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Walter T Little

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What is Down syndrome?
by Walter T Little   
Rated "G" by the Author.
Last edited: Saturday, January 14, 2012
Posted: Wednesday, January 11, 2012

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Article discussing Down syndrome, its cause, and treatment.

by Walter Little, Jr.


Down syndrome, or Down's syndrome (primarily in the United Kingdom) trisomy 21 is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named for John Langdon Down, a British physician who first described the syndrome in 1866. The condition was identified as chromosome 21 trisomy by Jerome Lejeune 1959.

As noted above, it is a chromosomal condition resulting from the presence of an extra copy of genetic material on the 21st chromosome – either in whole (trisomy 21) or part (such as due to translocation[1]). The effects and extent of the extra copy vary greatly from person to person, depending on genetic history, and pure chance. The occurrence of Down syndrome is estimated at one (1) per 733 births, however, it is statistically more common with older parents (both mothers and fathers) due to increased mutagen exposures upon reproductive cells. Down syndrome occurs in all human populations and analogous effects have also been found in other species such as chimpanzees[2] and mice.

Often Down syndrome is associated with some impairment of cognitive ability and physical growth, and a particular set of facial characteristics. Individuals with Down syndrome tend to have lower-than-average cognitive ability, often ranging from a mild to moderate disability. Many children with Down syndrome who received family support, enrichment therapies, and tutoring have been known to graduate from both high school and college and secure gainful employment.

Early childhood intervention including screening for common problems, medical treatment (where indicated), a conducive family environment, and vocational training have been shown to improve the overall development of a child with Down syndrome. Additionally, education and proper care go a long way toward improving the child's quality of life despite the genetic limitations caused by Down syndrome.

What are the signs and symptoms of Down syndrome?

Down syndrome can result from several different genetic mechanisms. This results in a wide variability of individual signs and symptoms due to a combination of complex genetic and environmental interactions. Because of these factors, prior to birth it is not possible to predict the symptoms that an individual with Down syndrome will develop.

Individuals with Down syndrome may have some – or all – of the following physical characteristics: 1) abnormally small chin (microgenia); 2) oblique eye fissures with epicanthic skin folds on the inner corner of the eyes (formerly known as mongoloid fold); 3) muscle hypotonia (poor muscle tone); 4) flat nasal bridge; 5) protruding tongue (due to small oral cavity and an enlarged tongue near the tonsils); 6) white spots on the iris (Brushfield spots); and 7) excessive joint laxity – including atlanto-axial instability. In addition to physical disabilities, people with Down syndrome also have intellectual disability ranging from mild (IQ 50 – 70) to moderate (IQ 35 – 50), however, individuals with Mosaic Down syndrome tend to have an IQ which is 10 to 30 points higher. They might also have a broad head and a very round face.

Language skills – of a person with Down syndrome – show a difference between understanding speech and expressing speech, and it is not unusual for them to have a speech delay[3]. Fine motor skills are also delayed and often lag behind gross motor skills, which can interfere with cognitive development. The effects of Down syndrome on the development of gross motor skills can be quite variable. For example, some children will begin walking at around two (2) years of age, while others might not start walking until the age of four (4). The use of physical therapy and/or participation in a program of adapted physical education (APE) can promote enhanced development of gross motor skills in children with Down syndrome.

Growth parameters such as height, weight, and head circumference are smaller in children with Down syndrome than with typical individuals of the same age. Adults tend to have short stature with the average height for men being 5 feet 1 inch (157 cm) and, for women, 4 feet 9 inches (144 cm). Generally, persons with Down syndrome are at increased risk for obesity as they age.


Are there complications from Down syndrome?

Individuals with Down syndrome are at a higher risk for many conditions. The medical consequences of the extra genetic material in Down syndrome are highly variable and can affect the function of any organ system or bodily process. Some of these are present at birth, such as certain heart malformations; others become apparent over time, such as epilepsy.

