As in the title says, Baldwin IV or the Leper King, became King of Jerusalem at its highest extent in the 1180's, he dies from the disease and his successor Baldwin V also has leprosy and dies, leaving Guy de Lusignian to ascend, who, as we know, Fucks up at Hattin, and sends the Kingdom FUBAR.
He died at a early age (24)
So what would happen if Baldwin didn't have Leprosy?