Video encyclopedia

Down syndrome


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Woman with Down syndrome bakes her way to success

Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, characteristic facial features, and mild to moderate intellectual disability. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an 8 or 9-year-old child, but this can vary widely.