Early Childhood Education

Down Syndrome


Down Syndrome is a developmental disability resulting from a chromosomal abnormality. It is the most common chromosomal disorder, occurring in approximately one out of every 800 to 1000 births. In the United States, approximately 5,000 children are born with Down Syndrome each year. Furthermore, it is widely believed that with the increasing number of women postponing childbirth, the number of children born with Down Syndrome will rise dramatically over the next decade or so.

The description (and hence the name) of this syndrome is attributed to John Langdon Down, an English medical doctor, who wrote about it in his monograph entitled, Mental Affections of Childhood and Youth (1887). However, it was Jerome Lejeune, a French physician, who confirmed the condition as a chromosomal abnormality in 1959. The disorder was commonly referred to as mongoloidism (due primarily to the facial features of those affected by the disorder). Down Syndrome is now considered the more widely accepted and appropriate name for the disorder.

Individuals with Down Syndrome evidence a common set of physical characteristics, including low birth weight, short stature, low muscle tone, a flat-appearing face with a small nose and upwardly slanting eyes, skin folds on the corners of the eyes, an oversized tongue in relation to the size of the mouth, misshapen, low-set ears and small ear canals, broad short hands with only one crease on the palm, short fingers, hyper flexibility in the joints, and a large space between the great and second toes (sometimes referred to as a sandal gap).

The cause of Down Syndrome, also known as Trisomy 21, appears to be related to the age of the mother and is associated with a malfunction in human cell division. This can occur in one of three ways. The most common malfunction is a process known as nondisjunction, where, after cell division, there is an extra chromosome (or significant portion thereof) at the 21st chromosomal pair in every cell. This may occur before or at conception and accounts for approximately 95 percent of all cases of Down Syndrome.

A second and much less common cell division malfunction is called mosaicism. This results when the nondisjunction occurs after fertilization of the ovum and during early cell division. In this case, the extra chromosome at the 21st pair occurs in some cells but not others, yielding a pattern of cells, some with forty- six chromosomes and some with forty-seven chromosomes, much like a mosaic. Mosaicism accounts for 1-2 percent of all cases of Down Syndrome.

The third cell division malfunction resulting in Down Syndrome is also rare and usually occurs by chance. It is called translocation. In translocation, a piece of the 21st chromosome separates during cell division and attaches to another chromosome. The result is the normal set of forty-six chromosomes, but additional genetic material from chromosome 21 in each cell. Translocation accounts for 3-4 percent of all cases of Down Syndrome.

A suspicion of Down Syndrome is often made at birth based on the presence of one or more of the physical characteristics commonly associated with the syndrome. However, confirmation of the diagnosis requires karyotyping, that is, arranging the chromosomes under a microscope in order to group them by size, pattern, and shape; and to count them. Through this process, the extra number 21 chromosome can be found.

Down Syndrome is a disorder that is found in all racial and ethnic groups and across all socioeconomic levels. The incidence is greatest in older mothers, although in about 5 percent of cases, Down Syndrome originates with the father. Doctors can often estimate the risk that a pregnant woman will give birth to a baby with Down Syndrome. This estimate of risk, usually carried out between fifteen and twenty weeks of gestation, is based on a number of factors, including the amount of certain substances (alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol) in the mother’s blood. The age of the mother is also a risk factor in that the incidence of Down Syndrome increases with older women. However, 70-80 percent of children born with Down Syndrome are born to mothers under the age of 35. Further, a woman who has already had a child with Down Syndrome has a 1 percent chance of having another child with Down Syndrome. The screening process, along with a sonogram, is about 60 percent accurate in detecting a fetus with Down Syndrome.

Three pre-natal tests can be used to more reliably determine the presence or absence of Down Syndrome in the unborn fetus. Chorionic villi sampling (CVS) can be conducted as early as eight to twelve weeks’ gestation. Amniocentesis is usually performed between twelve and twenty weeks’ gestation. Percutaneous umbilical blood sampling (PUBS) is performed after twenty weeks. All three procedures extract tissue from the uterus for analysis and carry a risk of miscarriage. These tests, however, are 98-99 percent accurate in diagnosing Down Syndrome in the unborn fetus.

There are a number of medical conditions associated with Down Syndrome, including greater risk for heart disease, Alzheimer’s disease, and leukemia. In the early twentieth century, a child born with Down Syndrome would likely not live beyond age 10. With the discovery of antibiotics, such a child’s life expectancy doubled. Treatments for the characteristic medical conditions (i.e., heart defects, leukemia) associated with Down Syndrome have improved both life expectancy and health for those affected. Further advances in medical research continue to improve outcomes for individuals with Down Syndrome and its related medical conditions, and today many individuals with Down Syndrome live well into their fifties and beyond. However, it is still uncertain as to why individuals with Down Syndrome are at greater risk for these medical problems.

Down Syndrome is a developmental disability and individuals with Down Syndrome require a variety of therapeutic interventions (such as speech and language therapy, occupational therapy, and physical therapy) to address some of the characteristics of the disorder. Those affected with Down Syndrome also have varying degrees of mental retardation. Early intervention services and inclusive high-quality early childhood education have proven to be invaluable strategies to promote each child’s optimal development.

The passage of critical federal legislation has had a profound influence on the quality of life for individuals with Down Syndrome. The Individuals with Disabilities Education Act (first enacted in 1975 as P.L. 94-142, the Education of All Handicapped Children Act and most recently reauthorized in December 2004), along with other landmark legislation (the 1975 amendment to the Rehabilitation Act known as Section 504 and the Americans with Disabilities Act of 1990) have articulated the clear expectation that children and adults with disabilities, including Down Syndrome, have the right to access meaningful opportunities in education, housing, and employment; and to participate as fully as possible in their communities alongside individuals without disabilities.

Relevant provisions of the Individuals with Disabilities Education Act (IDEA), contained in Parts B and C, specify that children from infancy through age 21 are entitled to a free and appropriate public education in the least restrictive environment. These provisions encompass early intervention, early childhood, school, and vocational preparation programs; and presume that education and support services will be made available in inclusive settings.

Today, it is not only possible but desirable that children with Down Syndrome live, grow, and learn with their families and peers in their communities. For more information contact the National Down Syndrome Society at the following address:

National Down Syndrome Society

666 Broadway

New York, NY 10012


Further Readings: Down, John Langdon (1887). Mental affections of childhood and youth. London: Churchill; Lejeune, J., R. Turpin, and M. Gautier (1959). Le mongolisme. Premier example d’aberration autosomique humaine. Annales de genetique 1, 41-49; Selikowitz, Mark (1997). Down syndrome: The facts. 2nd ed. London: Oxford University Press.

Stephanie F. Leeds