KEY POINTS:
"Getting to know your genome can help you understand a little better why you are the way you are and in what ways you're similar to or different from your family, friends and neighbours."
So says the slick video on the 23andme website which offers those with about US$1000 to spare a way to read their DNA.
The California company, part-funded by Google, is just one of several offering direct-to-consumer genetics services. Those who want to know their genome receive a collection kit with instructions on how to take a cheek swab or saliva sample which is then couriered to the company's laboratory for DNA extraction and analysis.
What they get back is an on-line report of their genetic ancestry and a risk assessment of their genetic susceptibility to a range of diseases and conditions including heart disease, several types of cancer, obesity and diabetes.
The technology that makes this possible comes from advances in both genetics and a type of microchip. Massive studies like the Genome and HapMap projects have provided new genetic libraries about what's in our genes. Surprisingly, when it comes to DNA, humans are remarkably similar. What makes us different are small copying errors in the vast DNA alphabet of around 3.5 billion letters. It's these single letter variations - "snips" or single nucleotide polymorphism (SNPs) - that are grabbing all the attention. Scientists have begun to correlate certain SNPs to a range of physical traits and other attributes - such as your reaction to some drugs and your susceptibility to some diseases. The essential idea behind the direct-to-consumer genetic services is find the "snip" and you find the risk. But looking for 10 million SNPs among around two metres of microscopic strands of DNA is no easy task. Which is where the gene chips or microarrays come in. Minuscule amounts of gene sequences "printed" on to silicon in an orderly grid, provide up to 1.8 million "probes" of single stranded synthetic DNA. When a fluorescently labelled sample of DNA is introduced to the array it will stick - "hybridise" - to complimentary gene sequences and show up as a glowing spot on the grid. The chip is scanned and the results analysed by computer software.
"As doctors, we aren't sure that the results from these personal genome services are actually helpful to people," says pharmacogenomics researcher Dr Patrick Gladding. "If you find your heart attack risk is two times the normal, will that convince you to do more exercise and eat better?" There are concerns too that there is no definitive research of what percentage of people with the disease-associated SNPs will actually get the disease or get sick.
Most of the conditions scanned for are complex and thought to be caused by multiple gene variants and interactions among these variants and environmental factors. Someone may test positive for a gene associated with colon cancer but may have several other genes that protect from the disease - which may not be picked up by the personal genome services. Some may contract the disease even if they lack the gene.
Scientists and ethicists warn our understanding of genes is very much a work in progress. There is yet to be agreement about standards to measure the validity and usefulness of genetic markers especially those associated with disease. The worry is people could make life decisions based on incomplete or erroneous science. Some suggest users would be better off spending their US$1000 on on gym membership
But Gladding points out the technology is showing benefit for drug development and drug response. "How you respond to a drug doesn't tell you about the disease you might develop, it just tells you whether that drug will work or possibly not harm you."
The bigger concern is that we're rushing headlong into a world where both identity and destiny will be written in our genes. That raises a lot of unanswered questions. Who will keep and control this genetic information? Where will it be stored? Will we see a new form of discrimination against certain types of genes? Will consumers be able to keep their DNA information private from employers, potential spouses, insurers, and anyone else?
