In our quest to understand better how our genes foretell everything from our personal quirks to what diseases we may develop, geneticists spent another year poring into various nooks and crannies of the human genome.
23andMe, a retail DNA testing service, has compiled their findings into a top 10 list of genetic findings -- though I'll tell you right now that it's really a top nine list plus one "finding" that's less about genetics and more about the way 23andMe is using the web to upend traditional research methods.
But, to get on with the list.
1. Genetic breakthroughs in understanding Parkinson's
There were three big findings in Parkinson's this year: First, in March, Stanford scientists were able to re-create features of the disease in a petri dish using the cells of a patient (who is actually Google founder Sergey Brin's mom, Genia Brin); the new cells began accumulating the same kinds of proteins that characterize Parkinson's.
Then in June, 23andMe published a study in PLoS Genetics found two novel genetic associations with Parkinson's disease. The company then found, in October, another gene that may provide protection against the disease.
2. Genetic factors for type 2 diabetes the same in people of South Asian and European descent
People of South Asian descent have higher rates of type 2 diabetes than those of European ancestry. A study of almost 60,000 people of South Asian ancestry found several genetic variants associated with type 2 diabetes, and those appeared also to be linked to the disease in Europeans. Another previous study had also found genetic factors linked to the disease in Europeans, and those same variants appeared to be linked to the disease in South Asians. However, most of the genetic variants are stronger in one population or the other.
3. In our genes, obesity is affected by age
Want to know your genetic predisposition to obesity? Check out the FTO gene ... and your age. One study showed that the same obesity-linked genetic variant had an opposite correlation with body mass index in very young children than it did in older children.
4. You can see your genes in the mirror
Take a close look in the mirror ... right at your eyeball. An Australian study of nearly 3,000 people showed that a few genetic variants contribute to the flecks, rings and spots in our irises.
5. The importance of sex in genetic research
Just as diseases affect men differently from how they affect women, genetic factors can have opposite effects in men vs. women or an effect in one sex but not the other. Unfortunately, most genetic research ignores these sex differences. However, a Stanford study found that genetic variants associated with Crohn's disease and coronary heart disease affected the sexes differently. Lead author Linda Liu concluded, “studying sex differences can help provide a missing link in terms of different gene-endocrine and gene-environment interactions in males and females.”
6. Greater understanding of breast cancer and prostate cancer
It was known that women with high mammographic density have four to five times higher risk for breast cancer. Last January, a study found a genetic variant that was linked both toe mammographic breast breast density and breast cancer risk.
A lot is known about genetic factors related to prostate cancer in Europeans, but less about those in African Americans. A study last May showed that only half the genetic factors associated with prostate cancer in those of European ancestry were also linked to that type of cancer in African Americans.
7. Importance of participant-driven research
Okay, this is the one that isn't really a genetic finding: 23andMe has been working on two research initiatives that "show the power of participant-driven research" in which the company solicits research participants via the web and monitors them through online surveys to study diseases such as Sarcoma or to study genetic links to diseases in the African-American population, which is understudied.
8. Got a migraine? Check your genes
In June, the largest migraine study to date found three genetic variants associated with migraines.
9. Multiple autoimmune disorders may share genetic links
In August, a study was published on genetic variants previously linked to autoimmune disorders. It found that half of more than 100 genetic variants studied were associated with at least two autoimmune conditions, such as rheumatoid arthritis, multiple sclerosis, lupus, and psoriasis.
10. Diving deeper into our African origins
It was thought that the human species originated in eastern Africa. But research published by researchers at Stanford, UCSF and 23andMe last March showed that our ancestral origins may actually be in southern Africa. 23andMe scientists also found that 3% to 4% of people who identify as entirely of European descent had some some hidden African ancestry.