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Hi, I will try to explain this the best I can. In BMD, most times the reading frames are" in-frame "as with your son. A deletion of exon 3 causing a IN-Frame Mutation in the dystrophin gene. 90% of the time this means Becker Muscular dystrophy in about 10% of the time it means the more severe Duchenne Muscular Dystrophy. In Becker when the reading frame remains intact it still makes sense and thus some dystrophin is produced causing the less severe Becker. Please look at the below example. This sentence is the Dystrophin Gene.
(A)The big fat cat ate the little mouse. (all letters are in the gene thus making full lenght dystrophin) Now in Beckers, a word is missing which shortens the gene but still makes sense.
(B) The fat cat ate the little mouse. (becker muscular dystrophy) In-Frame Deletion, still makes sense & some dystrophin is produced.
(C) The ate the little mouse. (Duchenne Muscular Dystrophy) This would be example of OUT-of-Frame Deletion. The sentence does not make sense so no or very little dystrophin is produced thus the more severe form of the disease.
This is all very confusing cause sometimes you can have out-of-frame deletion and have very mild becker and of course the other way round. You can have In-frame and still have very little dystrophin produced causing Duchenne. I can't explain that one to you. I don't think the researchers can't even answer that one.
I hope this makes some sense to you and I haven't confused you more. |
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Roxanne Mom to Nicholas (10) with BMD |
