Combine this with some sort of blockchain straight on your DNA, you could have a permission system to grant/deny access to things, that would work not only for

Combine this with some sort of blockchain straight on your DNA, you could have a permission system to grant/deny access to things, that would work not only for your biological system, but with binding contracts on the real word. Like bad credit, or denying access to your bank account, to kill someone by making his system 'forget' how to process a given amino acid, or make them dependent of some drug to live so a government could just wait a "traitor" come to them so he/she can keep on living..