ABGC Practice Questions Solved 100%
. Predispositional testing is:
A. Testing for a mutation that increases the risk of a specific disease based on family
history
B. Testing for a condition in which a person is showing symptoms
C. Testing for a condition with complete penetrance prior to the development of
symptoms
D. Testing for a condition to determine when a disease will occur
E. Testing for a mutation that is not inherited, but occurs sporadically during a person's
lifetime - ANSWER-A. Testing for a mutation that increases the risk of a specific disease
based on family history
A 10-year old Caucasian girl is brought in by her parents for a clinical genetics
evaluation of a skin disorder. The child has many freckles on her face, arms, and legs.
The parents were told by previous physicians that she suffers from xeroderma
pigmentosum and that they should limit her exposure to sunlight. What is the most likely
etiology of this disorder?
A. Deficient DNA replication
B. Impaired DNA repair by nucleotide excision
C. Defective RNA transcription from TATA-less promoter
D. Impaired ribosomal protein translation
E. Impaired DNA repair by photoreactivation - ANSWER-B. Impaired DNA repair by
nucleotide excision
A 12-year-old girl is referred to the genetics clinic because of a childhood history of
bilateral retinoblastoma. Due to her treatment in infancy with bilateral external beam
radiotherapy, which of the following additional cancers is she most likely to develop?
A. Breast cancer
B. Leukemia
C. Osteosarcoma
D. Pineal blastoma - ANSWER-C. Osteosarcoma
A 23-year-old woman has a baby with the karyotype 47,XY,+21. Which of the following
is the correct conclusion?
A. This woman's risk for having another baby with a chromosome abnormality is the
same as other women her age
B. Either the woman or her husband probably has a Robertsonian translocation
C. Either the woman or her husband probably has germ line mosaicism
D. Either the woman or her husband probably carriers a balanced reciprocal
translocation
E. Both members of the couple probably have normal chromosomes - ANSWER-E.
Both members of the couple probably have normal chromosomes
,A 25-year-old man is referred for a genetics evaluation with a chief complaint of
persistent, high-pitched ringing noises in his ears. Questioning reveals that he has also
been losing his balance lately. A head CT demonstrates bilateral tumors involving the
vestibulocochlear nerve. Which of the following chromosomes contains the tumor
suppressor gene most likely to be involved in this case?
A. 5q
B. 13q
C. 17q
D. 18q
E. 22q - ANSWER-E. 22q
A child with a cleft palate, heart defect, and extra fifth fingers is found to have 46
chromosomes with extra material on one homologue of chromosome 5. This
chromosome abnormality is best described by which of the following terms?
A. Polyploidy
B. Balanced rearrangement
C. Ring formation
D. Mosaicism
E. Unbalanced rearrangement - ANSWER-E. Unbalanced rearrangement
A couple has a child with achondroplasia, but both parents have average stature. What
is the best estimate of their chance of having another child with achondroplasia?
A. Less than 0.1%
B. 1-2%
C. 25%
D. 50%
E. 100% - ANSWER-A. Less than 0.1%
A couple have a severely affected son with Hunter syndrome, which is diagnosed by
assaying iduronate sulfatase. Two years later, they have a daughter with the same
severe condition and confirmed by enzyme assay. What would be the most important
next step in evaluating this family?
A. Enzymatic carrier testing for both of the parents
B. Determine paternity by HLA typing of the father
C. Take a careful pregnancy history to check for teratogenic exposures
D. Karyotype the daughter
E. Karyotype the parents - ANSWER-D. Karyotype the daughter
(note: Hunter syndrome is X-linked recessive)
A couple who recently had a daughter with a chromosome abnormality comes for
genetic counseling. Their daughter's karyotype is 46,XX,del(3)(p25.3). Both parents are
studied and their karyotypes are normal. The most accurate counseling is that: A. Small
deletions do not usually cause severe birth defects and mental retardation
, B. Although both parents have normal karyotypes, they could still have a small
increased chance of having another child with an unbalanced karyotype due to the
possibility of germ line mosaicism
C. The parental chromosome testing should be repeated since one parent should have
a balanced translocation to explain the deletion in the child
D. The proband's phenotypically normal siblings should be karyotyped to determine if
they are balanced translocation carriers
E. Because the deletion is de novo, the proband is less likely to have birth defects and
mental retardation than if it was inherited se - ANSWER-B. Although both parents have
normal karyotypes, they could still have a small increased chance of having another
child with an unbalanced karyotype due to the possibility of germ line mosaicism
A couple whose first son has isolated hydrocephalus with aqueductal stenosis asks
about their risk to have another affected child. There are no other affected individuals in
the family, and the boy has a normal karyotype. The chance that their next child would
be affected is closest to:
A. 1%
B. 3%
C. 6%
D. 12%
E. 25% - ANSWER-C. 6%
A diagnosis of Hunter syndrome is suspected. What is the most likely pattern of
inheritance?
A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive
D. Mitochondrial
E. X-linked dominant - ANSWER-C. X-linked recessive
A female neonate has profound hypotonia. The only known complication of pregnancy
was polyhydramnios. The mother has a lack of facial expression and weak muscles;
she says she did not have any problems as an infant or child. Which of the following
best explains the difference in presentations in the mother and child?
