<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by epidermolysis bullosa simplex ? [/INST] The exact prevalence of epidermolysis bullosa simplex is unknown, but this condition is estimated to affect 1 in 30,000 to 50,000 people. The localized type is the most common form of the condition. </s>