The defendant may say you did not seek treatment quickly enough or you did not do everything your doctor asked, as far as seeking additional treatment or testing. Your lawyer can counter this defense with your medical records by showing what you told your doctor and the treatment you underwent. The goal is to show that you did your part to get treatment.
It is important to be detailed when discussing symptoms of an illness with your doctor, this includes providing relevant family history of an illness. If you omit details and you are misdiagnosed, it may be harder to prove your case.