What is Down Syndrome/Trisomy 21?
- Down syndrome is the most commonly occurring chromosomal condition, occurring once in every 691 babies born.
- The medical term for Down syndrome is also referred to by the name Trisomy 21. There are normally 46 chromosomes in each cell, 23 inherited from the mother and 23 from the father. When some or all of a person’s cells have an extra full or partial copy of chromosome 21, the result is Down syndrome. Down syndrome is caused by a person having three copies of chromosome 21 instead of two copies. The picture above shows a genetic analysis of a person with Down syndrome. You will notice that the arrow is pointing to the set of number 21 chromosomes. It is important to understand that all of the chromosomes of this person are normal. It is the fact that there is an extra chromosome that causes Down syndrome.
- It is a random occurrence in nature — nothing that a mother or father has done before or during the pregnancy causes Down syndrome.
- It occurs in people of all races and economic levels.
- While it is statistically more likely for a woman over 35 to conceive a child with Down syndrome, 80% of children born with Down syndrome have mothers under 35.
- There are more than 400,000 individuals living with Down syndrome in the United States.
- The life expectancy for people with Down syndrome has increased dramatically in recent decades – from 25 in 1983 to 60 today.
- As members of society, individuals with Down syndrome benefit from loving homes, education, positive public attitudes and a supportive community environment. Early intervention programs, offered through various community resources, address developmental delays so that children with Down syndrome can reach their full potential and enjoy productive lives.