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About Down Syndrome

Down syndrome (DS), also called Trisomy 21, is a condition in which extra genetic material causes delays in the

way a child develops, both mentally and physically. It affects about 1 in every 800 babies born in the United

States.

The physical features and medical problems associated with Down syndrome can vary widely from child to child.

While some kids with DS need a lot of medical attention, others lead healthy lives.

Though Down syndrome can't be prevented, it can be detected before a child is born. The health problems that

may go along with DS can be treated, and many resources are available to help kids and their families who are

living with the condition.

What Causes It?

Normally, at the time of conception a baby inherits genetic information from its parents in the form of 46

chromosomes: 23 from the mother and 23 from the father. In most cases of Down syndrome, a child gets an extra

chromosome 21 — for a total of 47 chromosomes instead of 46. It's this extra genetic material that causes the

physical features and developmental delays associated with DS.

Although no one knows for sure why DS occurs and there's no way to prevent the chromosomal error that causes

it, scientists do know that women age 35 and older have a significantly higher risk of having a child with the

condition. At age 30, for example, a woman has about a 1 in 1,000 chance of conceiving a child with DS. Those

odds increase to about 1 in 400 by age 35. By 40 the risk rises to about 1 in 100.

How Down Syndrome Affects Kids

Kids with Down syndrome tend to share certain physical features such as a flat facial profile, an upward slant to

the eyes, small ears, and a protruding tongue.

Low muscle tone (called hypotonia) is also characteristic of children with DS, and babies in particular may seem

especially "floppy." Though this can and often does improve over time, most children with DS typically reach

developmental milestones — like sitting up, crawling, and walking — later than other kids.

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At birth, kids with DS are usually of average size, but they tend to grow at a slower rate and remain smaller than

their peers. For infants, low muscle tone may contribute to sucking and feeding problems, as well as constipation

and other digestive issues. Toddlers and older kids may have delays in speech and self-care skills like feeding,

dressing, and toilet teaching.

Down syndrome affects kids' ability to learn in different ways, but most have mild to moderate intellectual

impairment. Kids with DS can and do learn, and are capable of developing skills throughout their lives. They simply

reach goals at a different pace — which is why it's important not to compare a child with DS against typically

developing siblings or even other children with the condition.

Kids with DS have a wide range of abilities, and there's no way to tell at birth what they will be capable of as they

grow up.

Medical Problems Associated With DSWhile some kids with DS have no significant health problems, others may experience a host of medical issues that

require extra care. For example, almost half of all children born with DS will have a congenital heart defect.

Kids with Down syndrome are also at an increased risk of developing pulmonary hypertension, a serious condition

that can lead to irreversible damage to the lungs. All infants with Down syndrome should be evaluated by a

pediatric cardiologist.

Approximately half of all kids with DS also have problems with hearing and vision. Hearing loss can be related to

fluid buildup in the inner ear or to structural problems of the ear itself. Vision problems commonly include

strabismus (cross-eyed), near- or farsightedness, and an increased risk of cataracts.

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Regular evaluations by an otolaryngologist (ear, nose, and throat doctor), audiologist, and an ophthalmologist are

necessary to detect and correct any problems before they affect language and learning skills.

Other medical conditions that may occur more frequently in kids with DS include thyroid problems, intestinal

abnormalities, seizure disorders, respiratory problems, obesity, an increased susceptibility to infection, and a

higher risk of childhood leukemia. Upper neck abnormalities are sometimes found and should be evaluated by a

doctor (these can be detected by cervical spine X-rays). Fortunately, many of these conditions are treatable.

Prenatal Screening and Diagnosis

Two types of prenatal tests are used to detect Down syndrome in a fetus: screening tests and diagnostic tests.

Screening tests estimate the risk that a fetus has DS; diagnostic tests can tell whether the fetus actually has the

condition.

Screening tests are cost-effective and easy to perform. But because they can't give a definitive answer as to

whether a baby has DS, these tests are used to help parents decide whether to have more diagnostic tests.

Diagnostic tests are about 99% accurate in detecting Down syndrome and other chromosomal abnormalities.

However, because they're performed inside the uterus, they are associated with a risk of miscarriage and other

complications.

For this reason, invasive diagnostic testing previously was generally recommended only for women age 35 or older,

those with a family history of genetic defects, or those who've had an abnormal result on a screening test.

However, the American College of Obstetrics and Gynecology (ACOG) now recommends that all pregnant women

be offered screening with the option for invasive diagnostic testing for Down syndrome, regardless of age.

