21.   There is no cure and no known cause, although some researchers believe there may be a genetic link.

22.   There was no autopsy, no known cause of death, no sign of foul play.

23.   There is no known cause or cure.

24.   Whatever the case, hysteria, a psychological ailment with no known physical cause, multifarious symptoms and a checkered past, is more fashionable than ever.

25.   Diabetes causes many cases, but about a third have no known cause.

26.   Experts called the work important, noting that most cases of retardation have no known cause.

27.   However, local officials who refused to be identified denied that fireworks were the known cause.

28.   However, two-thirds of seizures have no known cause or are simply inherited.

29.   LeDoux learned in August he had primary sclerosing cholangitis, a rare liver disease with no known cause but a certain outcome without a transplant.

30.   Multiple sclerosis, which attacks the central nervous system, has no known cause and its symptoms can come and go.