Children with Down's syndrome have multiple malformations, medical conditions and cognitive impairment because of the presence of extra genetic material from chromosome 21. The Down's syndrome phenotype is variable and the degree of cognitive impairment may be mild, moderate or severe. Children with Down's syndrome often function more effectively in social situations than would be predicted on the basis of their cognitive assessment results.1
This is a companion discussion topic for the original article at https://patient.info/doctor/congenital-disorders/downs-syndrome-trisomy-21