Variability in cystic fibrosis [letter].

All of us who care for patients with cystic fibrosis (CF) are 
well aware of the varying degrees of clinical involvement they have. 
It has long been known that whereas the most patients have 
pulmonary involvement of one degree or another, approximately 15% to 20% 
of patients will not have any pancreatic involvement. In the 80% 
to 85% of patients with pancreatic involvement, the degree of involvement 
can vary greatly. If we can accept the concept of clinical 
heterogeneity for the pulmonary and gastrointestinal systems, there is no reason 
why we should doubt the existence of clinical variability for the 
other major organ system affected by this disease, the sweat glands. 
