Providing education, support, and advocacy to those individuals, their families, friends, and professionals in the Eastern Iowa area that are blessed by Down syndrome.
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FACTS ABOUT DOWN SYNDROME
Down syndrome is a common genetic variation which usually causes delay in physical, intellectual and language development. The exact causes of the chromosomal rearrangement and primary prevention of Down syndrome are currently unknown. Down syndrome is one of the leading clinical causes of cognitive delay in the world. It is not related to race, nationality, religion or socio-economic status. The incidence of Down syndrome in the United States is estimated to be 1 in every 700 live births. Of all children born in this country annually, approximately 5,000 will have Down syndrome. Approximately a quarter of a million families in the United States have a member who has Down syndrome. While the likelihood of giving birth to a child with Down syndrome increases with maternal age; nevertheless, 80% of babies with Down syndrome are born to women under 35 years of age, as women in that age group give birth to more babies overall. There is wide variation in mental abilities, behavior and physical development in individuals with Down syndrome. Each individual has his/her own unique personality, capabilities and talents. 30% – 50% of the individuals with Down syndrome have heart defects and 8% – 12% have gastrointestinal tract abnormalities present at birth. Most of these defects are now correctable by surgery. Individuals with Down syndrome benefit from loving homes, early intervention, inclusive education, appropriate medical care, and positive public attitudes. In adulthood, many persons with Down syndrome hold jobs, live independently and enjoy recreational opportunities in their communities. |
TYPES OF DOWN SYNDROME
Trisomy 21 (Nondisjunction) Down syndrome is usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate. As the embryo develops, the extra chromosome is replicated in every cell of the body. This type of Down syndrome, which accounts for 95% of cases, is called trisomy 21. Translocation Translocation accounts for about 4% of all cases of Down syndrome. In translocation, part of chromosome 21 breaks off during cell division and attaches to another chromosome, typically chromosome 14. While the total number of chromosomes in the cells remains 46, the presence of an extra part of chromosome 21 causes the characteristics of Down syndrome. Mosaicism Mosaicism occurs when nondisjunction of chromosome 21 takes place in one – but not all – of the initial cell divisions after fertilization. When this occurs, there is a mixture of two types of cells, some containing the usual 46 chromosomes and others containing 47. Those cells with 47 chromosomes contain an extra chromosome 21. Mosaicism accounts for about 1% of all cases of Down syndrome. Research has indicated that individuals with mosaic Down syndrome may have fewer characteristics of Down syndrome than those with other types of Down syndrome. However, broad generalizations are not possible due to the wide range of abilities people with Down syndrome possess. |
