Deletion
Unsure if anyone can help with my query, but my nephew was diagnosed with Duchenne 2 years ago and he has a deletion of 8-21. His biopsy shows his phenotype is duchenne but his deletion shows he should have mild BMD. Hospital say he doesnt have another deletion elsewhere. Has anyone heard of this before, as we are still trying to understand why he would have DMD and not BMD. Could the hospital have missed anything??
Replies to This Discussion
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Permalink Reply by Lori Ware on
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My first question is where was the DNA sent? Was the entire gene sequenced?
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Permalink Reply by Tulika on
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Lori,
Looks like there is more to the reports which tell us that a certain exon is deleted.
Please share information, on gene sequecing and how it can give more meaning ful insight in the exon deletion report.
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Permalink Reply by Eliane Khoury on
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Lori, not sure. We found this out because the Hospital sent some tissue to Perth to grow and the scientist said that his deletion was Mild BMD, unless he has another deletion not detected. The hospital replied to him saying his muscle biopsy was tested three times and there isnt another deletion. All this was done at Westmead Childrens hospital in Sydney.
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Lori, not sure. We found this out because the Hospital sent some tissue to Perth to grow and the scientist said that his deletion was Mild BMD, unless he has another deletion not detected. The hospital replied to him saying his muscle biopsy was tested three times and there isnt another deletion. All this was done at Westmead Childrens hospital in Sydney.
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ok, i am not the scientist on the board, so I will ask for help (that and the fact that it is 1AM in Louisiana and i am up waiting on the storm, high and dry in North LA). Gene sequencing is when the ENTIRE gene is tested. Normally, well, in the recent past, most labs would test a gene until they find a mutation and leave it at that. Gene sequencing tests the entire gene, not just until the first mutation is found. I know it is now done in several US locations (Utah and Emory), but am not sure internationally. As for the biopsy showing deletions...I am not sure, as my son never had a biopsy, but I thought a biopsy only showed if dystrophin is produced or not. with no dystrophin you have DMD, if there is some you have BMD. Now, I could be wrong on that and it may be possible to do DNA from biopsy. I would ask for help there.
Hope this helps some..
Lori
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Deletion testing can predict whether deletion is likely to be in frame or not. However, a more important issue is what the biopsy showed as far as damage and, most importantly, whether dystrophin is being produced. In other words, the most predictive test would be dystophin staining tests performed on the muscle from the biopsy. Was this done? Also, a mild becker would likely result in a cpk much lower than the often 20,000 to 30,000 amount found in young duchenne patients. A cpk of 1 to 2000 in a very young patient would point towards a more mild form of dystrophy. cpk in the 20,000 to 30,000 range (sometimes higher-the amount of course varies from day to day) would point to duchenne profile. Finally, even if the deleted exons should result in an inframe deletion (with truncated dystrophon), there are also so-called splice site problems that can result in no dystrophin being produced. Bottom line, the amount of dystrophin is usually the critical factor in severity. The length or quality of the dystrophin can also make a difference. In other words, a normal amount of non-functional dystrophin can result in duchenne prognosis, even if technically Becker.
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I havent had a chance to speak to my brother about gene sequencing. My nephews cpk is in the range between 20,000 and 30,000. He does produce only 5% dystrophin but we were told also not in the right places.. I am sure they did the dystrophin staining. You mentioned splice site problems. What does that mean?? They say Exon skipping might not help him as his deletion is in-frame and were were hoping it would as that is probably the closest thing other than PTC that might eventuate. Just trying to find answers and look for a glimmer of hope as I know we are looking for that hope.
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I havent had a chance to speak to my brother about gene sequencing. My nephews cpk is in the range between 20,000 and 30,000. He does produce only 5% dystrophin but we were told also not in the right places.. I am sure they did the dystrophin staining. You mentioned splice site problems. What does that mean?? They say Exon skipping might not help him as his deletion is in-frame and were were hoping it would as that is probably the closest thing other than PTC that might eventuate. Just trying to find answers and look for a glimmer of hope as I know we are looking for that hope.
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Trials for exon skipping are underway but it will be a while before they move much farther than 51. Look into Utrophin. it will work on all boys and is natural to our bodies. trials for it will begin in 09..
There are 2 researchers working on Utrophin, Kay Davies of the UK and Prosensa. Kay Davies is leading the way. there is also some good stuff coming for cincinnati childrens next year. Look at the conference summary for info about all upcoming treatments.
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I have read about Utrophin. It does look promising and I want to believe that all these boys will have a treatment soon but when I read at how long it takes to get the drugs onto the market its puts a damper on it all.
All we can do is pray and fundraise to keep the trials going.
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I have read about Utrophin. It does look promising and I want to believe that all these boys will have a treatment soon but when I read at how long it takes to get the drugs onto the market its puts a damper on it all.
All we can do is pray and fundraise to keep the trials going.
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Hi,
Need someone to clarify my understanding. I have listed these below, can someone comment, if any of these is worng.
1. When doing the tests, first all exons are tested for deletion or duplication. If deletion or duplication is found then it is confirmed by another genetic test. Only after these two tests is the first report given on exon deletion or duplication.
2. If no deletion or duplication is found then gene sequencing is done to find out things like point mutation.
3. Only if genetic tests do not confirm and co-rellate to observations, then we need to go for a biopsy to actually look at the muscles under a microscope. Biopsy will also help if the deletion is in frame and length of the dystophine needs to be determined.
4. If genetic tests have confirmed a out of frame deletion or duplication then there is no need of a biopsy since there will be no dystrophine.
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