Who We Serve: Down Syndrome

Down syndrome is the most common chromosomal anomaly, occurring approximately once in every 733 births. There are three major types of Down syndrome, the most common being Trisomy 21, which comprises 95% of the diagnoses. It is called Nondisjunction Trisomy 21, which means chromosome 21 did not disjoin from itself and divide evenly.

This happens at the beginning of cell division and the extra genetic material is copied in each ofthecells. There is another form called Translocation Trisomy 21, where part of the number 21 chromosome breaks off and attaches itself elsewhere, sometimes to the number 14 chromosome, or sometimes to the other number 21 chromosome. The third type of Down syndrome is a rare form called Mosaicism, in which the trisomy occurs a bit later in cell division, so only some of the cells contain and perpetuate it.

When the extra genetic material is located at the twenty-first chromosome, it is called Trisomy-21, which is also known as Down syndrome, after John Landgon Down, an English physician who first described the condition in 1866. Although individuals with Down syndrome have extra genetic material at the number 21 chromosome, all of their other chromosomes are normal. In fact, the material in the number 21 chromosome is normal as well there is just more of it. Down syndrome alters the normal course of mental and physical development, and is the leading cause of cognitive disabilities. Although there is great diversity regarding intelligence, learning styles, physical ability, creativity and personality, because of the influence of the other forty-six chromosomes in each individual's genetic blueprint.

The current, preferred terminology is Down syndrome. A child is a child first, so instead of a "Down's baby," you would say "a baby with Down syndrome". This phrasing is called "People First" language and applies to anyone with a learning difference or a physical difference.Down syndrome is part of more than 350,000 families in the United States. It occurs in all races, and at all socioecomic levels.

For More Information

Visit the Down Syndrome Indiana Website.