amkjud,
MDS is already rare, and pediatric MDS makes your son's case even more unusual. One bit of good news is the number of treatment facilities with expertise in MDS in the New York area. I suggest that you contact some or all of these
New York treatment centers and those in neighboring states, ask if they've treated pediatric MDS cases, and get to at least one for a second opinion.
If you can't find a pediatric hematologist with MDS expertise then you might do well to have a team of doctors with both a pediatric hematologist and an expert on adult MDS.
The factors that go into decisions about
treatment of MDS are likely to be different for kids compared to the typical newly diagnosed MDS patients in their 60s or 70s.
Seniors with high risk MDS are often given anti-angiogenic or demethylating agents, but I suspect that if the diagnosis is confirmed then a transplant from a sibling or an unrelated matched donor would be more heavily considered for your son. Do you have other children? If so, I encourage you to get them HLA tested as potential transplant matches, if the doctors agree.
Seniors with low risk MDS may receive only supportive care with transfusions, especially those of the highest age and with other health problems. With a 7-year-old I would expect doctors to recommend more aggressive measures. After all, he's got his whole life ahead of him.