39 years old woman performs an amniotic fluid karyotype examination. The
fetal karyotype comprises chromosomal rearrangement in all the cells.
Examination of the parents' karyotypes - both are normal. Which of the
following fetal karyotypes has the highest risk for severely ill fetus?
a. 46, XX, t(13:14)
b. 46, XY, t(4:12) - balanced
c. 46, XY, inv2q - balanced
d. Boy with 47 chromosomes, one of which is a small bisatellite marker
that is positive for centromere 15 and negative for Prader-Willi locus at
FISH examination
e. Girl with 47 chromosomes, one of which is a large chromosomal
marker that is positive for centromere X and positive for locus XIST at
FISH examination
77. A 34 years old woman is pregnant. At week 12 nuchal translucency was normal.
Later, a compound risk of 1:500 for Down syndrome was calculated.
Ultrasonographic examination at week 20 was normal. The woman decided to
perform amniotic fluid examination, and the result shows structural change in
chromosomes 5 and 10. The couple arrives to a genetic counseling and
expresses the will to stop the pregnancy if the fetus has a high risk of mental
retardation. What would you suggest?
a. Write a letter to the committee for stopping pregnancy, explaining the
risk of mental retardation and other defects
b. Refer the couple for karyotype examination of the parents for the
continuation of investigation
c. Suggest repeating the amniotic fluid examination
d. There is no need for further investigation
e. CGH test is suggested anyway, as part of the investigation
78. Which of the following measures are not accepted for reducing the risk of
disease in women, who are carriers of the BRCA1/2 mutation?
a. Preventive oophorectomy (removal of the ovaries)
b. Preventive mastectomy (removal of the breasts)
c. Examination of the colon using an optical fiber for presence of polyps
once in two years
d. Vaginal US examination of the ovaries once in 3 months
e. Self examination of the breasts monthly
79. CGH (comparative genomic hybridization) testing will find only the
following:
a. 45,XX,der(13:14)(q10:q10)
b. 46,XX,inv(1)(p12:q22)
c. 46,XX,t(1:3)(p13:q21)
d. 46XY, ins(4:9)(p12:q21:q22)
e. 46,XY,del(4)(q22)
80. A child was born with partial deletion and duplication of the same
chromosome. The parental chromosomal defect that has lead to this
presentation is probably:
a. Isochromosome
b. Paracentric inversion
c. Balanced Robertsonian translocation
d. Pericentric inversion
e. Balanced reciprocal translocation
-23-
Probable answers:
41. c
42. d
43. c
44. a
45. c
46. d
47. a
48. c
49. b
50. c
51. b
52. d
53. c - question cancelled
54. a
55. c
56. a
57. b
58. d
59. c
60. b
61. question cancelled
62. e
63. e
64. a
65. b
66. c
67. d
68. e
69. c
70. c
71. b
72. d
73. a
74. b
75. d
76. a
77. b
78. c
79. e
80. d
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
-24-
d
b
d
a
d
e
a
d
a
a
c
c
b
c
d
d
b
c
b
a
a
e
c
e
d
b
c
c
b
c
a
e
b
d
c
e
b
d
a
c