The leader of a $25 million expansionof the Cleveland Clinic’s reference lab has left and the health system has revised its plans for the project, including building a larger lab on its main campus but scaling back the lab’s future employment by 20 percent to 30 percent.

The Cleveland Clinic expects to break ground this summer on an expansion of its reference lab — a laboratory that does tests for other hospitals and medical facilities that can’t or don’t want to do the tests themselves. The lab could create 500 jobs in five years in Cleveland, and bring in national and international business.