<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by Waardenburg syndrome ? [/INST] Waardenburg syndrome affects an estimated 1 in 40,000 people. It accounts for 2 to 5 percent of all cases of congenital hearing loss. Types I and II are the most common forms of Waardenburg syndrome, while types III and IV are rare. </s>