Down Syndrome Awareness Shirt Co. Down Syndrome Awareness Design Down Right Perfect. World Down Syndrome Day (WDSD) is observed on March 21st. Show your love for the special person in your life. Three #21 chromosomes or Trisomy 21 results in down syndrome. Observe World Down Syndrome day on 3/21. A positive down syndrome design for anyone wanting to wear blue and yellow ribbons and designs to support down syndrome awareness. A cute T21 Tribe Design. Click our brand name for more apparel styles and gifts.