If you're unsure about which test, if any, is right for you, your doctor or a genetic counselor can help you sort

through the pros and cons of each.

Screening tests include:

• Nuchal translucency testing. This test, performed between 11 and 14 weeks of pregnancy, uses ultrasound

to measure the clear space in the folds of tissue behind a developing baby's neck. (Babies with DS and other

chromosomal abnormalities tend to accumulate fluid there, making the space appear larger.) This

measurement, taken together with the mother's age and the baby's gestational age, can be used to calculate

the odds that the baby has DS. Nuchal translucency testing is usually performed along with a maternal blood

test.

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•

• The triple screen or quadruple screen (also called themultiple marker test). These tests measure the

quantities of normal substances in the mother's blood. As the names imply, triple screen tests for three

markers; the quadruple screen includes one additional marker and is more accurate. These tests are typically

offered between 15 and 18 weeks of pregnancy.

• Integrated screen. This uses results from first-trimester screening tests (with or without nuchal translucency)

and blood tests with a second trimester quadruple screen to come up with the most accurate screening results.

• A genetic ultrasound. A detailed ultrasound is often performed at 18 to 20 weeks in conjunction with the

blood tests, and it checks the fetus for some of the physical traits abnormalities associated with Down

syndrome.

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Diagnostic tests include:

• Chorionic villus sampling (CVS). CVS involves taking a tiny sample of the placenta, either through the cervix

or through a needle inserted in the abdomen. The advantage of this test is that it can be performed during the

first trimester, typically between 10 and 12 weeks. The disadvantage is that it carries a slightly greater risk of 

miscarriage as compared with amniocentesis and has other complications.

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• Amniocentesis. This test, performed between 15 and 20 weeks of pregnancy, involves the removal of a small

amount of amniotic fluid through a needle inserted in the abdomen. The cells can then be analyzed for the

presence of chromosomal abnormalities. Amniocentesis carries a small risk of complications, such as preterm

labor and miscarriage.

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• Percutaneous umbilical blood sampling (PUBS). Usually performed after 18 weeks, this test uses a needle

to retrieve a small sample of blood from the umbilical cord. It carries risks similar to those associated with

amniocentesis.

After a baby is born, if the doctor suspects DS based on the infant's physical characteristics, a karyotype — a blood

or tissue sample stained to show chromosomes grouped by size, number, and shape — can be done to verify the

diagnosis.

Signs and symptoms

Neoteny

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Main article: neoteny 

The signs and symptoms of Down syndrome are characterized by the neotenization of the brain and body to the fetal state.[17] Down syndrome is characterized by decelerated maturation (neoteny), incomplete morphogenesis (vestigia)

and atavisms.[18] Dr. Weihs considers Down syndrome to be a condition of "neoteny" that makes people "like a baby." [19]

Down syndrome can result from several different genetic mechanisms. This results in a wide variability in individual due to

complex gene and environment interactions. Prior to birth, it is not possible to predict the symptoms that an individual with

Down syndrome will develop.

Physical characteristics

Feet of a boy with Down Syndrome

Individuals with Down syndrome may have some or all of the following physical characteristics:microgenia (abnormally small

chin),[4] oblique eye fissures with epicanthic skin folds on the inner corner of the eyes (formerly known as a mongoloid fold),[5]

[19] muscle hypotonia (poor muscle tone), a flat nasal bridge, a single palmar fold, a protruding tongue (due to small oral

cavity, and an enlarged tongue near the tonsils) or  macroglossia,[5][19] "face is flat and broad",[8] a short neck, white spots on

the iris known as Brushfield spots,[20]

 excessive joint laxity including atlanto-axialinstability, excessive space between largetoe and second toe, a single flexion furrow of the fifth finger, a higher number of ulnar loop dermatoglyphs and short fingers.[19]

Growth parameters such as height, weight, and head circumference are smaller in children with DS than with typical

individuals of the same age. Adults with DS tend to have short stature and bowed legs[19]—the average height for men is 5

feet 1 inch (154 cm) and for women is 4 feet 9 inches (144 cm). [21] Individuals with DS are also at increased risk for obesity

as they age[22] and tend to be "round in shape".[19]

