I had not heard this news, so Googled and found this:
http://sports.espn.go.com/nba/news/story?id=5305868

He died from kidney disease, and a painful skin condition that may have been caused by kidney medication he took when in Africa. He was from Sudan, and was helping humanitarian efforts there, and building a school as well.

Rest in peace, sir, you were a giant both on the court and in heart. May your legacy help thousands to better lives.