Making a list of chronic diseases which manifest randomly (ex. epilepsy) and finding ways to predict attacks.

Atrial fibrillation as an example

[ From wikipedia ]
Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating.[1] Often it starts as brief periods of abnormal beating which become longer and possibly constant over time.[2] Most episodes have no symptoms.[3] Occasionally there may be heart palpitations, fainting, shortness of breath, or chest pain.[4] The disease increases the risk of heart failure, dementia, and stroke.[3] In atrial fibrillation the P waves, which represent depolarization of the top of the heart, are absent.