The year 1993 marks the 40th anniversary of the publication of the two short, seminal articles by Watson and Crick1,2 on the double helix structure of DNA. During these 40 years, a revolution in biology and genetics has occurred as the insights gained from this discovery have moved these fields to a new molecular level of understanding. During the past decade, we have also witnessed the beginning of another revolution in medical knowledge and therapeutics as the insights and techniques of molecular biology, molecular genetics, and recombinant DNA technology have begun to have an impact on medicine.
These advances in what is now being called molecular medicine are having an ever increasing impact on many areas of medicine: (1) molecular diagnostic techniques are moving diagnosis from the phenotypic to the genotypic level (eg, the sweat chloride test for cystic fibrosis vs the identification of a mutation in the cystic