What is ALS? Explaining the disease that afflicts Dwight Clark

AP Photo/Bob Gabraith Former 49ers vice president Dwight Clark attends a news conference in 1998, Dwight Clark’s announcement Sunday night that he has been diagnosed with ALS surprised many 49ers fans — who may be wondering what the condition entails.

Here’s a deeper look at ALS, with background information gleaned from the ALS Association website and a Bay Area News Group feature on the disease.

How ALS affects afflicted

It severely hinders motor function, making such activities as moving, eating and breathing difficult.

The degenerative affliction is a progressive weakening of the muscles caused by nerve degeneration. Early symptoms include weakness in the arms or legs, slurred speech and…