Would you want to know whether your genes put you at a high risk for developing arthritis? I did. My youngest sister was diagnosed with rheumatoid arthritis as an infant, and my mother’s had RA for most of her adult life. Now in my early 30s, I’ve remained free of the disease, but given that I have another autoimmune condition, psoriasis, and am prone to weather-related joint aches, I’ve always felt that it was only a matter of time before I, too, would be diagnosed with RA.

That’s why I signed up to have my DNA tested through 23andMe, a direct-to-consumer genomics testing company. Along with Navigenics and deCODEme, 23andMe is one of a very small handful of for-profit direct-to-consumer companies that examine DNA for thousands of genetic variants, known as single nucleotide polymorphisms, or SNPs (pronounced  “snips”).  

All DNA is comprised of a four-letter code. The way those letters are shuffled in our genes determines what proteins are made by the body. An SNP is simply a one-letter change in a stretch of DNA – from AGCTA to AACT, for example. Most of the time, that one-letter difference won’t have any affect, but in some cases, SNPs can causes diseases, such as cystic fibrosis. In other cases, SNPs may play a role in how different people respond to the same medication, or they may simply be markers for regions of genes involved in disease.

For $429, the company mailed me a kit containing a small vial to fill with saliva. After I mailed it back, they examined the DNA in my saliva in order to create my “genetic profile,” which I accessed on their website. 

The profile was extensive: in addition to revealing my predisposition for dozens of different diseases and conditions, including RA, osteoarthritis (OA), Sjogren’s syndrome, lupus and gout, it also revealed the regions my ancestors likely descended from, and a smattering of random traits, ranging from the curious (whether I can taste bitter food) to the potentially useful (whether I’m likely to be resistant to antidepressants). 

23andMe makes it clear that not all the genetic information they provide holds the same significance. Instead, it divides health results into two groups: clinical reports, which are a list of diseases, conditions and traits for which there are genetic associations supported by multiple, large, peer-reviewed studies, and which have what they deem a substantial influence on a person’s chances of developing the disease or having the trait; and research reports, which are associations based on smaller studies that, in many cases, have not been replicated.

An Incomplete Picture

Because of my family history, my general practitioner and I have both long assumed that my genes must elevate my odds of RA. So imagine my surprise when my 23andMe clinical report concluded that I was at a below-average risk overall. Only one of the six RA-related SNPs that 23andMe examines indicated a high RA risk.

I wanted to believe that the results meant I’d won the genetic lottery – that unlike my sister, my knees would never swell to twice their size, and that unlike my mother, I’d never struggle to get out of bed on particularly cold and wet days. But when I spoke with Peter Gregersen, MD, who is head of the Robert S. Boas Center for Genomics and Human Genetics at The Feinstein Institute for Medical Research Manhasset, N.Y., he explained that unfortunately, I wasn’t exactly in the clear.