It's all in the peas?
Tucked away in the solitude of a monastery located in the modern Czech republic, Gregor Mendel labored tirelessly documenting predictable patterns of traits transmitted through generations of ordinary peas. After eight years of devoted observations and documentation, Mendel published his theory of dominant and recessive inheritance in 1865 which countered the popular belief that offspring were a diluted blend of their parents. Instead, Mendel proposed, traits were expressed or masked depending on the mix of genetic material parents contribute. However, his theory of inheritance, was not widely accepted until the American scientist, Rollins Emerson, found similar patterns in his study of corn in 1900.
Proteins vs Nucleic Acid. Will the real genetic blueprint stand up.
Although Mendel, and later Emerson, explored the inheritance pattern of genetic traits, the mechanism of transmission was first entertained by the 25-year-old Swiss physician, Frederich Miescher, when he discovered that an acidic material found inside cell nuclei was present in every cell studied and speculated that this material may carry hereditary information.
Ironically, Miescher rejected his own theory but the material was later found to be DNA.
For the next 75 years, the prevailing scientific theory postulated that an organism's genetic blueprint was contained within its proteins until a group of scientists in New York City led by Oswald Avery determined through a series of complex experiments using bacteria that DNA was indeed the carrier of the genetic code. However, Avery's research was met with skepticism until 1952 when a second team confirmed that genetic transmission did not occur through proteins.
Cracking the DNA Code
In 1953, one year after confirming that DNA was in fact the genetic code, James Watson and Francis Crick, using an x-ray image of DNA captured by their colleague Rosalind Franklin, created the now famous double helix model of DNA.
Once the mystery of DNA structure was solved, scientific focus was placed on unlocking the message coiled inside the double helix. Working in his laboratory at the National Institutes of Health, Marshall Nirenberg deciphered the first letter of the code in 1961 and by 1966 the entire alphabet. He determined that the building blocks of DNA are groups of molecules known as nucleotides. Those four nucleotides, when strung together in varying combinations, provides the genetic map for a given organism.
Building on this knowledge over the next decade, scientists continued their journey in understanding our genetic code culminating in the development of a technique, called sequencing, developed by British biochemist Frederick Sanger that enabled us to replicate genetic material by imitating the body's process of DNA replication. Using his technique, Sanger published the first full genetic sequence, of a virus's relatively short genome. His efforts led to a Nobel Prize in chemistry three years later in 1980.
It's All In the Genes
The hunt for genetic variations linked to human disease became the focus of intense research over the next decade. In 1987, Francis Collins isolated the gene responsible for cystic fibrosis and one year later, the gene for Duchenne muscular dystrophy and Huntington's disease.
The evolution of genetics next led to the introduction of DNA evidence in court room proceedings in 1988 and the cloning of Dolly the sheep in 1996 and ultimately culminated in the completion of the Human Genome Project in 2003 after 13 years of collaborative effort between industry and academia, 18 countries, and about 200 laboratories in the United States alone.
Over the past dozen years the Herculean efforts of our scientific predecessors has enabled modern geneticists to diagnose complex patients with advanced genomic studies and oncologists to cure cancer with tumor genotyping. Future efforts will undoubtedly focus on understanding the synergistic effects of multiple genes in creating disease to unlocking the mystery of how genes are influenced by external factors such as the environment, lifestyle or medication, known as epigenetics.
Conclusion: A complex and rewarding journey
In summary, the scientific journey through modern genetics has spanned three centuries unlocking basic genetic principles from the observation of Mendel's peas to harnessing the power of genomics to diagnose, treat and cure human disease. The footprint of genetics will continue to expand and will likely impact every aspect of modern medicine, science and everyday life moving forward.
Fran Kendall, M.D.
This post is not meant to be a recommendation or a substitute for professional advice and services rendered by qualified doctors, allied medical personnel, and other professional services. The responsibility for any use of this information, or for proper medical treatment, rests with you.