A. Anticipation
B. Delayed onset
C. Genetic heterogeneity
D. Incomplete penetrance
E. Pleiotropy - ANSWER-A. Anticipation
A full-length cDNA clone will contain sequences corresponding to each of the following
except:
A. Translation start codon
B. Exons
C. Poly-A tail
D. 5' untranslated region
. Predispositional testing is:
A. Testing for a mutation that increases the risk of a specific disease based on family
history
B. Testing for a condition in which a person is showing symptoms
C. Testing for a condition with complete penetrance prior to the development of
symptoms
D. Testing for a condition to determine when a disease will occur
E. Testing for a mutation that is not inherited, but occurs sporadically during a person's
lifetime - ANSWER-A. Testing for a mutation that increases the risk of a specific disease
based on family history
A 10-year old Caucasian girl is brought in by her parents for a clinical genetics
evaluation of a skin disorder. The child has many freckles on her face, arms, and legs.
The parents were told by previous physicians that she suffers from xeroderma
pigmentosum and that they should limit her exposure to sunlight. What is the most likely
etiology of this disorder?
A. Deficient DNA replication
B. Impaired DNA repair by nucleotide excision
C. Defective RNA transcription from TATA-less promoter
D. Impaired ribosomal protein translation
E. Impaired DNA repair by photoreactivation - ANSWER-B. Impaired DNA repair by
nucleotide excision
A 12-year-old girl is referred to the genetics clinic because of a childhood history of
bilateral retinoblastoma. Due to her treatment in infancy with bilateral external beam
radiotherapy, which of the following additional cancers is she most likely to develop?
A. Breast cancer
B. Leukemia
C. Osteosarcoma
D. Pineal blastoma - ANSWER-C. Osteosarcoma
A 23-year-old woman has a baby with the karyotype 47,XY,+21. Which of the following
is the correct conclusion?
A. This woman's risk for having another baby with a chromosome abnormality is the
same as other women her age
B. Either the woman or her husband probably has a Robertsonian translocation
C. Either the woman or her husband probably has germ line mosaicism
D. Either the woman or her husband probably carriers a balanced reciprocal
translocation
E. Both members of the couple probably have normal chromosomes - ANSWER-E.
Both members of the couple probably have normal chromosomes
,A 25-year-old man is referred for a genetics evaluation with a chief complaint of
persistent, high-pitched ringing noises in his ears. Questioning reveals that he has also
been losing his balance lately. A head CT demonstrates bilateral tumors involving the
vestibulocochlear nerve. Which of the following chromosomes contains the tumor
suppressor gene most likely to be involved in this case?
A. 5q
B. 13q
C. 17q
D. 18q
E. 22q - ANSWER-E. 22q
A child with a cleft palate, heart defect, and extra fifth fingers is found to have 46
chromosomes with extra material on one homologue of chromosome 5. This
chromosome abnormality is best described by which of the following terms?
A. Polyploidy
B. Balanced rearrangement
C. Ring formation
D. Mosaicism
E. Unbalanced rearrangement - ANSWER-E. Unbalanced rearrangement
A couple has a child with achondroplasia, but both parents have average stature. What
is the best estimate of their chance of having another child with achondroplasia?
A. Less than 0.1%
B. 1-2%
C. 25%
D. 50%
E. 100% - ANSWER-A. Less than 0.1%
A couple have a severely affected son with Hunter syndrome, which is diagnosed by
assaying iduronate sulfatase. Two years later, they have a daughter with the same
severe condition and confirmed by enzyme assay. What would be the most important
next step in evaluating this family?
A. Enzymatic carrier testing for both of the parents
B. Determine paternity by HLA typing of the father
C. Take a careful pregnancy history to check for teratogenic exposures
D. Karyotype the daughter
E. Karyotype the parents - ANSWER-D. Karyotype the daughter
(note: Hunter syndrome is X-linked recessive)
A couple who recently had a daughter with a chromosome abnormality comes for
genetic counseling. Their daughter's karyotype is 46,XX,del(3)(p25.3). Both parents are
studied and their karyotypes are normal. The most accurate counseling is that: A. Small
deletions do not usually cause severe birth defects and mental retardation
, B. Although both parents have normal karyotypes, they could still have a small
increased chance of having another child with an unbalanced karyotype due to the
possibility of germ line mosaicism
C. The parental chromosome testing should be repeated since one parent should have
a balanced translocation to explain the deletion in the child
D. The proband's phenotypically normal siblings should be karyotyped to determine if
they are balanced translocation carriers
E. Because the deletion is de novo, the proband is less likely to have birth defects and
mental retardation than if it was inherited se - ANSWER-B. Although both parents have
normal karyotypes, they could still have a small increased chance of having another
child with an unbalanced karyotype due to the possibility of germ line mosaicism
A couple whose first son has isolated hydrocephalus with aqueductal stenosis asks
about their risk to have another affected child. There are no other affected individuals in
the family, and the boy has a normal karyotype. The chance that their next child would
be affected is closest to:
A. 1%
B. 3%
C. 6%
D. 12%
E. 25% - ANSWER-C. 6%
A diagnosis of Hunter syndrome is suspected. What is the most likely pattern of
inheritance?
A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive
D. Mitochondrial
E. X-linked dominant - ANSWER-C. X-linked recessive
A female neonate has profound hypotonia. The only known complication of pregnancy
was polyhydramnios. The mother has a lack of facial expression and weak muscles;
she says she did not have any problems as an infant or child. Which of the following
best explains the difference in presentations in the mother and child?
A. Anticipation
B. Delayed onset
C. Genetic heterogeneity
D. Incomplete penetrance
E. Pleiotropy - ANSWER-A. Anticipation
A full-length cDNA clone will contain sequences corresponding to each of the following
except:
A. Translation start codon
B. Exons
C. Poly-A tail
D. 5' untranslated region