Characteristics Percentage[23] Characteristics Percentage[23]

mental retardation 100% small teeth 60%

stunted growth 100% flattened nose 60%

atypical fingerprints 90% clinodactyly 52%

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separation of the abdominal muscles 80% umbilical hernia 51%

flexible ligaments 80% short neck 50%

hypotonia 80% shortened hands 50%

brachycephaly 75% congenital heart disease 45%

smaller genitalia 75% single transverse palmar crease 45%

eyelid crease 75% Macroglossia (larger tongue) 43%

shortened extremities 70% epicanthal fold 42%

oval palate 69% Strabismus 40%

low-set and rounded ear 60% Brushfield spots (iris) 35%

Mental characteristicsMost individuals with Down syndrome have intellectual disability in the mild (IQ 50–70) to moderate (IQ 35–50) range, [24] with

individuals having Mosaic Down syndrome typically 10–30 points higher.[25] The use of IQ tests for individuals with Down

syndrome has been criticised on the grounds that the educator's low expectations and the fact that IQ tests do not take into

account accompanying physical disabilities, such as hearing and vision impairment that would slow the test-taking

performance.[26] I

Language skills show a difference between understanding speech and expressing speech, and commonly individuals with

Down syndrome have a speech delay.[27] Fine motor skills are delayed[28] and often lag behind gross motor skills and can

interfere with cognitive development. Effects of the condition on the development of gross motor skills are quite variable.

Some children will begin walking at around 2 years of age, while others will not walk until age 4. Physical therapy, and/or 

participation in a program of adapted physical education (APE), may promote enhanced development of gross motor skills in

Down syndrome children.[29]

Management

Treatment of individuals with Down syndrome depends on the particular manifestations of the condition. For instance,

individuals with congenital heart disease may need to undergo major corrective surgery soon after birth. Other individuals

may have relatively minor health problems requiring no therapy.

Plastic surgery

Plastic surgery has sometimes been advocated and performed on children with Down syndrome, based on the assumption

that surgery can reduce the facial features associated with Down syndrome, therefore decreasing social stigma, and leading

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to a better quality of life.[91]Plastic surgery on children with Down syndrome is uncommon,[92] and continues to be

controversial. Researchers have found that for facial reconstruction, "...although most patients reported improvements in

their child's speech and appearance, independent raters could not readily discern improvement...."[93] For partial glossectomy

(tongue reduction), one researcher found that 1 out of 3 patients "achieved oral competence," with 2 out of 3 showing

speech improvement.[94] Len Leshin, physician and author of the ds-health website, has stated, "Despite being in use for 

over twenty years, there is still not a lot of solid evidence in favor of the use of plastic surgery in children with Down

syndrome."[95] The U.S. National Down Syndrome Society has issued a "Position Statement on Cosmetic Surgery for Children with Down Syndrome",[96] which states "The goal of inclusion and acceptance is mutual respect based on who we

are as individuals, not how we look."

Cognitive development

The identification of the best methods of teaching each particular child ideally begins soon after birth through early

intervention programs.[97]Cognitive development in children with Down syndrome is quite variable. It is not currently possible

at birth to predict the capabilities of any individual reliably, nor are the number or appearance of physical features predictive

of future ability. Since children with Down syndrome have a wide range of abilities, success at school can vary greatly, which

underlines the importance of evaluating children individually. The cognitive problems that are found among children with

Down syndrome can also be found among other children. Therefore, parents can use general programs that are offered

through the schools or other means.

Individuals with Down syndrome differ considerably in their language and communication skills. It is routine to screen for middle ear problems and hearing loss; low gain hearing aids or other amplification devices can be useful for language

learning. Early communication intervention fosters linguistic skills. Language assessments can help profile strengths and

weaknesses; for example, it is common for receptive language skills to exceed expressive skills. Individualized speech

therapy can target specific speech errors, increase speech intelligibility, and in some cases encourage advanced language

and literacy. Augmentative and alternative communication (AAC) methods, such as pointing, body language, objects, or 

graphics are often used to aid communication. Relatively little research has focused on the effectiveness of communications

intervention strategies.[98]

In education, mainstreaming of children with Down syndrome is becoming less controversial in many countries. For 

example, there is a presumption of mainstream in many parts of the UK. Mainstreaming is the process whereby students of 

differing abilities are placed in classes with their chronological peers. Children with Down syndrome may not age

emotionally/socially and intellectually at the same rates as children without Down syndrome, so over time the intellectual and

emotional gap between children with and without Down syndrome may widen. Complex thinking as required in sciences butalso in history, the arts, and other subjects can often be beyond the abilities of some, or achieved much later than in other 

children. Therefore, children with Down syndrome may benefit from mainstreaming provided that some adjustments are

made to the curriculum.[99]

Some European countries, such as Germany and Denmark, advise a two-teacher system, whereby the second teacher 

takes over a group of children with disabilities within the class. A popular alternative is cooperation between special

schools and mainstream schools. In cooperation, the core subjects are taught in separate classes, which neither slows down

the typical students nor neglects the students with disabilities. Social activities, outings, and many sports and arts activities

are performed together, as are all breaks and meals.[100]

Speech delay may require speech therapy to improve expressive language.[27]

Alternative treatment

See also: Alternative therapies for developmental and learning disabilities

The Institutes for the Achievement of Human Potential is a nonprofit organization that treats children who have, as the IAHP

terms it, "some form of brain injury," including children with Down syndrome. The approach of "Psychomotor Patterning" is

not proven,[101] and is consideredalternative medicine.

