Chromosomal Abnormalities Test
Questions with Answers
What type of chromosomal abnormality causes Klinefelter Syndrome? - Answer-
Klinefelter Syndrome 47, XXY is a numerical abnormality in which an affected individual
has one extra copy of chromosome X. Affected males have the presence of Barr
bodies.
What are some of the manifestations of Klinefelters Syndrome? - Answer-Klinefelters
Syndrome 47, XXY males are sterile, may present with testicular atrophy and
gynecomastia.
What type of chromosomal abnormality causes Edwards Syndrome? - Answer-Edwards
Syndrome (aka Trisomy 18) is a numerical abnormality in which affected individuals
have an extra copy of chromosome 18.
What are some characteristic presentations of individuals who are affected with
Edwards Syndrome? - Answer-Low-set ears, micrognathia, clenched fists
What type of chromosomal abnormality causes Patau Syndrome? - Answer-Patau
Syndrome (aka Trisomy 13) is a numerical abnormality in which an affected individual
has one extra copy of chromosome 13.
What are some characteristic presentations of individuals who are affected with Patau
Syndrome? - Answer-Mental retardation (holoprosencephaly), cardiac defects,
deafness, cleft-lip and palate, eye defects.
What type of chromosome abnormality causes Turner Syndrome? - Answer-Turner
Syndrome 45, X is a chromosomal abnormality in which an affected individual has one
less copy of an X chromosome.
80% of Turner Syndrome cases occur as a result of what? - Answer-Paternal
(spermatocyte) nondisjunction.
Which monosomy is the only one that is compatible with life? - Answer-Turner
Syndrome 45, X
What are some characteristic presentations of individuals who are affected with Turner
Syndome? - Answer-Short stature, broad chest, short neck, congenital lymphedema of
hands and feet, streak gonads (gonadal dysgenesis), lack of secondary sex
characteristic development of at puberty.
, What is the most common cause of structural abnormalities? What are some different
types? - Answer-Most common cause of structural abnormalities is breakage of a
chromosome during meiosis. This usually occurs during the process of genetic
recombination. There are two types: deletions and microdeletions.
What type of chromosomal abnormality causes Cri du Chat Syndrome? - Answer-
Deletion on the short arm of chromosome 5.
What are some characteristic presentations of individuals who are affected with Cri du
Chat Syndrome? - Answer-Individuals affected have a characteristic cat cry sound due
to malformation of the larynx. These individuals also exhibit growth retardation, mental
retardation, microcephaly and cardiac defects.
What is the most common causer of numerical abnormalities? - Answer-Most common
cause is nondisjunction during meiosis.
If a gamete with one extra chromosome is involved in fertilization, then the resulting
embryo will have a _____. - Answer-trisomy.
If a gamete with one less chromosome is involved in fertilization, then the resulting
embryo will have a _____. - Answer-monosomy.
What type of chromosomal abnormality causes Down Syndrome? - Answer-Down
Syndrome (aka Trisomy 21) is a numerical abnormality in which an affected individual
has an extra copy of chromosome 21.
75% of Down Syndrome cases occur as a result of what? - Answer-Maternal (oocyte)
nondisjunction.
What sort of cardiac defects do individuals affected with Down Syndrome present with?
- Answer-Cardiac defects are found in approximately 40% of cases: usually septal
defects of the PDA (patent ductus arteriosus).
What type of chromosomal abnormality causes 4q syndrome? - Answer-Deletion 4q
syndrome is a deletion on the long arm of chromosome 4.
What are some characteristics of individuals who are affected by a Deletion 4q
Syndrome? - Answer-Affected individuals will exhibit growth retardation, postnatal onset
and will have varying degrees of mental retardation. Affected individuals also have a
cleft palate as well as limb abnormalities.
What is the difference between a deletion and a microdeletion? - Answer-For a deletion,
a large portion (visible) is lost.
For microdeletions, only a small portion (not visible) is lost.
