<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by hereditary angioedema ? [/INST] Hereditary angioedema is estimated to affect 1 in 50,000 people. Type I is the most common, accounting for 85 percent of cases. Type II occurs in 15 percent of cases, and type III is very rare. </s>