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Hey there not sure if anyone knows much about Gonadal Mosaic but that's what the geneticist told me I have meaning that some of my eggs have the mutation and some do not as my daughter has the deletion and is a carrier and my son has DMD he is exon deletion of 3-11. Does anyone know anything about this that can help me understand it and what would i see in my daughter (17) if she is a manifesting carrier. Thanks in advance for any help or information.

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Hello Betty-Anne,

Thank you for your question.  You are correct that gonadal mosaicism means that some of the woman's egg cells have the mutation and some do not.  Woman who have gonadal mosaicism usually test negative on a blood DNA test, because the mutation is not in their blood cells, only in some of their egg cells.  These women don't know they have gonadal mosaicism until they have a second affected child, after being told they were not a carrier based on blood testing.  Have you had your blood drawn for carrier testing?  If you have and if you have the same deletion as your son, then you would not have gonadal mosaicism.  I realize this may be confusing, so feel free to call me if you have any questions (201-937-1408). 

Regarding your daughter, if her mutation has been confirmed, she should see a cardiologist for her baseline exam, if she hasn't already.  In addition to cardiac signs, manifesting carriers can also have varying degrees of muscle weakness.  If you are concerned about your daughter's strength, you should have her evaluted by a neurologist.

Please let me know if you have any questions!

I did have my blood tested and I am negative I guess they determined the gonadal mosaicism  as my daughter and my son both have the same deletion.  We are still waiting for an appointment with the cardiologist for her. I am still trying to read information and learn how best to help him and what to expect. He had his heel cord surgery in February and is doing really well since with no toe walking but he still falls a fair bit and gets tired easily. So not sure what other questions I should ask but maybe I can call sometime to get information and a friendly voice. Thanks

I thought that if you were to have gonadal mosaicism all your eggs would be affected not just some of them.  I have a 5 year old son with an exon deletion of 8-12.  I also have a 3 year old daughter.  If i donot have the carrier status and niether does my daughter I take it as a spontaneous mutation not gonadal mosaicism...right???

I was told by our geneticists that 'spontaneous mutation' simply meant that there was no family history of that mutation in the family and that no-one else in the family is affected.

Gonadal mosaicism is a spontaneous mutation. If you were found to be a carrier then it would be a familial mutation. If the mutation occurs in the ovum (egg cell) that produces that child, then DMD will result. Mosaic means that some of the cells express the gene and some do not. So all of the eggs would not be affected. 
 
Kathleen Devine said:

I thought that if you were to have gonadal mosaicism all your eggs would be affected not just some of them.  I have a 5 year old son with an exon deletion of 8-12.  I also have a 3 year old daughter.  If i donot have the carrier status and niether does my daughter I take it as a spontaneous mutation not gonadal mosaicism...right???

Hi Kathleen,

I apologize for my delay to your question. If a woman is a gonadal mosaic, then only some of her eggs would be affected, not all of them. Mosaicism means a mixture of cell types, some some would have the DMD mutation and some would not. If you have been tested and you are not a carrier, and your daughter has been tested and she is not a carrier, then it is very likely that the DMD mutation started as a spontaneous or "de novo" (new) mutation in your son. This means that he is the first in the family affected and the mutation could only be passed on by him.

Please let me know if you have any other questions!
Best,
Ann

Ann,

Maybe this is just me but I have concerns with you answer. I feel if someone read your post they might take away from it that the chances of having another child with the mutation was a remote possibility. While it is unlikely that it would be passed down to another child that Kathleen had it would not be unheard of for that child to have or carry  dmd. Even with her and her daughter not being genetic carriers she could still pass the mutation on if it is in any other eggs that she carries. 
 
Ann Martin said:

Hi Kathleen,

I apologize for my delay to your question. If a woman is a gonadal mosaic, then only some of her eggs would be affected, not all of them. Mosaicism means a mixture of cell types, some some would have the DMD mutation and some would not. If you have been tested and you are not a carrier, and your daughter has been tested and she is not a carrier, then it is very likely that the DMD mutation started as a spontaneous or "de novo" (new) mutation in your son. This means that he is the first in the family affected and the mutation could only be passed on by him.

Please let me know if you have any other questions!
Best,
Ann

Hi Janine,

I apologize for the confusion.  It is true that there is still a very small chance that a woman can have a second affected son even if she tested negative for carrier status on blood testing.  The risk has been quoted as high as 15% in the medical literature, but most clinicians agree that this number is too high in reality because we just don't see it happen this often.  However, it is always recommeded that all woman who have a family history of Duchenne be offered prenatal diagnosis regardless of their carrier status, because gonadal mosaicism is a possibility. 

Let me know if you have any other questions.

Thanks,

Ann

Actually, there is no data proving this. There are a couple of non-carrier moms here having multiple rounds of IVF/PGD. One had 75% of her eggs carrying the mutation, the other 15% of her eggs. Hence the probability to have another son with Duchenne varies and should never be quoted as low. 

Ann Martin said:

Hi Janine,

I apologize for the confusion.  It is true that there is still a very small chance that a woman can have a second affected son even if she tested negative for carrier status on blood testing.  The risk has been quoted as high as 15% in the medical literature, but most clinicians agree that this number is too high in reality because we just don't see it happen this often.  However, it is always recommeded that all woman who have a family history of Duchenne be offered prenatal diagnosis regardless of their carrier status, because gonadal mosaicism is a possibility. 

Let me know if you have any other questions.

Thanks,

Ann

what is IVF/PGD??

IVF/PGD is where eggs are fertilised outside of the body, then the resultant embryos are tested at 3 day of development (when still a small number of cells) for the genetic mutation that caused DMD in your family. Only healthy embryos are then transferred back into the body to hopefully result in a pregnancy.

PGD (pre-implantation diagnosis) can also be used to screen for a whole host of other inherited conditions.

I had PGD and now have THE most beautiful 2 y/o boy - unaffected by DMD.

I hope this helps.

We went and saw a geneticist who told us of our chances were in having another child with DMD. As we werent a carrier the chance of it happening again was listed at about 10% through gonadal mosaiciscm. If we went PGD/IVF  it would reduce the risk to 5%.

We decided the issue with IVF/PGD werent worth the reduction by 5% so we took or chances and went for it! We did have a CVS at 12 weeks, and we had a girl after 3 boys!

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