Down syndrome is a naturally occurring genetic condition that affects approximately 1 in 800 babies born worldwide. It is a result of extra genetic material associated with the 21st chromosome and impacts individuals across all racial, gender, and socio-economic lines. While Down syndrome affects people differently, individuals with this condition can lead fulfilling, productive lives with the right support and resources.
What is Down Syndrome?
Down syndrome occurs when an individual has an extra copy of chromosome 21, resulting in 47 chromosomes instead of the usual 46. This extra genetic material affects the way the body and brain develop. People with Down syndrome often have mild to moderate cognitive delays, but they also have unique strengths, talents, and abilities.
The effects of Down syndrome vary widely, meaning each person with the condition is unique. Physical characteristics, health challenges, and learning styles can differ from individual to individual, but with proper support, individuals with Down syndrome can achieve their goals and live independently.
The Three Types of Down Syndrome
There are three types of Down syndrome, all of which are caused by differences in how chromosome 21 is copied or arranged. Though the types differ genetically, individuals with all forms of Down syndrome can have similar physical traits and developmental challenges.
1. Trisomy 21 (Nondisjunction)
This is the most common form of Down syndrome, accounting for about 95% of cases. In Trisomy 21, there is an error during cell division, and an individual has three copies of chromosome 21 in all of their cells instead of the usual two. This occurs randomly and is not inherited. Trisomy 21 is often simply referred to as “Down syndrome.”
2. Translocation Down Syndrome
Translocation Down syndrome occurs in about 3% to 4% of cases. In this type, an extra part or whole copy of chromosome 21 is attached, or “translocated,” to a different chromosome, usually chromosome 14. Unlike Trisomy 21, translocation can be inherited from a parent who may be a carrier of the translocated chromosome. Genetic testing can help determine if a parent carries this translocation.
3. Mosaic Down Syndrome
Mosaic Down syndrome is the rarest type, found in about 1% to 2% of individuals with Down syndrome. In this form, some of the individual’s cells have three copies of chromosome 21 (like in Trisomy 21), while other cells have the typical two copies. This “mosaic” of cell types occurs due to an error in cell division shortly after fertilization. Individuals with mosaic Down syndrome may have fewer characteristics of the condition, but they can still experience similar developmental and health challenges.
Living with Down Syndrome
Individuals with Down syndrome are valued members of our community, and with the right opportunities, they can achieve a high quality of life. Advances in education, healthcare, and support services have significantly improved outcomes for people with Down syndrome. Many individuals attend school, hold jobs, form meaningful relationships, and contribute in various ways to their communities.
DSAS is committed to raising awareness, advocating for rights, and providing resources for individuals with Down syndrome and their families. We believe that everyone, regardless of ability, deserves the chance to thrive and succeed.