DNA Issues can be obtained by virtualizing too many times in a short amount of time.
The risk of developing an issue goes higher whenever you virtualize, and will go down if you rest on Earth for a bit. It is represented by the sweat particles that spawn while you are devirtualized.
Once you have an issue, you will be prompted to scan yourself in a Tower using the health scan program. You can also use a Scanner in diagnosis mode to scan your health.
There are currently two issues available on MRCL.
If you have an issue, you might randomly become invisible for a few seconds.
DNA degeneration is the first step of a DNA issue. It is also known as a light DNA issue.
It can be fixed in a tower by activating it or by completing a minigame at Sector Five's interface.
If left unchecked, this issue will develop into missing DNA sequences.
Missing DNA sequences are the the second and last step of a DNA issue. They're also known as a heavy DNA issue.
This issue is the result of not fixing a DNA degeneration issue fast enough.
Missing DNA sequences cannot be fixed in a tower, they have to be fixed by completing Sector Five's interface's minigame.
If you are devirtualized while you have this issue, you will be sent to Frontier. If you get a game over, the issue will be stopped. However, if you are saved, you will be sent back to Lyoko and your issue will go back to being a DNA degeneration.