The personal genome and the practice of cardiovascular medicine

Recent advances in the DNA sequencing techniques have made it possible to sequence the entire protein coding regions of the genome and even the entire genome at a reasonable cost. Genetic discoveries, facilitated by these advances, have illustrated the enormous genetic diversity of the mankind. Accordingly, the genome of each individual has about 4 million sequences that are different from the general population, including a significant number of unique sequence variants. About 3 million of these variations affect 1 of the 3 billion bases in the genome, while the rest affect from 2 to several million base pairs of DNA. About 10,000 of these variants in each genome changes the amino acid sequence and hence, the protein structure. The biological and clinical significance of these DNA sequence variants follow a gradient that ranges from negligible to large. A small number of variants impart large effect sizes but those with negligible and small effect sizes are quite abundant in the genome. The most important contributions of these variants are likely to be in providing insights into the molecular mechanisms responsible for diseases, which is essential for the ultimate cure of the human disease. These genetic variants also influence susceptibility to diseases, responses to treatment and clinical outcome. Variants with large effect sizes have the potential to serve as diagnostic markers, prognosticators as well as individualization of therapy. The daunting challenge in the upcoming years is to identify the variants that have significant clinical impacts from those that impose no discernible effects. The landscape of the practice of medicine is expected to change with the incorporation of the information content of the DNA sequence variants into the routine practice of medicine. The medical community needs to be prepared to best utilize the information that will be available from "personal genomes" of the patients.