new_n_lost
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Tissue from a spontaneous abortion is submitted to the laboratory, where an astute pathologist notes the presence of mature fetal tissue that contains Barr bodies. The fetus may have had which of the following genotypes?
A. Classic Turner syndrome (45, X)
B. Edward's syndrome (47, XY+1)
C. Klinefelter's syndrome (47, XXY)
D. Normal male (46, XY)
E. XYY syndrome (47, XYY)
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| GoodGirl
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Hey, I had to use the dictionary for the word '' astute''  .
With my poor knowledge of Genetics, just a blind shot : C
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| jean robert
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c
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| drpswathi
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B
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| acintya
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C?
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| new_n_lost
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GoodGirl wrote:Hey, I had to use the dictionary for the word '' astute'' . With my poor knowledge of Genetics, just a blind shot : C 
Lol your blind shot works better than mine.
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| new_n_lost
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The correct answer is C.
The Barr body, or X chromatin body, is an inactivated X chromosome seen as a small, perinuclear, dark-staining dot in somatic cells with two or more X chromosomes. Barr bodies are seen in any individual born with at least two X chromosomes, including normal females. (47, XXY), the classic karyotype of Klinefelter's syndrome, is defined as male hypogonadism due to the presence of a Y chromosome and two or more X's. As in normal females, one of the X chromosomes becomes a Barr body in Klinefelter's syndrome.
Classic Turner syndrome females (choice A) and genotypically normal males (choice D) have only one X chromosome. Thus, no X chromosome is inactivated, and somatic cells do not show any Barr bodies.
(47, XY+1)is the karyotype of an Edward's syndrome (choice B) fetus. Although this trisomic phenotype is associated with a characteristic syndrome of physical abnormalities, there is no programmed inactivation of the extra chromosome 18. Thus, no Barr body is produced.
XYY syndrome (choice E) is not associated with inactivation of any X chromosomes, so Barr bodies are not present. Like a trisomy involving any of the non-sex-linked chromosomes, the duplicated chromosome is expressed in its entirety.
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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