After half a dozen doctors over two years couldn't tell her what was wrong, she sent away for a 23andMe kit. At the time, the consumer DNA-testing company was only giving ancestry reports—the Federal Drug Administration had recently shut down 23andMe's health information ambitions. But a new doctor had recommended that Mitchell send in her spit anyway, and link her genetic profile to a third-party app that would analyze her DNA for clues.

It wasn't an FDA-approved test or a genetic panel that her insurance would cover. The app interpreted variations in her MTHFR gene, which were once thought to be linked to hundreds of conditions, before being mostly discarded by mainstream science. But Mitchell was desperate. The $100 she paid for the kit plus $50 for the app seemed a reasonable price under the circumstances. She brought the results to her first appointment with the new doctor and after taking a look, he suggested she switch up her supplements and stop eating gluten.