BOSTON — Fenway Park, TD Garden, Gillette Stadium and other prominent landmarks will be lighted blue and yellow this week to mark World Down Syndrome Day.Organizers say Wednesday's colorful displays will commemorate an event the U.N. has observed since 2012, and to underscore how individuals with Down Syndrome need to be valued in their communities.World Down Syndrome Day is held annually on the 21st day of the third month to signify the tripling of chromosome 21 which causes the condition.