Actually, we do not know what causes most cases of breast cancer.

One case in five is caused by stroke around the time of birth.

As of June 8, 195 cases caused by the other two had been identified worldwide.

Nuclear waste, we are told, caused many deaths and cases of cancer.

In fact we don't yet understand the human mind well enough to say for sure exactly what causes most cases of amnesia.

But most cases of colon cancer are not caused by changed genes.

But some cases of glaucoma aren't caused by increased pressure.

Some cases are caused by a genetic defect, which may run in families.

About a quarter of cases are caused by a genetic disorder.

But some cases of vertigo are caused by head injuries.