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  #1  
Old 10-07-2011
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Question Barr bodies in fetal tissue!

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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Old 10-07-2011
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I guess knielfelters syndrome
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Old 10-07-2011
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i don't know i ll try klinefilter syndrom too
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Old 10-07-2011
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A.turners syndrome
Akua
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Old 10-07-2011
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Default C. Klinefelters

If the answer is Klinefelters, is that two Barr bodies per somatic cell?
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Old 10-07-2011
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Default The rule of Barr bodies

The rule is like that ::

Barr bodies number = number of X chromosomes - 1

So if we had Klinefelter's syndrome (47, XXY)

Then number of Barr bodies = 2 -1 = 1 Barr body
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Default A. Classic Turner syndrome (45, X

Quote:
Originally Posted by l2sweedan View Post
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)
A. Classic Turner syndrome (45, X
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Quote:
Originally Posted by l2sweedan View Post
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)
classic turner is a monosomy consistent with life it would be if it had been explained by genetic mosaicism so i guess i pick kleinfelter's
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Old 10-07-2011
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Klinefelter in my view...
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Old 10-07-2011
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are we there?would u plz give the answer:sorry:
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Old 10-07-2011
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Barr body is an inactivated X chromosome.
Permanent inactivation of one of the X chromosomes occurs only in normal female somatic cells which contain two X chromosomes (XX).
The only option that entails two X chromosomes is C Klinefelter's syndrome (47, XXY).
The mechanism of inactivation of one X chromosome occurs in none of the other options, apparently because there is one X chromosome.
So i will go with C.

This is how i get it...
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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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