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Down syndrome

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Related Terms
  • Behavioral therapy, chromosomal disorder, chromosome 21, cognitive disabilities, dementia, Down's syndrome, Downs syndrome, heart defects, inherited disorder, intervention programs, leukemia, physical therapy, occupational therapy, speech-language therapy, translocation.

Background
  • Down syndrome, also called Down's syndrome or Downs syndrome, is a genetic disorder that is characterized by distinct physical characteristics and varying degrees of cognitive dysfunction that range from mild to severe. Cognitive disabilities occur when a person has difficulty thinking, processing, and storing information in order to solve problems. Some individuals may live independently as adults, while others may require long-term care and support.
  • Even though Down syndrome is a genetic condition, it is not usually inherited from parents. Most cases occur spontaneously before or during conception. One of the biggest risk factors of Down syndrome is the mother's age when she conceives. Females who are 35 years and older are most likely to have abnormal eggs that may lead to Down syndrome. However, because most women have children before this age, it is not considered the leading cause of the disorder.
  • Researchers estimate that about 6,000 babies are born with Down syndrome each year in the United States. Gender, race, and ethnicity do not appear to play a role in the development of the disorder.
  • In 1929, many children born with Down syndrome did not live to be older than 10 years of age. This is because patients with Down syndrome have an increased risk of developing heart defects, leukemia, infectious diseases, and other potentially life-threatening conditions.
  • Today, however, patients can expect to live to be 50 years of age or older, depending on the severity of related health problems. Although there is no cure for Down syndrome, early treatment has been shown to increase patients' long-term prognoses. Early intervention and proper care has also been shown to help Down syndrome patients develop into independent adults.

Diagnosis
  • General: In the past, prenatal screening for Down syndrome was offered to older mothers who were at high risk of having a baby with the disorder. Today, the American College of Obstetricians and Gynecologists recommends offering Down syndrome screening as part of prenatal testing for pregnant women of all ages. If screening tests indicate that a mother is at high risk of having a baby with Down syndrome, prenatal diagnostic tests may be performed. However, because diagnostic tests may lead to complications during pregnancy, pregnant mothers should discuss the potential risks and benefits of screening before making any decisions.
  • Screening tests during pregnancy:
  • There are many tests that can be performed during pregnancy to determine if a mother has a high risk of having a baby with Down syndrome. The most effective screening includes an ultrasound and blood tests, which are performed between the 11th and 14th week of pregnancy. These tests can help determine if a mother is at risk of having a baby with Down syndrome, spina bifida (a condition that occurs when the tissues surrounding the spinal cord do not develop properly), or other types of chromosomal disorders. These tests only indicate if there is a risk of Down syndrome. They cannot diagnose the disorder. Some women may be at risk of having babies with Down syndrome but give birth to healthy babies.
  • Ultrasound: During an ultrasound, a wand-like device is rubbed against the mother's stomach. Ultrasounds use high-energy sound waves (ultrasound) that bounce off internal tissues or organs to produce images of the fetus. During the ultrasound, a doctor performs a test, called the nuchal translucency screening test. The doctor measures the clear (translucent) space in the tissue at the back of the fetus' neck. The fetus may be at risk of having Down syndrome if the clear space is larger than normal. This is because fluid often collects inside this tissue if abnormalities are present.
  • Blood tests: Blood tests are also performed in combination with an ultrasound. Blood tests measure the amount of pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin (HCG). If the mother has low levels of PAPP-A and HCG, it may suggest a problem with the baby.
  • If these tests indicate that there is a risk of Down syndrome, diagnostic tests, such as amniocentesis or chorionic villus sampling, may be recommended. These diagnostic tests can definitively determine if the fetus has Down syndrome.
  • Diagnostic tests during pregnancy:
  • Individuals at high risk of having of having babies with Down syndrome may choose to undergo diagnostic tests during pregnancy. Each of these tests can diagnose Down syndrome with 98-99% accuracy. However, there are serious risks associated with these tests.
  • Amniocentesis: During amniocentesis, a long, thin needle is inserted into the abdominal wall to the uterus and a small amount of amniotic fluid is removed from the sac surrounding the fetus. The fluid is then analyzed for an extra chromosome 21. This test is performed after 15 weeks of gestation. The risk of miscarriage ranges from one out of 200-400 patients. Some patients may experience minor complications, such as cramping, leaking fluid, or irritation where the needle was inserted.
  • Chorionic villus sampling (CVS): During chorionic villus sampling (CVS), a small piece of tissue (chorionic villi) is removed from the placenta during early pregnancy. Depending on where the placenta is located, CVS can be performed through the cervix (transcervical) or through the abdomen (transabdominal). The tissue sample is then analyzed for the presence of an extra chromosome 21. This procedure may be performed between the ninth and 14th week of gestation. The risks of infection or fetal damage are slightly higher than the risks of amniocentesis. Miscarriage occurs in about two percent of women who undergo this procedure.
  • Percutaneous umbilical blood sampling (PUBS): Percutaneous umbilical blood sampling (PUBS) may also be performed. During the procedure, a small sample of blood is taken from a vein in the umbilical cord. The sample is then analyzed for the presence of an extra chromosome 21. This test is usually performed after 18 weeks of gestation. This test poses a greater risk of miscarriage than both amniocentesis and CVS. It is usually only performed when a prompt diagnosis is needed.
  • Diagnostic tests for newborns:
  • After birth, Down syndrome may be diagnosed based on the infant's physical appearance. In order to confirm a diagnosis, a doctor usually orders a chromosomal karyotype test, which provides a picture of the person's chromosomes. A sample of the patient's blood is taken and analyzed for the presence of an extra chromosome 21.

