Hard question about turner

[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

 

[Anastomoses]

Turner 45X/46XY is a mosaic form. Mosaicism occurs in mitotic nondisjunction.

 

[stronghold]

Turner 45X/46XY is a mosaic form. Mosaicism occurs in mitotic nondisjunction.

Thanks. But I know that Mosaicism is 45X/46XX. However, the stem is 46XY. Is it still the same answer?

 

[Apoplexy__]

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'.

 

[Anastomoses]

Thanks. But I know that Mosaicism is 45X/46XX. However, the stem is 46XY. Is it still the same answer?

There are many mosaic forms - not just 46XX. 46XY must be 45X/46XY, isn't it?

 

[Doctosanthewan]

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.

 

[Anastomoses]

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.

Uh, I think that's what I already said.

 

[Doctosanthewan]

Uh, I think that's what I already said.

Yes you did, but I think to someone who doesn't already understand the subject it can be a little tricky, so I went and just explained it from the top for the benefit of the OP. My comment was not directed at you.

 

[stronghold]

Thank you guys. Is it mitotic non-disjunction, even the stem states that she has vagina and uterus?!

 

[ClinPathDO]

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.

 

[Anastomoses]

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.

Or or or. Could you be more specific? What case were you presented and what exactly was the conclusion?

 

[ulikedaggers]

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.

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.

 

[ClinPathDO]

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.

 

[ulikedaggers]

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.

Yeah I agree that it seems like some information is missing