Down Syndrome Definition of Down Syndrome Down Syndrome, congenital malformation accompanied by moderate to severe mental retardation, and caused by a chromosomal abnormality. The chance of getting Down syndrome is approximately one in 700 births, but the risk varies with the age of the mother. The incidence of Down syndrome in children born to 25-year-old mothers is approximately 1 in 1200; the risk increases to approximately 1 in 120 for women older than 40 years. Prenatal tests like amniocentesis and chronic …showed first 75 words of 1905 total…

…showed last 75 words of 1905 total…