A clinical perspective of cystic fibrosis and new genetic findings: relationship of CFTR mutations to genotype-phenotype manifestations.

The present report describes several aspects of the relationship of mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene to phenotype expression of the disease including several clinical vignettes from the authors' experience. The genotype-phenotype relationships in CF are complex, and are affected by many factors, including pollution, smoking, bacterial infection, malnutrition, and certain therapeutic agents. The number of CFTR mutations is growing continuously and rapidly, and more than 1,000 mutations have been discovered so far. From a genetic point of view, the deltaF508 mutation is not only the most frequently encountered but also the most severe genetic lesion for homozygotes. The great clinical variability observed in patients with CF, particularly the severity of lung disease, involvement of the pancreas, and male infertility, are beginning to be better understood through the knowledge, although incomplete, of CFTR mutations and their phenotype expressions. This knowledge has had very significant research and clinical applications in all dimensions of the CF problem. It has not only contributed to the enhancement of better diagnosis and clinical management, but it also has opened new and unanticipated lines of investigation and research.