The National Institutes of Health has developed a research plan to advance understanding of Down syndrome and speed development of new treatments for the condition, the most frequent genetic cause of mild to moderate mental retardation and associated medical problems.
The plan sets research goals for the next 10 years that build upon earlier research advances fostered by the NIH.
"Through the years, the NIH research effort has led to increased understanding of Down syndrome," said Elias Zerhouni, M.D., director of the National Institutes of Health. "We are now poised to capitalize on these advances and improve the health of people with Down syndrome."
Down syndrome occurs in 1 out of every 800 births in the United States. Down syndrome most frequently results from an extra copy of chromosome 21 in the body's cells.
In most cases, this extra chromosome comes from the mother. In some cases, forms of Down syndrome can result from just having an extra portion of chromosome 21. The chance of giving birth to a baby with Down syndrome increases as women age.
Infants with Down syndrome have certain characteristic physical features, such as short stature, distinctive facial features and are more likely to have health conditions like hearing loss, heart malformations, hypertension, digestive problems, and vision disorders.
Although Down syndrome is the most common cause of mild to moderate intellectual disability, the condition occasionally is severe. People with Down syndrome are also much more likely to die from infections if left untreated.
The NIH's National Institute of Child Health and Human Development convened a working group of NIH scientists. Through a public comment process, the scientists listened to comments and suggestions from families of individuals with Down Syndrome, as well as from Down Syndrome research advocacy organizations. The NIH scientists then developed the research plan in collaboration with researchers in the national scientific community.
Among the research objectives identified as priorities over the next 10 years is the need for greater access to laboratory animals with the characteristics of Down syndrome.
The plan cites the need for increased research on the medical, cognitive, and behavioral conditions that occur in people with Down syndrome. These conditions include leukemia, heart disease, sleep apnea, seizure disorders, stomach disorders and mental health problems.
The working group also identified the need to study whether aging has a greater impact on mental processes in people with Down syndrome than in people who do not have Down syndrome. As adults, individuals with Down syndrome age prematurely and may experience dementia, memory loss or impaired judgment similar to that experienced by Alzheimer's disease patients.
The plan summarizes current research efforts by the various NIH institutes studying Down syndrome.
The National Institute of Child and Human Development (NICHD) has supported Down syndrome research since the institute was established in the 1960s. NICHD scientists have bred mice that help researchers study the intellectual disability and dementia that occurs in Down syndrome.
The NICHD is currently studying specific genes and gene groups that may play a role in developing Down syndrome. Researchers are also studying the role that the age of the mother's egg plays in developing the disorder.
An NICHD-sponsored study is examining whether individuals with an additional complete copy of chromosome 21 differ as they age from people with only a portion of the extra chromosome.
Another long-term study will examine the prevalence of dementia in adults with Down syndrome and whether certain medications, like hormone replacement therapy, slow the aging process in Down syndrome.
Other NICHD-supported projects include devising a weight loss program for adults with developmental disabilities, and a computer program to help children with Down syndrome learn.
The National Heart, Lung, and Blood Institute (NHLBI) is supporting studies of the genes that contribute to heart malformations found in Down syndrome patients. The NHLBI also is supporting investigations of the causes and potential treatments for obstructive sleep apnea, a disorder in which throat tissue blocks the airway during sleep, temporarily shutting off air to the lungs. Obstructive sleep apnea is common in Down syndrome children.
Children with Down syndrome are 10 to 15 times more likely than other children to develop leukemia. The National Cancer Institute is investigating various types of leukemia that affect children with Down syndrome.
Other NIH institutes continue to investigate additional aspects of Down syndrome. The National Institute on Aging is conducting research on ways to treat Alzheimer's disease in people with Down syndrome.
The National Institute of Allergy and Infectious Diseases is studying the significance of two genes recently found in a region of chromosome 21. These genes are involved in the development of the immune response against disease.
The National Institute of Mental Health is investigating rates and possible treatments for mental disorders found with Down syndrome. These include autism, obsessive-compulsive disorder, depression, and psychosis.
The National Institute of Neurological Disorders and Stroke (NINDS) is investigating how the brain is affected by Down syndrome. The intellectual disability seen in people with Down syndrome is caused when neurons die or do not function properly.
One NINDS study is investigating the potential role of a specific gene called APP, for amyloid precursor protein. It is thought that disruption of the APP gene may kill neurons by interfering with a growth factor needed for neurons to survive. APP is believed to be related to Alzheimer's disease and may play a role in Down syndrome.
The research plan on Down syndrome "is intended to provide the NIH, and its member Institutes and Centers, with guidelines for prioritizing and coordinating future research related to Down syndrome," wrote the members of the NIH Down syndrome working group in the report.