Complications
  • General: Patients should regularly visit their doctors in order to treat and help prevent complications of Down syndrome. Patients typically live to be 50 years of age or older, depending on the severity of health-related problems.
  • Heart defects: About 50% of Down syndrome patients are born with heart defects, which range from mild to life-threatening. Some infants may need to undergo surgery to correct structural problems of the heart. Some of the most common heart abnormalities include endocardial cushion defect, ventricular septal defect, secundum arterial septal defect, tetralogy of Fallot, and isolated patent arteriosus. These defects occur when parts of the heart, such as the walls, chambers, or valves, do not develop properly.
  • Leukemia: Down syndrome patients are born with impaired cellular immunity. Therefore, children with Down syndrome have an increased risk of developing a type of cancer called leukemia. Researchers estimate that children and adolescents with Down are 10-30% more likely to develop leukemia than the general population.
  • Infectious diseases: Patients with Down syndrome generally have abnormal immune systems, making them more susceptible to infections and diseases. Pneumonia is one of the most common infections to affect Down syndrome patients.
  • Dementia: Adults with Down syndrome are more likely to develop dementia than people who do not have the syndrome. Dementia symptoms often develop before the age of 40. Dementia is the loss of mental ability that is so severe that it interferes with daily functioning.
  • Other problems: Down syndrome has also been associated with many other health problems, including gastrointestinal blockage, thyroid problems, hearing loss, dental problems, and poor vision.

Treatment
  • General: Currently, there is no cure for Down syndrome. However, many treatments and therapies may help patients cope with the disorder. With proper therapy, some patients are able to live independently once they become adults, while others may need lifelong support and/or residential care. Adults with profound intellectual disabilities usually require lifelong nursing care.
  • Down syndrome patients typically visit several doctors, including a gastroenterologist, cardiologist, developmental pediatrician, and other specialists to monitor their conditions and treat complications of Down syndrome throughout life.
  • Occupational therapy: Patients may benefit from occupational therapy. During sessions, a therapist helps the child learn skills to help him/her perform basic daily tasks, such as feeding, dressing, and communicating with others. Some patients work with therapists who specialize in disorders and disabilities, including Down syndrome. Parents and caregivers can ask their children's pediatricians for recommended therapists.
  • Education: Patients with Down syndrome must have access to education that is tailored to their specific strengths and weaknesses. According to the Individuals with Disabilities Education Act, all children with disabilities, including Down syndrome, must receive free and appropriate education. According to the law, members of the patient's school should consult with the patient's parents or caregivers to design and write an individualized education plan. Once all parties agree with the plan, the educational program should be started. The school faculty should document the child's progress in order to ensure that the child's needs are being met.
  • Educational programs vary among patients. In general, most experts believe that children with disabilities, including Down syndrome, should be educated alongside their non-disabled peers. The idea is that non-disabled students will help the patient learn appropriate behavioral, social, and language skills. Therefore, some Down syndrome patients are educated in mainstream classrooms. Other Down syndrome patients attend public schools but take special education classes. Others attend specialized schools that are designed to teach children with disabilities.
  • Early intervention programs: Patients with Down syndrome usually meet traditional developmental milestones. However, it typically takes them longer than most children to develop these skills. For instance, it may take a child with Down syndrome twice as long to crawl or walk than a healthy child. Therefore, caregivers should ask the doctors of Down syndrome patients about early intervention programs. These specialized programs expose Down syndrome children to appropriate sensory, motor, and cognitive activities. These programs typically involve special educators and therapists who help babies and young children develop their language, social, motor, and self-help skills.
  • Behavioral therapy: Behavioral therapy may also be beneficial. Several different types of behavioral therapy are available to help Down syndrome patients improve their communication and social skills, as well as their learning abilities and adaptive behaviors. Evidence suggests that behavioral therapy is most effective if it is started early in life, when the patient is three to four years old or younger.
  • Physical therapy: Physical therapy may help patients improve their physical strength and motor coordination. For example, since babies with Down syndrome usually have muscle tone, a physical therapist may be able to help babies learn how to roll over, sit up, and walk. A variety of techniques, including exercises, stretches, traction, electrical stimulation, and massage, are used during physical therapy sessions.
  • Speech-language therapy: Some patients with Down syndrome may benefit from speech-language therapy because individuals often develop communication skills slower than normal. During speech-language therapy, a qualified speech-language professional (SLP) works with the patient on a one-to-one basis, in a small group, or directly in a classroom, to help the patient improve speech, language, and communication skills. Programs are tailored to the patient's individual needs.
  • Speech pathologists use a variety of exercises to improve the patient's communication skills. Exercises typically start off simple and become more complex as therapy continues. For instance, the therapist may ask the patient to name objects, tell stories, or explain the purpose of an object.
  • On average, patients receive five or more hours of therapy per week for three months to several years. Doctors typically recommend that treatment is started early to ensure the best possible prognosis for the child.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
  1. Dykens EM. Psychiatric and behavioral disorders in persons with Down syndrome. Ment Retard Dev Disabil Res Rev. 2007;13(3):272-8.
  2. Esbensen AJ, Seltzer MM, Greenberg JS.Factors predicting mortality in midlife adults with and without Down syndrome living with family. J Intellect Disabil Res. 2007 Dec;51(Pt 12):1039-50.
  3. Fidler DJ, Nadel L. Education and children with Down syndrome: Neuroscience, development, and intervention. Ment Retard Dev Disabil Res Rev. 2007;13(3):262-71.
  4. Horbelt CV. Down syndrome: a review of common physical and oral characteristics. Gen Dent. 2007 Sep-Oct;55(5):399-402.
  5. March of Dimes Birth Defects Foundation. .
  6. National Down Syndrome Society. .
  7. National Institute of Child Health and Human Development. .
  8. Natural Standard: The Authority on Integrative Medicine. . Copyright © 2010.
  9. Sherman SL, Allen EG, Bean LH, et al. Epidemiology of Down syndrome. Ment Retard Dev Disabil Res Rev. 2007;13(3):221-7.

