Analyzing epigenetic profiles from blood samples may not accurately reflect other tissues, and accuracy is difficult to verify without biopsies.

“using a blood sample uh as a matter of trying to get the epigenetic profile for what's going on in your brain or your pancreas doesn't always work and it's hard to even know whether or not it works because it's not as if we're going in and doing pancreatic or brain biopsies on most people”