<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by hemophilia ? [/INST] The two major forms of hemophilia occur much more commonly in males than in females. Hemophilia A is the most common type of the condition; 1 in 4,000 to 1 in 5,000 males worldwide are born with this disorder. Hemophilia B occurs in approximately 1 in 20,000 newborn males worldwide. </s>