Congenital heart disease

The incidence of congenital heart disease in children with Down syndrome (DS) can be as high as fifty percent (50%). An atrioventricular septal defect known as endocardial cushion defect is the most common form affecting up to forty percent (40%) of patients with DS.


Thyroid disorders

Individuals with DS are at an increased risk for dysfunction of the thyroid gland (pictured at left) – an organ that helps control metabolism.  Low thyroid (hypothyroidism) is most common, occurring in almost one-third (1/3) of those with DS. One explanation for this is due to the absence of the thyroid at birth (congenital hypothyroidism) or due to attack on the thyroid by the immune system.

Gastrointestinal disorders

Down syndrome increases the risk of Hirschsprung's disease – a condition where the nerve cells that control the function of portions of the colon are not present. This results in severe constipation. Other common GI anomalies include: duodenal atresia, annular pancreas, and imperforate anus.


There is infertility among both males and females with Down syndrome; males are usually (emphasis added) unable to father children, while females demonstrate significantly lower rates of contraception relative to persons not affected by DS. Women are also less fertile and have difficulties with miscarriage, premature birth, and difficult labor.


Both children and adults with DS are at increased risk for developing epilepsy. The risk for Alzheimer's disease is also higher in individuals with DS – estimates are that anywhere between ten percent (10%) and twenty-five percent (25%) of individuals with Down syndrome show signs of Alzheimer's before age fifty (50). This sharp increase in both the incidence and prevalence of dementia may be one factor that drives the decreased life expectancy of persons with Down syndrome.

 Ophthalmology and otolaryngology

Eye disorders are more common in people with DS. It's estimated that almost half of the people with DS also have strabismus where their eyes don't move in tandem. Refractive errors – which require glasses or contact lenses for correction – are also more common. Persons with DS may also experience Brushfield spots where they have small white or grayish/brown spots on the periphery of the iris.


Is there screening to detect Down syndrome?

The answer is yes. Pregnant women can be screened for various complications during pregnancy and many of these tests can discover DS. Genetic counseling along with tests such as amniocentesis, chorionic villus sampling (CVS) (pictured at left) or percutaneous umbilical cord blood sampling (PUBS) are usually offered to families who are likely to have increased chance of having a child with Down syndrome, or in cases where normal prenatal exams indicate possible problems. American College of Obstetricians and Gynecologists (ACOG) guidelines recommend that non-invasive screening and invasive testing be offered to all women, regardless of age, and most likely all physicians currently follow these guidelines. However, some insurance plans will only reimburse invasive testing if a woman is more than thirty-four (34) years old or if she has received a high-risk score from a non-invasive screening test.

CVS and amniocentesis are considered invasive procedures, in that they involve inserting instruments into the uterus, and therefore carry a small risk of causing fetal injury or miscarriage. The risks of miscarriage for CVS and amniocentesis are often quoted as one percent (1%) and one-half percent (0.5%) respectively. It should be noted, however, that there are also several common non-invasive screens that can also indicate whether or not a fetus has DS. These are normally performed either late in the first trimester or early in the second trimester.



(weeks gestation)

Detection rate

False positive rate


Quad screen

15 - 20



Test measures the maternal serum alpha feto protein (a fetal liver protein), estriol (a pregnancy hormone), human chorionic-gonadotropin (h Cg) (pregnancy hormone), and inhibin-Alpha (INHA).


Nuchal translucency/free beta/PAPPA screen

(aka “1st Trimester Combined Test”)

10 – 13.5



Uses ultrasound to measure Nuchal Translucency in addition to free-beta h Cg and PAPPA (pregnancy associated plasma protein A). NIH has confirmed that this first (1st) trimester test is more accurate  than second (2nd) trimester  methods. The performance an NT ultrasound requires considerable skill; a Combined test may be less accurate if there is operator error, resulting in lower-than-advertised sensitivity and higher false-positive rate.

