Introduction

Works Cited:

http://go.galegroup.com/ps/retrieve.do?sgHitCountType=None&sort=RELEVANCE&inPS=true&prodId=GVRL&userGroupName=spar72416&tabID=T003&searchId=R1&resultListType=RESULT_LIST&contentSegment=&searchType=BasicSearchForm&currentPosition=2&contentSet=GALE%7CCX3447200207&&docId=GALE|CX3447200207&docType=GALE

http://ghr.nlm.nih.gov/condition/trisomy-18