first of im so sorry for all this happening... but i do not know a lot about
it but there are three websites i know of:
http://www.nsgc.org/ which is the national society of genetic counselers, which has links on there page to find a genetic counseler, which could do the tests.... looks lik this site would be ur best bet, and give u some good info!
You could also try the national cancer institue, im not sure if that would help ur specific case, but it might be worth a try? http://www.cancer.gov
Or also the surgeon general's site, again not sure how much help but worth a try! https://familyhistory.hhs.gov
Hope some of this is helpful... and i hope ur son gets all staightened out, and he and all ur kids have no problems ever! i know, sounds cliched and waaayyyy optimistic, but hey! i know ur worried, so ill be positive and optimistic for u! haha- i know how hard it is to be when its you or someone close to you! anyway best of luck!
"In God's hands, in God's time."
"The scourge of life, and death's extreme disgrace, the smoke of hell, that monster called Pain."