Chemists and early biochemists determined the essential
building blocks of living cells and characterized their chemical
nature. Among these building blocks were nucleic acids, longchain
polymers composed of nucleotides. Nucleic acids were
named based partly on their chemical properties and partly on the
observation that they represent a major constituent of the cell
nucleus. That nucleic acids form the chemical basis for the transmission
of genetic traits was not realized until about 60 years ago
(1,2). Prior to that time, there was considerable disagreement
among scientists as to whether genetic information was contained
in and transmitted by proteins or nucleic acids. It was recognized
that chromosomes contained deoxyribonucleic acid as a primary
constituent, but it was not known if this DNA carried genetic
information or merely served as a scaffold for some undiscovered
class of proteins that carried genetic information. However, the
demonstration that genetic traits could be transmitted through
DNA formed the basis for numerous investigations focused on
elucidation of the nature of the genetic code. During the last halfcentury,
numerous investigators have participated in the scientific
revolution leading to modern molecular biology. Of particular significance
were the elucidation of the structure of DNA (3–9),
determination of structure–function relationships between DNA
and RNA (10,11), and acquisition of basic insights into the
processes of DNA replication, RNA transcription, and protein
synthesis (12–19). Molecular pathology represents the application
of the principles of basic molecular biology to the investigation
of human disease processes. Our ever broadening insights
into the molecular basis of disease processes continues to provide
an opportunity for the clinical laboratory to develop and implement
new and novel approaches for diagnosis and prognostic
assessment of human disease.