Integrated Test

10 - 13.5 and

15 - 20



The Integrated test uses measurements from both the first (1st) Trimester Combined test and second (2nd) Trimester Combined Quad to yield a more accurate screening result. Because all of these test are dependent on accurate calculation of the gestational age of the fetus, the real world false-positive rate is greater than five percent (5%) and could be closer to seven percent (7%).


Even with the best non-invasive screens, the detection rate is between 90% and 95% and the rate of false positive is two percent (2%) to five percent (5%). Inaccuracies can be caused by undetected multiple births (very rare with ultrasound tests), incorrect date of pregnancy, or normal variation in proteins.

Confirmation of screen positive is normally accomplished with either amniocentesis or chorionic villus sampling (CVS). Amniocentesis is an invasive procedure that involves taking amniotic fluid from the amniotic sac and identifying fetal cells. The lab work can take several weeks but will detect over 99.8% of all numerical chromosomal problems with a very low false positive rate.


Termination of pregnancy and ethical concerns

A 2002 literature review of elective abortion rates found that between 91% to 93% of pregnancies in both the United Kingdom and Europe with a diagnosis of DS were terminated.  Data from the National Down Syndrome Cytogenetic Register in the United Kingdom showed that from 1989 until 2006, the proportion of women choosing to terminate a pregnancy following a prenatal diagnosis of Down syndrome has remained constant at around 92%.

Medical ethicist Ronald Green argues that parents have an obligation to avoid “genetic harm” to their offspring and Claire Rayner, then a patron of the Down Syndrome Association, defended testing and abortion saying “The hard facts are that it is costly in terms of human effort, compassion, energy, and finite resources such as money, to care for individuals with handicaps . . . people who are not yet parents should ask themselves if they have the right to inflict such burdens on others, however willing they are themselves to take their share of the burden in the beginning.

Some physicians and ethicist are concerned about the ethical ramifications of the high abortion rate for this condition. Conservative commentator George Will called it “eugenics by abortion”. British peer Lord Rix stated that “alas, the birth of a child with Down syndrome is still considered by many to be an utter tragedy,” and “the ghost of the biologist Sir Francis Galton who founded the eugenics movement in 1885, still stalks the corridors of many a teaching hospital”. Doctor David Mortimer has argued in Ethics and Medicine that “Down syndrome infants have long been disparaged by some doctors and government bean counters.” Some members of the disability rights movement “believe that public support for prenatal diagnosis and abortion based on disability contravenes the movement's basic philosophy and goals.”


Management of Down syndrome

The treatment of individuals with Down syndrome is dependent on the particular manifestations of the condition. For example, individuals with congenital heart disease may require major corrective surgery soon after birth. Other individuals may experience relatively minor health problems requiring no intervention.

Examination at birth

Initial examination of newborns with Down syndrome should pay particular attention to certain physical signs that are more prevalent with DS. Evaluation of the red reflex can help to identify congenital cataracts. Movement of the eyes should be observed to identify strabismus. The occurrence of constipation should raise concerns for the occurrence of Hirschsprung disease. Likewise, feeding problems should prompt intense education to ensure adequate input and nutrition.

At birth, an ultrasound of the heart (echo-cardiogram – pictured at right) should be done immediately in order to identify congenital heart disease. A complete blood count (CBC) should be conducted to check for pre-existing leukemia. Additionally, a hearing test using brain stem auditory evoked responses (BAERS) should be performed to identify and characterize any hearing deficits.

The American Academy of Pediatrics – among other health organizations – has issued a series of recommendations regarding the screening of individuals with DS for particular diseases.

Plastic surgery

Plastic surgery has sometimes been advocated and performed on children with Down syndrome, based on the assumption that such surgery can reduce the facial features associated with DS and, thereby, decreasing social stigma and leading to a better quality of life. Researchers say, however, they are unable to verify this: “. . .although most patients reported improvements in their child's speech and appearance, independent raters could not readily discern improvement . . .” For a partial glossectomy (tongue reduction – pictured at left) one researcher found that one (1) out of three (3) patients “achieved oral competence,” while two (2) out of three (3) showed speech improvement. Stated Dr. Len Leshin “Despite being in use for over twenty (20) years, there is still not a lot of solid evidence in favor of the use of plastic surgery in children with Down syndrome.”