Questions with Answers
What type of chromosomal abnormality causes Klinefelter Syndrome? - Answer-
Klinefelter Syndrome 47, XXY is a numerical abnormality in which an affected individual
has one extra copy of chromosome X. Affected males have the presence of Barr
bodies.
What are some of the manifestations of Klinefelters Syndrome? - Answer-Klinefelters
Syndrome 47, XXY males are sterile, may present with testicular atrophy and
gynecomastia.
What type of chromosomal abnormality causes Edwards Syndrome? - Answer-Edwards
Syndrome (aka Trisomy 18) is a numerical abnormality in which affected individuals
have an extra copy of chromosome 18.
What are some characteristic presentations of individuals who are affected with
Edwards Syndrome? - Answer-Low-set ears, micrognathia, clenched fists
What type of chromosomal abnormality causes Patau Syndrome? - Answer-Patau
Syndrome (aka Trisomy 13) is a numerical abnormality in which an affected individual
has one extra copy of chromosome 13.
What are some characteristic presentations of individuals who are affected with Patau
Syndrome? - Answer-Mental retardation (holoprosencephaly), cardiac defects,
deafness, cleft-lip and palate, eye defects.
What type of chromosome abnormality causes Turner Syndrome? - Answer-Turner
Syndrome 45, X is a chromosomal abnormality in which an affected individual has one
less copy of an X chromosome.
80% of Turner Syndrome cases occur as a result of what? - Answer-Paternal
(spermatocyte) nondisjunction.
Which monosomy is the only one that is compatible with life? - Answer-Turner
Syndrome 45, X
What are some characteristic presentations of individuals who are affected with Turner
Syndome? - Answer-Short stature, broad chest, short neck, congenital lymphedema of
hands and feet, streak gonads (gonadal dysgenesis), lack of secondary sex
characteristic development of at puberty.
, What is the most common cause of structural abnormalities? What are some different
types? - Answer-Most common cause of structural abnormalities is breakage of a
chromosome during meiosis. This usually occurs during the process of genetic
recombination. There are two types: deletions and microdeletions.
What type of chromosomal abnormality causes Cri du Chat Syndrome? - Answer-
Deletion on the short arm of chromosome 5.
What are some characteristic presentations of individuals who are affected with Cri du
Chat Syndrome? - Answer-Individuals affected have a characteristic cat cry sound due
to malformation of the larynx. These individuals also exhibit growth retardation, mental
retardation, microcephaly and cardiac defects.
What is the most common causer of numerical abnormalities? - Answer-Most common
cause is nondisjunction during meiosis.
If a gamete with one extra chromosome is involved in fertilization, then the resulting
embryo will have a _____. - Answer-trisomy.
If a gamete with one less chromosome is involved in fertilization, then the resulting
embryo will have a _____. - Answer-monosomy.
What type of chromosomal abnormality causes Down Syndrome? - Answer-Down
Syndrome (aka Trisomy 21) is a numerical abnormality in which an affected individual
has an extra copy of chromosome 21.
75% of Down Syndrome cases occur as a result of what? - Answer-Maternal (oocyte)
nondisjunction.
What sort of cardiac defects do individuals affected with Down Syndrome present with?
- Answer-Cardiac defects are found in approximately 40% of cases: usually septal
defects of the PDA (patent ductus arteriosus).
What type of chromosomal abnormality causes 4q syndrome? - Answer-Deletion 4q
syndrome is a deletion on the long arm of chromosome 4.
What are some characteristics of individuals who are affected by a Deletion 4q
Syndrome? - Answer-Affected individuals will exhibit growth retardation, postnatal onset
and will have varying degrees of mental retardation. Affected individuals also have a
cleft palate as well as limb abnormalities.
What is the difference between a deletion and a microdeletion? - Answer-For a deletion,
a large portion (visible) is lost.
For microdeletions, only a small portion (not visible) is lost.
