I have heard it said that there is a surprising amount of heart disease and other health complications in Arab families. This is largely due to inbreeding.
Another possibility that is no doubt the object of rumor in the region as we speak, is palace intrigue. He was, after all, the heir to the kingdom that sits atop a good chunk of the world’s wealth.
Nix no. 2-he was the eldest son but NOT the heir apparent-glad I never got into royal genealogy!