Celebrating World Down Syndrome Day

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ST. LOUIS, MO (KTVI) - It's an incredible day that's celebrated across the world.  March 21st is World Down Syndrome Day.

Down Syndrome was first identified in 1862 as a mental disability and people were institutionalized. It is celebrated on the 21st day of the third month of the year. It was chosen to symbolize the third copy of chromosome 21 present in Trisomy 21, the most common form of Down syndrome.

Down syndrome is usually caused by an error in cell division called non-disjunction. It is not known why this occurs, however it is known that the error occurs at conception and is not related to anything the mother did or did not do during pregnancy.

Advanced age of the mother can cause Down Syndrome. But, 80-percent of children with down syndrome are born to women under 35 years of age.

The incidence of Down syndrome in the United States is estimated to be 1 in every 700 live births.