What type of disease Alan in the movie dear john suffering from?

In "Dear John," Alan suffers from Guillain-Barré syndrome (GBS), a rare autoimmune disorder that affects the nervous system. GBS causes the immune system to attack the body's own nerve cells, leading to muscle weakness and, in severe cases, paralysis. The progression of the condition can vary from person to person, and recovery may take months or even years. In the movie, Alan's GBS is portrayed as a life-altering condition that impacts his relationship with his loved ones and career in the military.