I think when you try and answer this question for your sons you have to remember 1 thing:
None of us really know when DMD will take our sons, we just know it is when they still have so much living to do.
So when Mitchell asked if DMD was going to kill him (he was 9) I simply said "yes, but we all have to do die of something."
I then went on to remind him his gran gran died of cancer at 91, his poppy will probably die from diabetes, and his gran will die from MS.
I thought I had gotten away with it by leaving it at that, but then a couple of days later he said "so I'll live to 100 right? and then die of DMD"
We have always had a policy that we would not lie, so I said "No, but only a few people live to 100" He then counted back in decades fom 100 (to my horror) and asked at each one if he'd ever be that old. He stopped at 40 when I said we just don't know about that one (which is true, anything could happen between now and then).
He was very quiet for a while, but then he simply said "well, I guess I've got a lot to do between now and 40" and I realised then honesty about the future was the greatest gift we could ever give him. It has given him the ability to set goals for himself based on realistic time frames. We mourn so many things that we'll never see them do, that sometimes we can forget they have dreams and aspirations too. So giving them the truth from the start ensures their plans for the future are achievable.....
A psychologist told me that they only ask the questions they are ready to hear the answers to, but we as parents must remember to keep the reply age appropriate.
If a 7 year old asks if they are going to die they are not after all the gory details they are just starting to appreciate the concept of mortality. A lot of healthy 7 year olds ask the same question, and for our boys it is not a lie to say "not for a long long time" because lets face it, some-one in their 20's is OLD to a 7 y.o.
The psychologist also said that a lot of the boys have a sense of relief when they finally know the truth. Imagine being trapped in a body that was slowly losing the ability to do all the things you love..... and then sitting there thinking this would be you for the next 60 years.... scary thought isn't it?
Take baby steps answer vaguely at first, and get more specific as your son grows, that way you don't make him grow up sooner than he has to, but you can also ensure that if he hears some-one talking about DMD, and the words terminal or life expectancy come up, he already knows that the condition is terminal, but he won't die for AGES......
Unfortunately the down side to raising awareness is the fact that our boys get exposed to the truth sooner, but if you are open and honest, this can be a period of immense growth, with only a hint of sadness.......
Keep your chin up, and know it will all be OK at the end of the day......
I don't have much advice to offer, but I wish Tower wasn't so far from Shakopee because I'd drive up and give you both a big hug! My son is also 7 and he doesn't know the whole mortalilty issues with DMD. But he does understand that everyone has their time and that God had a plan for everyone. If he were to ask me I would tell him the truth that DMD could cause him to have an earlier death, but I will not volunteer that information to him at this age.
In your post you said your son doesn't fit the general DMD spectrum. I wondered what exactly your thoughts were on what the general dmd spectrum is? I assume you are talking about progression, right?