DOWN SYNDROME



Down Syndrome

What is Down Syndrome?
Down syndrome is set of mental and physical symptoms that result from having an extra copy of Chromosome 21. Normally, a fertilized egg has 23 pairs of chromosomes. In most people with Down syndrome, there is an extra copy of Chromosome 21 (also called trisomy 21 because there are three copies of this chromosome instead of two), which changes the body’s and brain’s normal development.
(For more information on chromosomes, see Cells 101.)
What are the signs and symptoms of Down syndrome?
Even though people with Down syndrome may have some physical and mental features in common, symptoms of Down syndrome can range from mild to severe. Usually, mental development and physical development are slower in people with Down syndrome than in those without the condition. Intellectual and Developmental Disabilities (IDDs) is a disability that causes limits on intellectual abilities and adaptive behaviors (conceptual, social, and practical skills people use to function in everyday lives). Most people with Down syndrome have IQs that fall in the mild to moderate range of IDDs. They may have delayed language development and slow motor development.
Some common physical signs of Down syndrome include:
  • Flat face with an upward slant to the eye, short neck, and abnormally shaped ears
  • Deep crease in the palm of the hand
  • White spots on the iris of the eye
  • Poor muscle tone, loose ligaments
  • Small hands and feet
There are a variety of other health conditions that are often seen in people who have Down syndrome, including:
  • Congenital heart disease
  • Hearing problems
  • Intestinal problems, such as blocked small bowel or esophagus
  • Celiac disease
  • Eye problems, such as cataracts
  • Thyroid dysfunctions
  • Skeletal problems
  • Dementia—similar to Alzheimer’s

What is the treatment for Down syndrome?
Down syndrome is not a condition that can be cured. However, early intervention can help many people with Down syndrome live productive lives well into adulthood. Children with Down syndrome can often benefit from speech therapy, occupational therapy, and exercises for gross and fine motor skills. They might also be helped by special education and attention at school. Many children can integrate well into regular classes at school. For more information about treatments for Down syndrome, visit one of the Web sites provided below or ask your health care provider.

Who is at risk for Down syndrome?
The chance of having a baby with Down syndrome increases as a woman gets older—from about 1 in 1,250 for a woman who gets pregnant at age 25, to about 1 in 100 for a woman who gets pregnant at age 40. But, most babies with Down syndrome are born to women under age 35 because more younger women have babies. Because the chances of having a baby with Down syndrome increase with the age of the mother, many health care providers recommend that women over age 35 have prenatal testing for the condition. Testing the baby before it is born to see if he or she is likely to have Down syndrome allows parents and families to prepare for the baby’s special needs.
Parents who have already had a baby with Down syndrome or who have abnormalities in their own chromosome 21 are also at higher risk for having a baby with Down Syndrome.
Once the baby is born, a blood test can confirm whether the baby has Down syndrome.

PATAU SYNDROME-TRISOMY 13

Trisomy 13

URL of this page: http://www.nlm.nih.gov/medlineplus/ency/article/001660.htm
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Trisomy 13 (also called Patau syndrome) is a genetic disorder in which a person has three copies of genetic material from chromosome 13, instead of the usual two copies. Rarely, the extra material may be attached to another chromosome (translocation).

Causes

Trisomy 13 occurs when extra DNA from chromosome 13 appears in some or all of the body's cells.
  • Trisomy 13 -- the presence of an extra (third) chromosome 13 in all of the cells.
  • Trisomy 13 mosaicism -- the presence of an extra chromosome 13 in some of the cells.
  • Partial trisomy -- the presence of a part of an extra chromosome 13 in the cells.
The extra material interferes with normal development.
Trisomy 13 occurs in about 1 out of every 10,000 newborns. Most cases are not passed down through families (inherited). Instead, the events that lead to Trisomy 13 occur in either the sperm or the egg that forms the fetus.

Symptoms

Exams and Tests

The infant may have a single umbilical artery at birth. There are often signs of congenital heart disease, such as:
Gastrointestinal x-rays or ultrasound may show rotation of the internal organs.
MRI or CT scans of the head may reveal a problem with the structure of the brain. The problem is called holoprosencephaly. It is the joining together of the two sides of the brain.
Chromosome studies show trisomy 13, trisomy 13 mosaicism, or partial trisomy.

Treatment

Treatment of children with Trisomy 13 is planned on a case-by-case basis. The type of treatment given depends on the patient's individual condition.

Support Groups

Support Organization for Trisomy 18, 13 and Related Disorders (SOFT) -- www.trisomy.org

Outlook (Prognosis)

The syndrome involves multiple abnormalities, many of which are not compatible with life. More than 80% of children with trisomy 13 die in the first month.

