Info Technology World Wide

Part Two, Number 10

Technological applications in the tech area of "Personal Genomics".

10. Personal Genomics: The approximate number of DNA "letters" in each person's genome is said to be three billion. The Human Genome Project managed a complete, letter-by-letter sequence of a model human, a boon for research; but examining the specific genetic material of each patient in a doctor's office by wading through those three billion letters just isn't practical. So to achieve the dream of personalized medicine, a future in which a simple blood test will determine the best course of treatment based on a patient's genes, many scientists are taking a shortcut: focusing on only the differences between people's genomes.

Research is turning that strategy into a practical tool that will enable doctors and drug researchers to quickly determine whether a patient's genetic makeup results in greater vulnerability to a particular disease, or makes him or her a suitable candidate for a specific drug. Such tests could eventually revolutionize the treatment of cancer, Alzheimer's, asthma; almost any disease imaginable.

Genetic tests can already tell who carries genes for certain rare diseases like Huntington's, and who will experience the toxic side effects of a few particular drugs, but each of these tests examines only one or two genes. Most common diseases and drug reactions; however, involve several widely scattered genes, so researchers want to find ways to analyze an individual's whole genome. Since most genetic differences between individuals are attributable to single-letter variations called single-nucleotide polymorphisms, or SNPs. Identifying genomewide patterns of these variants that correspond to particular diagnoses or drug responses is the quickest, most cost-effective way to make patients' genetic information useful.

Special DNA wafers, small pieces of glass to which billions of very short DNA chains are attached, can be used to quickly and cheaply profile the millions of single-letter variants in a patient's genome. Researchers first created a detailed map of 1.7 million of the most common SNPs. Based on this map, they then designed a wafer that can detect which version of each one of these variants a specific patient has.

Some biologists argue that a truly accurate picture of an individual's genetics requires decoding his or her entire genome, down to every last DNA letter; but for now that is a daunting technical challenge that remains prohibitively expensive. SNP analysis is the quickest way to practically bring genetics and medicine together, and many geneticists share this vision of ultimately analyzing SNPs right in a doctor's office. Within a few years, genetic screening to predict a patient's drug response may become commonplace.