Celebrate World Down Syndrome Day on Saturday, March 21. Normally, human chromosomes come in pairs, but people with Down syndrome have three instead of the usual two on number 21. So ten years ago, organizers chose March 21 (get it? 3-21) for World Down Syndrome Day. Don't miss their great new video, "My Opportunities, My Choices", with interviews with people with Down syndrome from 39 countries looking at their enjoyment of full and equal rights and the role of their families. This global video event is presented for World Down Syndrome Day, Saturday March 21, 2015, by Down Syndrome International.