Kindregan suffered from ataxia-telangiectasia, or A-T, a genetic, degenerative multi-system disease which causes severe disability.
Most children with A-T are confined to a wheelchair by the age of 10 and do not survive their teens, reported Access Hollywood.
Affleck first met a then-10-year-old Kindregan on the set of the actor's film, "Forces of Nature", in 1998. Affleck noticed Kindegran as he was watching them film on location, and invited him over to chat.
As part of the Make-A-Wish programme, Kindregan attended the Hollywood premiere of "Forces of Nature", and the two have kept in constant contact ever since.