Possible Complications

Complications begin almost immediately. Most infants with Trisomy 13 have congenital heart disease.
Complications may include:
  • Breathing difficulty or lack of breathing (apnea)
  • Deafness
  • Feeding problems
  • Heart failure
  • Seizures
  • Vision problems

When to Contact a Medical Professional

Call for an appointment with your health care provider if you have had a child with Trisomy 13, and you plan to have another child. Genetic counseling can help families understand the condition, the risk of inheriting it, and how to care for the patient.

Prevention

Trisomy 13 can be diagnosed before birth by amniocentesis with chromosome studies of the amniotic cells.
Parents of infants with trisomy 13 that is caused by a translocation should have genetic testing and counseling, which may help them avoid having another child with the condition.

Alternative Names

Patau syndrome

Update Date: 8/11/2009

Updated by: Diana Chambers, MS, EdD, Certified Genetics Counselor (ABMG), Charter Member of the ABGC, University of Tennessee, Memphis. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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=Trisomy 13= On this page:
Reviewed January 2009
==What is trisomy 13?==
Trisomy 13, also called Patau syndrome, is a chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Individuals with trisomy 13 often have heart defects, brain or spinal cord abnormalities, very small or poorly developed eyes (microphthalmia), extra fingers and/or toes, an opening in the lip (a cleft lip) with or without an opening in the roof of the mouth (a cleft palate), and weak muscle tone (hypotonia). Due to the presence of several life-threatening medical problems, many infants with trisomy 13 die within their first days or weeks of life. Only five percent to 10 percent of children with this condition live past their first year.
==How common is trisomy 13?==
Trisomy 13 occurs in about 1 in 16,000 newborns. Although women of any age can have a child with trisomy 13, the chance of having a child with this condition increases as a woman gets older.
==What are the genetic changes related to trisomy 13?==
Most cases of trisomy 13 result from having three copies of chromosome 13 in each cell in the body instead of the usual two copies. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 13.
Trisomy 13 can also occur when part of chromosome 13 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) or very early in fetal development. Affected people have two normal copies of chromosome 13, plus an extra copy of chromosome 13 attached to another chromosome. In rare cases, only part of chromosome 13 is present in three copies. The physical signs and symptoms in these cases may be different than those found in full trisomy 13.
A small percentage of people with trisomy 13 have an extra copy of chromosome 13 in only some of the body's cells. In these people, the condition is called mosaic trisomy 13. The severity of mosaic trisomy 13 depends on the type and number of cells that have the extra chromosome. The physical features of mosaic trisomy 13 are often milder than those of full trisomy 13.
Read more about chromosome 13.
==Can trisomy 13 be inherited?==
Most cases of trisomy 13 are not inherited and result from random events during the formation of eggs and sperm in healthy parents. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 13. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each cell of the body.
Translocation trisomy 13 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome. These rearrangements are called balanced translocations because there is no extra material from chromosome 13. A person with a balanced translocation involving chromosome 13 has an increased chance of passing extra material from chromosome 13 to their children.
==Where can I find information about diagnosis, management, or treatment of trisomy 13?==
These resources address the diagnosis or management of trisomy 13 and may include treatment providers.
You might also find information on the diagnosis or management of trisomy 13 in Educational resources and Patient support.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
==Where can I find additional information about trisomy 13?==
You may find the following resources about trisomy 13 helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
  • This link leads to a site outside Genetics Home Reference.
    This link leads to a site outside Genetics Home Reference.
    - Linking patients to medical research
  • This link leads to a site outside Genetics Home Reference.
    This link leads to a site outside Genetics Home Reference.
    - Recent literature
==What other names do people use for trisomy 13?==
  • Bartholin-Patau syndrome
  • Complete trisomy 13 syndrome
  • Patau's syndrome
  • Patau syndrome
  • Trisomy 13 syndrome
See How are genetic conditions and genes named? in the Handbook.
==What if I still have specific questions about trisomy 13?==
Ask the Genetic and Rare Diseases Information
This link leads to a site outside Genetics Home Reference.
This link leads to a site outside Genetics Home Reference.
.

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
==What glossary definitions help with understanding trisomy 13?==
atypical ; cell ; cell division ; chromosome ; cleft palate ; egg ; hypotonia ; microphthalmia ; mosaic ; muscle tone ; nondisjunction ; palate ; rearrangement ; reproductive cells ; sign ; sperm ; symptom ; syndrome ; translocation ; trisomy
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (11 links)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

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