Cognitive development

The identification of the best methods of teaching each particular child begins ideally soon after birth and continues through the early intervention program (EIP)[4].  Cognitive development in with DS is quite variable. Currently, it’s not possible at birth to predict the capabilities of any individual reliably, nor is the number or appearance of physical features predictive of future ability. Since children with DS have a wide range of abilities, success at school can vary greatly, which underlines the importance of evaluating children individually. The cognitive problems, which are found among children with DS, can also be found among other children without the condition.

Individuals with Down syndrome differ considerably in both their language and communications skills. It is routine to screen for both middle ear problems and hearing loss; in the event of the latter, low-gain hearing aids or other amplification devices can be useful for learning language. Early communication intervention also fosters linguistic skills. Completion of a language assessment can help to profile strengths and weaknesses; for example, it’s common for receptive language skills to exceed expressive skills. Individualized speech therapy can target specific literacy. Augmentative and alternative communication (AAC) methods, such as pointing, body language, objects, or graphics are often used to aid communications.

In education, the mainstreaming of children with DS is becoming less controversial in many countries. 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 DS, so over time the intellectual and emotional gap between children with DS and without DS may widen. Complex thinking as required in science as well as history, the arts, and other subjects can often be beyond the abilities of some, or achieved much later than in other children. Based on these facts, children with DS may benefit from mainstreaming provided that some adjustments are made to the curriculum.

Some European countries – such as Germany and Denmark – advocate a two-teacher system, where the second teacher takes over a group of children with disabilities within the class. A popular alternative to this method is cooperation between special needs schools and mainstream schools. Using this method, the core subjects are taught in a separate class, which neither slows down the typical students, nor neglects children with disabilities. Social activities, outings, and arts activities are performed together as are breaks and meals.

Childhood and adulthood follow-up

As children with DS grow, their progress should be plotted on a growth chart in order to detect deviations from expected growth. As pictured at left, special growth charts are available so that children with Down syndrome can be compared with other children who also have DS. In addition to charting growth, thyroid function tests should be performed at six (6) months and one (1) year of age and then yearly thereafter. Examination of the ears for infection – as well as objective hearing tests – should be performed at each doctor’s visit. Formal evaluation for refractive errors that require glasses should be conducted every two (2) years with subjective vision assessments performed during each visit. After age three (3), an x-ray of the child’s neck should be performed to screen for atlanto-axial instability.


What is the prognosis for Down syndrome?

The factors noted above can contribute to a shorter life expectancy for people with Down syndrome. One study carried out in the United States in 2002, showed an average lifespan of forty-nine (49) years with considerable variations between ethnic and socio-economic groups. However, in recent decades, the life expectancy of people with DS has increased significantly up from twenty-five (25) years in 1980. The causes of death have also changed, with chronic neuro-degenerative diseases becoming more common as the population ages.

[1]    In genetics, a translocation is a chromosome abnormality caused by rearrangement of parts between non-homologous chromosomes.


[2]    McClure, H.M.; Belden, K.H.; et. al (1969) “Autosomal trisomy in a chimpanzee: resemblance to Down syndrome”, Science, pp. 1010 - 1012

[3]    Bird, G.; Thomas, S. (2002) “Providing effective speech and language therapy for children with Down syndrome in settings: A case example”, Down Syndrome News and Update, pp. 30-31

[4] An Early Intervention Program (EIP) is a program designed to promote the growth and development of  infants and toddlers who have a  developmental disability or delay involving one (1) or more areas. These can affect a child’s speech, physical ability, or social skills.


Source: Rhode Island Department of Health  (




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