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Down syndrome – Pictures, Test, Life Expectancy, Causes, Symptoms, Treatment

Updated on October 22, 2013

Down syndrome is a genetic condition that results in developmental delays, mental retardation for life and other issues. The severity of Down syndrome differs from one affected person to another and hence the adverse symptoms vary from moderate to severe.

Down syndrome is considered as the most common genetic form of learning defects in children. A better grasp of the condition and early intervention programs have helped both children and adult patients to effectively deal with the problems associated with Down syndrome.

Symptoms of Down syndrome

Children affected by Down syndrome elicit unique facial features. It may also be noted that not all affected infants experience the same distinct features. Some of the common facial characteristics include:

  • A smaller head

  • Flattened facial appearance

  • Short neck

  • Abnormally shaped ears

  • Eyes that slant upwards. This aspect should not be associated with the infant’s ethnicity

  • A tongue that juts out

Down syndrome affected children may also experience:

  • Short and broad hands, and presence of just one crease in the palm

  • Poor muscle tone

  • Increased flexibility

  • Comparatively short fingers

Children with Down syndrome may grow up to be of average size. However, their growth is slower than normal and they tend to be shorter than children of their age. Additionally, it takes twice the time for patients to achieve developmental milestones like crawling and sitting. Mental retardation with varying degrees of severity is also observed.

Causes of Down syndrome

Normally, human cells have twenty three pairs of chromosomes. One chromosome from each pair come from the mother, while the other is passed on by the father.

Down syndrome occurs when chromosome 21 undergoes any one of the 3 types of anomalous cell division. All the 3 forms of abnormal cell division lead to additional genetic matter in chromosome 21, which is what eventually results in the developmental issues and unusual facial features. The 3 types of genetic variations responsible for Down syndrome are as follows:

  • Trisomy 21: Down syndrome is caused by this genetic variation in over ninety percent of the cases. Children affected by trisomy 21 have 3 copies of chromosome 21 in place of the normal 2 copies, in all the cells. This abnormal cell division occurs during egg cell or sperm cell development.

  • Translocation Down syndrome: It occurs when a part of chromosome 21 gets translocated or attaches itself to some other chromosome, during or before conception. This type of Down syndrome is rare. Affected children have the normal 2 copies of chromosome 21; but they also have additional genetic matter from chromosome 21 that attaches itself to the translocated chromosome.

  • Mosaic Down syndrome: It is another uncommon form of Down syndrome and is identified by the presence of an additional chromosome 21 only in some cells of the body. This abnormal cell division occurs post fertilization.

Any type of environmental or behavioral factors are not known to cause Down syndrome. It may also be noted that a majority of Down syndrome cases are not hereditary. The anomalous cell division generally occurs during egg, sperm or embryo development.

The only type of Down syndrome that can be inherited is the translocation form. However, only around four percent of affected children suffer from this type of Down syndrome. Also, only about 50 percent of patients have the genetic defect passed on from the parents.The transfer of translation Down syndrome anomaly from the paternal side can occur in about 3 percent for the cases, while the risk ranges from 10 to 15 percent if the mother is the carrier of the genetic defect.

If you already have a child with Down syndrome and/or an advanced maternal age can also increase the vulnerability to giving birth to a child with Down syndrome.

Diagnosis of Down syndrome (Tests)

Screening tests for Down syndrome have now become a normal part of prenatal care, especially for expectant women over the age of 35 years. The varied screening tests are listed below.

The combined first trimester test carried out in 2 steps between the eleventh and thirteenth weeks of pregnancy include:

  • Blood tests: They are used to determine the levels of a hormone called human chorionic gonadotropin as well as pregnancy-associated plasma protein-A (PAPP-A).

  • Ultrasound: It involves a nuchal translucency screening test wherein the back of the baby’s neck is checked for presence of excess fluid.

Pregnant women can also go for full integrated testing that is performed in 2 parts during the first and second trimester. The combined results of the tests yield a lower false-positive rate as compared to the first trimester combined test.

  • Part one of the test is conducted during first trimester and includes blood test to determine “PAPP-A” and the nuchal translucency ultrasound test.

  • Part two conducted in second semester measures the levels of estriol, alpha fetoprotein, inhibin A and HCG in the blood.

It may be noted that only about five percent of the women have the chance of being identified as vulnerable to conceiving a child with Down syndrome; however the actual risk is even lower. In case the tests identify a risk, then more invasive screening procedures such as chorionic villus sampling, amniocentesis, analysis of circulating fetal DNA and percutaneous umbilical blood samplingare carried out.

If a newborn exhibits the features associated with Down syndrome, then the doctor will order a chromosomal karyotype test which checks for the presence of extra chromosomal material.

Treatment of Down syndrome

There is no cure for Down syndrome. Early intervention programs that help develop language, sensory, social, motor, self-help and cognitive skillscan help the child achieve the full potential of his/her restricted abilities and live a full life. Medical assistance from a team of specialists can take care of the varied health complications.

Life expectancy of Down syndrome patients

Advancements in the medical field and research have dramatically increased the life spans of individuals affected by Down syndrome. Affected babies rarely survived beyond the age of 10 years till only 8 decades ago. Currently, depending on the severity of the associated health complications, patients can expect to live for more than 50 years.

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