Scientists at Myriad Genetics of Salt Lake City have identified a gene that causes depression. The finding could revolutionize treatment of the condition.

Myriad and Abbott Laboratories are working to develop a new class of antidepressants.

Currently used medicines such as Prozac, work on 70 percent of patients, but 30 percent don't improve. Of those who do, as many as half still suffer some symptoms of depression in spite of the medication.

Though this is an exciting development, there could be several genes involved in this complex disease. New medications could take some time to develop.