Monozygous twins discordant for multiple sclerosis. Report of one pair and discussion of possible causes of multiple sclerosis.

One pair of male monozygous twins was examined: only 1 twin had multiple sclerosis. Differences in the life histories of the twins were identified. Haematological, biochemical and microbiological studies were performed. It is possible in theory to determine which environmental factors may have been responsible for the development of multiple sclerosis in 1 twin. Several differences in life history were found in this study.