Operational definition of cystic fibrosis. I.

Recently, one of us suggested a new hypothesis concerning the 'basic defect' 
of cystic fibrosis. The purpose of the present paper is to 
review this model and to critically discuss its eventual diagnostic applications. 
With extensive studies, we collected experimental data which contribute five major 
arguments in favour of the proposition that CF may be an 
enzyme recognition site mutant. With fibroblast cultures the three genotypes can 
be separated in the following way: CF homozygote, leaky for alkaline 
phosphatase (A1P) and lysosomal hydrolases/A1P is Tamm-Horsfall glycoprotein (THP) inducible; CF 
heterozygote, leaky for A1P and lysosomal hydrolases/A1P is not THP inducible; 
normal control, not leaky for A1P and lysosomal enzymes/A1P is not 
THP inducible. With the exception of a second double-blind study, the 
THP induction as well as the leakage analysis seem to be 
statistically unequivocal: they strongly support our hypothesis concerning the basic defect 
in CF. 