"A constellation of symptoms that occur as a result of the presence of a complete third copy of the 18th chromosome. Characteristics include profound mental retardation and severe malformations. Individuals with this syndrome rarely live past one year.NCI" . "Complete Trisomy 18 Syndrome"^^ . "Complete Trisomy 18 Syndrome"^^ . . . "Disease or Syndrome"^^ . "Complete Trisomy 18 SyndromePTNCI" . "C101362"^^ . "Complete Trisomy 18 SyndromePTNICHD" . . "C0152096"^^ . . "NICHD"^^ . .