<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by 17 alpha-hydroxylase/17,20-lyase deficiency ? [/INST] 17-hydroxylase/17,20-lyase deficiency accounts for about 1 percent of congenital adrenal hyperplasia cases. It is estimated to occur in 1 in 1 million people worldwide. </s>