Can i have multiple sclerosis and not know it? also, can ms cause ana titers to be positive?

No: Ms is a diagnosis based on clinical findings and certain tests, especially an MRI and spinal fluid. If you have no symptoms, you do not have ms. A positive ANA is possible but unusual.

A few comments: Yes, MS can be present and found coincidently on a brain MRI done for different reasons (Radiologically Isolated Syndrome). MS is not lupus or a rheumatological condition and does not cause the ANA titer to change. A positive titer may be meaningless if borderline, and a high titer would suggest an additional co-morbidity.