<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by osteogenesis imperfecta ? [/INST] This condition affects an estimated 6 to 7 per 100,000 people worldwide. Types I and IV are the most common forms of osteogenesis imperfecta, affecting 4 to 5 per 100,000 people. </s>