SuperHeroes for Silas

Here is Silas' story told by his parents:

We are an Active Duty Navy Family. Harvey serves on a Submarine and is gone around 6 months out of every year. We have two beautiful kids, Silas(3) and Violet(2). We are thrilled to be expecting our third child in Aug 2014, another boy. We found out in Sept 2013 that Silas had a duplication on his 6th chromosome. He is the only person on record to date with this exact duplication. We were told they were unsure if this was causing the issues Silas was having at the time and while they could not say for certain, they had no reason to believe he would get worse. Unfortunately, they were wrong. In Dec 2013 we found out we were expecting our 3rd child. Right about the same time Silas began to show signs of decline. We have since found out that he has no response from any of the sensory nerves that were tested on the NCV and that he had no response from either ear on the ABR. Which means he has Auditory Neuropathy. As a result of these tests and the other areas Silas is is showing decline in have led them to believe Silas has one of two rare genetic disorders. One that called Infantile Onset SpinoCerbellar Ataxia, there are roughly 50 documented cases of worldwide in which Harvey and I would have to be recessive carriers of and could be a risk to all of our kids. The other called Charcot-Marie-Tooth neuropathy type 5 would have been passed from me to Silas and only effects males while females are carriers. Since we are soon having another boy, it would be nice to know what to expect for Sawyer. Both have the potential to drastically shorten his life expectancy as well as take away his hearing and vision completely while he will continue to lose mobility.. Because it is so rare, the testing is considered experimental and our insurance will not cover it. His doctors have exhausted the appeals process to insurance and we have contacted every major hospital that we can find only to be denied again and again. Most of them do not do the testing themselves, they only treat after diagnosis or they will not do testing without insurance paying for it. So, we sit here and watch our child decline. Cognitively he is untouched. So he is beginning to see that he is not like other kids his age. He is asking my questions like why other kids wont play with him or wait for him at the play ground. He sees that he cannot keep up with his younger sister. And he gets frustrated when he cannot hear us. How can I explain these things in terms a three year old will understand when I do not even have the answers to give him?