Some experimental work with memantine - a NMDA-dampener usually used for  Alzheimer’s - is being conducted by Alberto

Costa, a physician and neuroscientist at University of Colorado. [102]

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Chorionic villus sampling (CVS) is done between 11 and 12 weeks of pregnancy. It involves the collection a chorionic

villus cell sample from the placenta either through insertion of a needle in the abdominal wall or through a catheter in

the vagina. The chromosomes in CVS are analyzed for deviations.

For percutaneous umbilical blood sampling (PUB), fetal blood is taken from the umbilical cord using a needle inserted

through the abdominal wall. The blood sample is examined for chromosome abnormalities. It is usually performed

after week 18.

What about cognitive impairment in Down syndrome?

The most common condition associated with Down syndrome is cognitive impairment. Cognitive development is often

delayed, and all individuals with Down syndrome have mild to severe learning difficulties that last throughout their 

lives. How the extra chromosome 21 leads to cognitive impairment is not entirely clear. The average brain size of a

person with Down syndrome is small and scientists have found alterations in the structure and function of certain

brain areas such as the hippocampus and cerebellum. Particularly affected is the hippocampus, which is responsible

for learning and memory. Scientists are using human studies and animal models of Down syndrome to find out which

specific genes on the extra chromosome 21 lead to different aspects of cognitive impairment.

How do adolescents with Down syndrome develop?

Adolescents with Down syndrome undergo the same hormonal changes during pubertyas typically developing

children. Girls with Down syndrome have regular menstrual periods and should receive instructions on hygiene.

Although women with Down syndrome are not very fertile, they can become pregnant. Men with Down syndrome

have low sperm count, but in some cases have fathered children. Proper education regarding sexual development

and contraception is very important.

What should one expect for adults with Down syndrome?

Individuals with Down syndrome live longer than ever before. Due to full inclusion in society, many adults with Down

syndrome now live semi-independently, enjoy relationships, work, and contribute to their community.

Adults with Down syndrome also age faster than average. The older they become, the higher the risk of developing

hypothyroidism, late-onset seizures (tonic-clonic seizures in particular), memory loss, and dementia. By age 40, many

individuals with Down syndrome will show signs of dementia and early-onset Alzheimer's disease. By age 60, 50% to

70% of adults will develop Alzheimer's disease. Why individuals with Down syndrome age prematurely and why they

develop Alzheimer's disease is not entirely clear. At least one gene (the amyloid precursor protein) on chromosome

21 is thought to be involved in Alzheimer's disease. Since individuals with Down syndrome have three copies of this

gene, it is likely that this gene contributes to the increased occurrence of Alzheimer's disease in this population.

Detecting dementia and early signs of Alzheimer's disease is a challenge in individuals with Down syndrome who are

often already cognitively impaired. It is important for caregivers and doctors to be aware of changes in skills

necessary for independence.

Do individuals with Down syndrome work?

While some individuals with Down syndrome find suitable paid employment, many others are volunteers, or hold no

 job. Individuals with Down syndrome who wish to work should receive adequate training and support. This is not

always readily available in all communities at present. In addition, employers should be made more aware of the

benefits of employing someone with Down syndrome.

Where can I find clinical trials for Down syndrome?

Down Syndrome Clinical Trials

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Down Syndrome At A Glance

• Down syndrome is a genetic disorder and the most common cause of cognitive impairment.

• Individuals with Down syndrome have characteristic physical features that are widely recognized.

•

Down syndrome is associated with heart defects, gastrointestinal conditions, and other health issues.

• Individuals with Down syndrome are at a high risk for developing dementia and early-onset Alzheimer's disease.

• The only well known risk factor for conceiving a child with Down syndrome is advanced maternal age.

• Screening for and diagnosis of Down syndrome is possible before birth.

• Due to improved medical treatment and social inclusion, the average life span of an individual with Down

syndrome is now more than 55 years.

• Individuals with Down syndrome often live very healthy and productive lives.