Step I Hard question about turner

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stronghold

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If you have a 17 y/o female patient with short stature and webbed neck. She presents without secondary sexual characteristics. Normal uterus and vagina. 46XY. What is the cause?
mitotic nondisjunction
x to y translocation
y to x translocation
meitotic nondisjunction

I guess the answer has to deal with 46XY in stem
 
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My logic: Since the karyotype is perfect, it can't be nondisjunction. The only thing separating a normal 46XY from this 46XY Turner's patient is the Y chromosome genetic info in a normal male - therefore, it must be a Y to X translocation (loss of Y material).

Never really heard of this particular case before though, so weigh my response with others'.
 
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Its mitotic non-disjunction. This isn't really a difficult question, I just think you guys are missing the point a little and overthinking it.
The non-disjunction here occurs AFTER meiosis, in the early stages of post-fertilization mitosis... so therefore what you get (for example purposes) is 50% cells with 46XY and 50% cells with 45XO. Then, therefore, depending on which cell you sample and analyse, you'll either get a 46XY karyotype result OR a 45XO karyotype result. This is mosaicism.
 
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Doctosanthewan said:
Its mitotic non-disjunction. This isn't really a difficult question, I just think you guys are missing the point a little and overthinking it.
The non-disjunction here occurs AFTER meiosis, in the early stages of post-fertilization mitosis... so therefore what you get (for example purposes) is 50% cells with 46XY and 50% cells with 45XO. Then, therefore, depending on which cell you sample and analyse, you'll either get a 46XY karyotype result OR a 45XO karyotype result. This is mosaicism.
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Uh, I think that's what I already said.
 
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In crossing over some genetic material (SRY) was lost, or a germline point mutation or deletion occurred in this gene. She has a Y gene but it is not functioning properly. We were presented this case in my biochemistry course.
 
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ClinPathDO said:
In crossing over some genetic material (SRY) was lost, or a germline point mutation or deletion occurred in this gene. She has a Y gene but it is not functioning properly. We were presented this case in my biochemistry course.
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Or or or. Could you be more specific? What case were you presented and what exactly was the conclusion?
 
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ClinPathDO said:
In crossing over some genetic material (SRY) was lost, or a germline point mutation or deletion occurred in this gene. She has a Y gene but it is not functioning properly. We were presented this case in my biochemistry course.
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Now you're talking about sex reversal (XY Female = SRY region deletion). 46XY/45XO Mosaics can still have turner syndrome with a fully functioning Y chromosome. The phenotype of any mosaic depends on the proportion of cells with each genotype.

In other words, a 46XY [1]/45XO [19] will be more phenotypically Turner's than a 46XY[19]/45XO[1]. However, that's not relevant to the OP.

Edit: Does the OP have the answer? My guess is X to Y translocation because a Y to X translocation is the definition of an XX Male. Not an XY female.
 
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I agree you can have Turner with a functional Y chromosome in the mosaic form, but if you do a karyotype on peripheral blood you should pick up both chromosomal variations. If you have a translocation you will have some Y genetic material left but not enough. The question might be missing some information. Did they just biopsy a certain tissue? Was 46, XY an early embryologic karyotype or present? Mosaic is the most likely cause but I think we lost some information in translation of the question. Mitotic nondisjunction would be the cause of mosaic. I could just be overthinking this though.
 
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ClinPathDO said:
I agree you can have Turner with a functional Y chromosome in the mosaic form, but if you do a karyotype on peripheral blood you should pick up both chromosomal variations. If you have a translocation you will have some Y genetic material left but not enough. The question might be missing some information. Did they just biopsy a certain tissue? Was 46, XY an early embryologic karyotype or present? Mosaic is the most likely cause but I think we lost some information in translation of the question. Mitotic nondisjunction would be the cause of mosaic. I could just be overthinking this though.
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Yeah I agree that it seems like some information is missing
 
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