Trisomy 21 (Down Syndrome)
- There are three types of Down syndrome: trisomy 21 (nondisjunction) accounts for 95% of cases, translocation accounts for about 4%, and mosaicism accounts for about 1%
- Down syndrome is the most commonly occurring chromosomal condition. Approximately one in every 700 babies in the United States is born with Down syndrome – about 6,000 each year
- Down syndrome occurs in people of all races and economic levels
- The incidence of births of children with Down syndrome increases with the age of the mother. But due to higher fertility rates in younger women, 80% of children with Down syndrome are born to women under 35 years of age
- People with Down syndrome have an increased risk for certain medical conditions such as congenital heart defects, respiratory and hearing problems, Alzheimer’s disease, childhood leukemia and thyroid conditions. Many of these conditions are now treatable, so most people with Down syndrome lead healthy lives
- A few of the common physical traits of Down syndrome are: low muscle tone, small stature, an upward slant to the eyes, and a single deep crease across the center of the palm. Every person with Down syndrome is a unique individual and may possess these characteristics to different degrees or not at all
- Life expectancy for people with Down syndrome has increased dramatically in recent decades – from 25 in 1983 to 60 today
- People with Down syndrome attend school, work, participate in decisions that affect them, have meaningful relationships, vote and contribute to society in many wonderful ways
- All people with Down syndrome experience cognitive delays, but the effect is usually mild to moderate and is not indicative of the many strengths and talents that each individual possesses
The incidence of Down syndrome is between I in 1000 to 1 in 1,100 live birth worldwide.
- Each year, approximately 3,000 to 5,000 children are born with Down syndrome.
- 60-80% of children with Down syndrome having hearing issues
- 40-45% of children with Down syndrome have congenital heart disease
Trisomy 18 (Edwards Syndrome)
- It is also known as Edwards Syndrome
- It is a condition caused by an error in cell division
- An extra chromosome in 18 develops
- Occurs in 1 out of every 2500 pregnancies in the United States
- It is 1 in 6000 live births
- Only 50% of babies who are carried to term will be born alive
- Children are often born with heart defects
- Features include a small head, small jaw, clenched fists and severe intellectual disabilities
- It is named after John Hilton Edwards, who first described the syndrome in 1960
- It affects different organ systems
Trisomy 13 (Patau Syndrome)
- Trisomy 13 is the presence of an extra chromosome 13 in all cells
- Mosaic trisomy 13- the presence of an extra chromosome in some of the cells
- Partial trisomy 13- the presence of a part of extra chromosome 13 in the cells
- Occurs in about 1 out of every 5,000 to 16,000 newborns
- The brain is mostly affected
- Most children tend to have a heart defect
- Was first described in 1657
- 44% of babies born die within the first month of birth
- In the first month of birth, 69% die by 6 months
- Only 18% reach their first birthday
- It is not inherited
- Are usually born with an intellectual disability.