IBD, inflammatory bowel disease is composed of two diseases: Crohn’s Disease, and ulcerative colitis.
MS is an autoimmune disease where the T cells of our immune system think the cells of the myelin sheath, the nerve covering, is foreign and must be attacked. This arbitrary attack affects the brain, spinal cord and the optic nerve and creates a a variety of symptoms. More women than men have MS. Genetics play a role.
Spondylo means vertebrae or bones in your back. So, you can see that AS affects the spine. With the progression of disease, the vertebral joints fuse causing the spine to be stiff.