<prompt> Trisomy 21 is -Downs syndromeTurner syndromeKleinfelter syndromeEdward syndrome  <response>: Ans. is a i.e., Dow ns syndrome Trisomy 21 is synonymous with downs syndrome and is the most common of the chromosomal disorders o Downs syndrome - Trisomy 21 o Edwards syndrome - Trisomy 18 o Patau syndrome - Trisomy 13 o Kleinfelter syndrome - 47XXY o Turner syndrome - 45 XO 