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Understanding Down Syndrome


What is Down syndrome?

Down syndrome is the most common genetic condition. One in every 733 babies is born with Down syndrome. The most common form of Down syndrome is called Trisomy 21, because it involves an extra copy of the 21st chromosome.

What impact does Down syndrome have on society?

Individuals with Down syndrome are becoming increasingly integrated into society and community organizations, such as school, health care systems, work forces, and social and recreational activities. Individuals with Down syndrome possess varying degrees of intellectual disabilities, from very mild to severe. Most people with Down syndrome have IQs in the mild to moderate range of intellectual disability.

Due to advances in medical technology, individuals with Down syndrome are living longer than ever before. In 1910, children with Down syndrome were expected to survive to age nine. With the discovery of antibiotics, the average survival age increased to 19 or 20. Now, with recent advancements in clinical treatment, most particularly corrective heart surgeries, as many as 80% of adults with Down syndrome reach age 60, and many live even longer.

In the United States, approximately 400,000 families have a child with Down syndrome, and about 5,000 babies with Down syndrome are born each year. More and more Americans will interact with individuals with this genetic condition, increasing the need for widespread public education and acceptance.

What is the cause of Down syndrome?

The additional copy of the 21st chromosome which causes Down syndrome can originate from either the father or the mother. Approximately 5% of the cases have been traced to the father.

Who has the highest risk of having a child with Down syndrome?

Down syndrome can occur in people of all races and economic levels. Older women have an increased chance of having a child with Down syndrome. A 35-year-old woman has about a one in 350 chance of conceiving a child with Down syndrome, and this chance increases gradually to one in 100 by age 40. At age 45 the incidence becomes approximately one in 30.

Since many couples are postponing parenting until later in life, the incidence of Down syndrome conceptions is expected to increase. Therefore, genetic counseling for parents is becoming increasingly important. Still, many physicians are not fully informed about advising their patients about the incidences of Down syndrome, advancements in diagnosis, and the protocols for care and treatment of babies born with Down syndrome.

Why are medical researchers today so interested in Down syndrome?

Down syndrome is a developmental condition. As researchers learn more about the molecular genetics and other aspects of Down syndrome, they also obtain valuable information about human development and can advance the study of many biological processes.

In addition, individuals with Down syndrome have a higher incidence of certain medical conditions, and the study of Down syndrome may yield important breakthroughs in those areas. Research in Down syndrome provides a way for looking at many important problems:

  • Heart disease: Up to 50% of individuals with Down syndrome are born with congenital heart conditions. The majority of heart conditions in children with Down syndrome can now be surgically corrected with resulting long-term health improvements. However, scientists continue to search for the cause of these heart conditions and look for means of prevention.
  • Alzheimer's disease: Estimates vary, but it is reasonable to conclude that 25% or more of individuals with Down syndrome over the age of 35 will develop the clinical signs and symptoms of Alzheimer's-type dementia.
  • Leukemia: Approximately one in every 100 individuals with Down syndrome will develop leukemia; or, to put it another way, 99% of people with Down syndrome will not develop leukemia. The majority of cases are categorized as acute megakaryoblastic leukemia, which tends to occur in the first three years of life, and for which there is a high cure rate. A transient form of leukemia is also seen in newborns with Down syndrome, disappearing spontaneously during the first two to three months of life.

 

Down Syndrome Facts

  • Down syndrome occurs when an individual has three, rather than two, copies of the 21st chromosome. This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome.
  • Down syndrome is the most commonly occurring chromosomal condition. One in every 733 babies is born with Down syndrome.
  • There are more than 400,000 people living with Down syndrome in the United States.
  • 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, 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.
  • Quality educational programs, a stimulating home environment, good health care, and positive support from family, friends and the community enable people with Down syndrome to develop their full potential and lead fulfilling lives.
  • Researchers are making great strides in identifying the genes on Chromosome 21 that cause the characteristics of Down syndrome. Many feel strongly that it will be possible to improve, correct or prevent many of the problems associated with Down syndrome in the future.

MEDICAL INFORMATION

People with Down syndrome are at increased risk for certain health problems compared to the general population. This section offers information about these health issues.

People with Down syndrome also have specific health care needs, above and beyond standard medical care. Additionally, children with Down syndrome grow and develop at different rate than their typical peers. This section also includes health care guidelines, growth charts, and information about specialty clinics, specific to people with Down syndrome.

Growth Charts

Children with Down syndrome are generally smaller than their typically-developing peers, so Down Syndrome Growth Charts have been created by physicians. The percentile curves on the charts were derived from a longitudinal study examining the growth patterns of individuals with Down syndrome.

Click here for a complete list of downloadable growth charts for boys and girls from ages 0-18

Health Care Guidelines

Down Syndrome Health Care Guidelines follow and individual's development from birth through adulthood and provide information about potential health concerns at each stage. They are compiled by the Down Syndrome Medical Interest Group, a national affiliation of health care providers who specialize in caring for individuals with Down syndrome. More information on medical guidelines and associated medical conditions is available from the National Down Syndrome Society.

Click here for a complete list of downloadable Health Care Guidelines

DSAMT is a 501(c)3 nonprofit organization funded by private support from individuals, foundations, community organizations and fundraising efforts.