<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by maple syrup urine disease ? [/INST] Maple syrup urine disease affects an estimated 1 in 185,000 infants worldwide. The disorder occurs much more frequently in the Old Order Mennonite population, with an estimated incidence of about 1 in 380 newborns. </s>