Causes
  • General: Although Down syndrome is considered a genetic disease, most cases are not inherited. Instead, the disorder is usually caused by a spontaneous mutation, or mistake, during the development of the egg, sperm, or embryo.
  • In healthy individuals, cells contain 23 pairs of chromosomes. These chromosomes contain the building blocks of life called DNA (deoxyribonucleic acid). Each pair of chromosomes contains one chromosome from each parent. A patient with Down syndrome has an extra 21st chromosome. There are three possible ways this can happen.
  • Trisomy 21: More than 90% of Down syndrome cases are caused by trisomy 21. This happens when a sperm or egg cell does not divide properly. As a result, the child is born with three copies of chromosome 21, instead of just two.
  • Translocation Down syndrome: In about four percent of cases, Down syndrome develops when a copy of chromosome 21 attaches, or translocates, onto another chromosome. This can happen before or during conception. Individuals with translocation have two normal copies of chromosomes 21 and a third copy that is translocated.
  • This is the only type of Down syndrome that can be inherited, or passed down from parents to their children. When it is inherited, a mother or father does not have extra chromosomes. Instead, the chromosomes are arranged abnormally. However, the parent's sperm or egg cells will contain the translocated chromosome as well as a normal chromosome 21. When these two chromosomes (one normal and one translocated) combine with the other parent's egg or sperm to form an embryo, a total of three chromosome 21 are present.
  • Although a parent can pass the condition onto his/her children, the parent does not experience symptoms of Down syndrome. Only about 50% of translocation Down syndrome cases are inherited. The other half occur spontaneously.
  • Mosaic Down syndrome: In rare cases, only some of a person's cells have extra copies of chromosome 21. This condition, called mosaic Down syndrome, is usually the result of abnormal cell division after fertilization. Patients with mosaic Down syndrome tend to have higher intellectual quotients (IQs) than people with other types of Down syndrome.

Risk factors
  • Maternal age: As women age, there is a greater chance that the cells in her eggs will not divide properly. This increases the risk of having a child with Down syndrome. Women who are 35 years old have a one out of 385 chance that their children will have Down syndrome. Forty-year-old women have a one out of 106 chance of giving birth to children with Down syndrome. By age 45, the risk increases to one out of 30.
  • Mothers of Down syndrome children: In general, a woman who has one child with Down syndrome has a one percent chance of having another child with the condition.
  • Genetic carriers: Carriers of rearranged chromosome 21 may pass translocation Down syndrome onto their children. The risk of passing the translocation onto a child depends on the parent's gender. Fathers who carry the translocated chromosome have a three percent risk of having children with Down syndrome. Mothers who carry the translocated chromosome have a 12% chance of having children with Down syndrome.

Tips for caregivers
  • Caregivers should find a team of trusted healthcare professionals. Patients with Down syndrome typically visit several specialized healthcare providers and professionals in order to properly treat and prevent complications associated with the disorder.
  • Caregivers may find support from other families who are caring for a patient with Down syndrome. Many communities have local support groups for parents, family members, and caregivers of patients.
  • Caregivers should educate themselves about Down syndrome. The more a caregiver knows about the condition, the better he/she can help the patient. Being educated on the disorder may also help the caregiver learn how to communicate better with the patient.
  • Parents of children with Down syndrome should stay in close contact with their children's teachers. This helps ensure that the child is receiving appropriate education that is tailored to his/her specific needs. Parents are also encouraged to find out how they can support their children's learning needs at home.

Copyright © 2011 Natural Standard (www.naturalstandard.com)

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.