The Rev. Jesse Jackson Sr. has been diagnosed with Parkinson’s disease, the civil rights icon announced Friday afternoon in an open letter to the public. The neurodegenerative disorder is not deadly, but there is no cure.

“After a battery of tests, my physicians identified the issue as Parkinson’s disease, a disease that bested my father,” Jackson, 76, wrote on the website of his organization, the Rainbow/PUSH Coalition. “Recognition of the effects of this disease on me has been painful, and I have been slow to grasp the gravity of it. For me, a Parkinson’s diagnosis is not a stop sign but rather a signal that I must make lifestyle changes and dedicate myself to physical therapy in hopes of slowing the disease’s progression.”

The disease affects people differently, but generally manifests itself with hand tremors, slow movements, stiffness in limbs and trouble maintaining balance, according to the Parkinson’s Foundation.

It was not immediately clear when exactly Jackson was diagnosed, but he has found it “increasingly difficult to perform routine tasks, and getting around is more of a challenge” after he and his family “began to notice changes about three years ago.”

There is no cure for the disease. Jackson said in his letter than he planned to “make lifestyle changes and dedicate myself to physical therapy in hopes of slowing the disease’s progression. However, the unfortunate reality was that all forms of therapy for the disorder can “improve symptoms” but have never stopped Parkinson’s from progressing at its typical rate.

While Jackson said his father suffered from the same disease, it is not hereditary, according to the Michael J. Fox Foundation, named for the actor who also has Parkinson’s.

“Only about 10 percent of Parkinson’s cases have been linked to a genetic cause,” the website wrote. “Most cases of Parkinson’s are called idiopathic or sporadic, meaning the cause is unknown, and researchers believe onset is due to a combination of genetic and environmental factors.”

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