18 Questions
What is the approximate incidence of Klinefelter syndrome in males?
1 in 500
What is the most common causative event of Klinefelter syndrome?
Nondisjunction of the XX homologues
What is the characteristic feature of Turner syndrome?
Short stature and absence of ovaries
What is the percentage of affected women who are monosomic for the X and chromatin body negative?
55%
What is the cause of breaks in chromosomes that can lead to structural abnormalities?
Radiation and environmental factors
What is the fate of most fetuses with Turner syndrome?
They are spontaneously aborted
What is the percentage of conceptuses that have major chromosomal abnormalities?
25%
What is the term for the phenomenon where some cells of an embryo have a normal number of chromosomes and others have an abnormal number?
Mosaicism
During meiosis, what is the result of nondisjunction in one cell?
One cell with 24 chromosomes and the other with 22 chromosomes
What is the term for a chromosome number that is not an exact multiple of n?
Aneuploidy
What is the result of a translocation where no critical material is lost?
Balanced translocation
At what age do the frequency of nondisjunction in women particularly increase?
35 years
What is the result of partial deletion of the short arm of chromosome 5?
Cri-du-chat syndrome
What percentage of human malformations are estimated to be caused by single gene mutations?
8%
What is the term for a mutation that requires two abnormal alleles to produce an abnormality?
Recessive
What is the result of a microdeletion of the long arm of chromosome 15?
Microdeletion of long arm of chromosome 15 (15q11-15q13)
What type of mutation can result in inborn errors of metabolism?
Gene mutation
What is the term for a mutation that can produce an abnormality in a single dose?
Dominant
Test your understanding of chromosomal abnormalities, including numerical and structural defects, and their relationship to birth defects and spontaneous abortions. Learn about euploid, aneuploid, trisomy, and monosomy, and how they originate during mitosis or meiosis.
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