1.   According to one school of thought, the disease is caused by a genetic defect.

2.   But the role of the fungus in causing human disease is less well understood.

3.   Doctors are beginning to understand what causes the disease.

4.   Indeed, asbestos is a prime example of how Marginal exposure to carcinogens does not cause disease.

5.   One woman died despite intensive treatment and none had been exposed to radiation or other factors known to cause the disease.

6.   Scientists are trying to find out what causes the disease.

7.   The disease is caused by a defective gene.

8.   The fumes have caused skin diseases among the villagers.

9.   The result is a hybrid virus that will multiply readily when given to humans but will not cause disease.