DNA molecular biology in the diagnosis of pulmonary disease.

DNA molecular biology is becoming increasingly important in clinical medicine. It has provided a new method to diagnose an inherited pulmonary disease in which the biochemical defect has been defined. Alpha-1-antitrypsin deficiency can now be diagnosed by direct analysis for the disease gene. In cystic fibrosis, another inherited pulmonary disease, the biochemical defect has not yet been defined. However, the search has been narrowed. The cystic fibrosis genetic defect has recently been localized to the long arm of chromosome 7. Because polymorphic DNA markers (RFLPs) are available for this region of chromosome 7, it is now often possible, using linkage analysis, to trace the inheritance of the cystic fibrosis gene(s) in families known to have cystic fibrosis. When the cystic fibrosis genetic defect is defined, it will then be possible to look directly for the disease gene. Finally, the greatest impact in clinical medicine may well be the development of rapid DNA hybridization techniques to diagnose infectious diseases that currently take days to weeks to diagnose.