An Overview of Molecular Genetics

Abstract

Sir Archibald Garrod concluded in the early 1900s that pre-disposition to disease is dependent on each individual’s chemi-cal composition (1). Beadle later described the one gene-one enzyme concept, which emphasized that biochemical processes are genetically controlled and that mutations in any given gene would result in a defective biochemical reaction (2). In 1953, Watson and Crick described for the first time the structure of the DNA molecule, now recognized as the “blueprint” of all living things (3). In their report, they described in detail the nature of complementary base‐pairing as part of the stoichiometry neces– sary for the double‐stranded DNA structure to maintain its integrity. The current concepts of molecular mechanisms of dis– ease have evolved from these early observations. Our ability to detect both intrachromosomal and extrachromosomal genetic alterations at the molecular level has led to a revolution in labo–ratory medicine, by promoting an understanding of molecular pathology (i.e., the molecular mechanisms of disease processes). The fact that many human diseases can now be asso– ciated with defects at the gene level has led to an understanding of the mechanisms of disease inheritance (4–8). Molecular genetics provides an avenue for dissecting complex pathophys‐ iological processes into specific gene defects. The functions and interactions of these genes has been termed “genomics” (9).