Because the condition has not long been recognised, the group of affected boys has not been followed for sufficiently long to know much about life expectation. Some adults are healthy into their thirties. We do not have post-mortem information to know the cause of death in older cases.
A number of children perish under the age of five years. Pneumonia is frequently the cause. Repeated chest infections are possibly related to episodes of vomiting and food going down the 'wrong way' into the lungs.