Fig. 1.

The factors that may contribute to the development and progression of multiple sclerosis. The precise causal factors of multiple sclerosis are unknown. However, it is possible that multiple factors are involved in causing multiple sclerosis, including DNA defects in nuclear and mitochondrial genomes, viral infection, hypoxia and oxidative stress, lack of sunlight or sufficient levels of vitamin D, and increased macrophages and lymphocytes in the brain.