amniotic fluid kayotype conflicting result

[axel.lenn]

Hello,

I am facing a situation with a pregnancy with single female fetus where amniotic karyotype revealed a 45XX result in one culture and 46XY in the other. The father is 46XY, the mother is 46XX. There was no comment on the result but an indication to repeat the amniocentesis - this is not an ordinary procedure to indicate easily, especially when it comes to repeat it. To me, this result really makes no sense, the discrepancy between the two cultures seems to indicate different origins.

What is your opinion on this result?

Thank you in advance!

[Endy0816]

Chimera?

[StringJunky]

There is a Wiki on 45,X/46,XY.

 

 

45,X/46,XY mosaicism, also known as X0/XY mosaicism and Mixed gonadal dysgenesis,^[1] is a rare disorder of sex development in humans associated with sex chromosome aneuploidy and mosaicism of the Y chromosome. This is called a mosaic karyotype because, like tiles in mosaic floors or walls, there is more than one type of cell.

 

The clinical manifestations are highly variable, ranging from partial virilisation and ambiguous genitalia at birth, to patients with a completely male or female gonads. Most individuals with this karyotype have apparently normal male genitalia, and a minority with female genitalia, with a significant number of individuals showing genital abnormalities or intersex characteristics.^[2] A significantly higher than normal number of other developmental abnormalities are also found in individuals with X0/XY mosaicism.^[2] Psychomotor development is normal.

 

https://en.wikipedia.org/wiki/45,X/46,XY_mosaicism

Edited March 25, 2016 by StringJunky

[axel.lenn]

Thank you for your ideas, mosaicism or chimera. However, the result is 45XX in one culture, and 46XY in the other culture. It was the same amniotic fluid supposedly, and I think if such a rare case of masicism would occur, one would expect to find a mixture of cells in both cultures. In this case,there are completely different cell populations in different cultures which makes me think that the second culture is actually not from the same sample.

amniotic 1.bmp

amniotic 2.bmp

[Xalatan]

This is interesting. I'm not a medical geneticist and this should not be considered expert advice. My understanding of Chimera and mosaicism is like you pointed out, they should logically result in both amniotic karyotypes having a mixture of 45XX and 46XY. As you reasoned, since the fetus is female, 45XX with monosomy 14 may be the genotype of the fetus.

 

However, I'm reading wiki and it says "Fetuses with monosomy 14 are not viable.^[1] Only mosaic cases exist and these usually present with severe symptoms such asintellectual disability, ocular colobomata, microcephaly, and seizures." Which makes me wonder about the validity of the 45XX karyotype also.

 

If the fetus is indeed 45XX with monosomy 14, then according to the above, at 14-16 weeks the fetus may not be viable. Or, if it is indeed a mosaic, then the above features may be present. What I may not expect is if the female fetus is normal for its embryonic stage.

 

​Also, conditions like ring chromosome 14 should also be a type of mosaicism, which doesn't fit the pattern of amniotic cultures.

Edited March 25, 2016 by Xalatan