Genetics is the scientific study of heredity, one gene at a time. Genomics is the study of genomes, or the totality of the DNA of a single species. While genetics studies the laws of inheritance in an isolated and linear fashion, Genomics attempts to look at all our genes together as a flexible, dynamic system over time, interacting with and influencing our biochemical pathways and physiology.

The Human Genome Project is the mapping and sequencing of the entire human genome. The first draft of the entire human genome was published in April 2001, almost exactly one hundred years after the rediscovery of Mendel's "Laws of Heredity." The human genome consists of slightly more than 3 billion nucleotides (give or take a hundred million) and it codes for every protein and every enzyme made by the human body. Some 30,000 to 40,0000 thousand genes are thought to exist in the human genome, yet we know the function of slightly less than half of those genes.

The concept of "biochemical individuality" was first proposed by Roger Williams in 1956 to explain variability in disease susceptibility, nutrient needs, and drug responsiveness among otherwise seemingly healthy people. It is only in the wake of the ongoing genomic revolution, however, that predictive genetic testing has become available to allow us to assess true biochemical individuality. For the first time, physicians can gauge with increasing precision who is more likely to develop specific diseases, who will respond favorably (or react adversely) to a particular drug or supplement therapy, and finally, which nutrients are optimal for a particular individual's health and well-being.

As primary care practitioners, we stand at a critical crossroads where increases in availability of DNA-based testing and demand by patients for genetic information and advice necessitate our need to become both genetically literate and genomically competent.

New methods of investigating the genome are now being aimed at better understanding the multifactorial etiology of the most prevalent and debilitating health conditions that humans face-opening up the potential for astounding clinical applications.