Answer:
A person who has the genetic disorder Down syndrome often has an extra chromosome. Most people receive 23 chromosomes from each parent, 46 in all. Sometimes, one of the chromosomes makes an extra copy of itself, giving the person 47 chromosomes. This extra chromosome may cause developmental disabilities, such as delayed motor and language skills. People with Down syndrome do not all show the same symptoms, but many have hearing and vision problems, learning disabilities, or heart problems.
