Introduction

Down Syndrome, otherwise known as Trisomy 21, is a genetic disease that affects many households across the world. Despite the fact many believe that the sole reason for having a child with Down Syndrome is due to the age of the mother, doctors have concluded that there is no specific reason to why this occurs. Women 35 years old-44years old hold a 1 in 110 chance that they will give birth to a child with Down Syndrome. Women 45 and older have a 1 in 35 chance of having a child with Down Syndrome.

 

What is Down Syndrome?

Down Syndrome is a genetic condition that is caused by three copies of chromosome 21 being present rather than the normal two copies (Down, 2005). This extra copy of chromosome 21 causes problems in the development of the growing baby. Women who are 35 years of age and older run a greater chance of having a child with Down Syndrome. Researchers still have not found a cause to why there is an extra copy of chromosome 21 and have no way of preventing this.

 

3 Types of Down Syndrome

Standard Trisomy 21:

This is the most common type of Down Syndrome (occuring in 95% of all cases of Down Syndrome). The extra copy of chromosome comes from either the mother's egg or the father's sperm, but does not matter which it has come from.

Translocation:

This type of Down Syndrome occurs in 3% of all cases of Down Syndrome. The extra copy of chromosome 21 is "stuck" to another chromosome (usually chromosome 14). The actual act of breaking off from the original position and moving to the different chromosome is called translocation (Homeier, 2005). This type of Down Syndrome can be occassionally inherited.

Mosaic:

This type of Down Syndrome occurs in 2% of all cases. This type of Down Syndrome results in an extra copy of chromosome 21 being found in only some cells, rather than all cells. Proportion of cells that contain the extra copy of chromosome 21 varies greatly from person to person (Routh, 2004).

 

Common Features/Health Issues of those with Down Syndrome

Features on those with Down Syndrome can vary greatly depending on the type of Down Syndrome. The most common features found among those affected by down syndrome are: a lower birth weight and length, small mouth with tongue often sticking out, eyes that slant upwards and outwards, flat faces, and looser muscles and joints. Health issues such as heart defects, hearing loss, poor vision, thyroid disease, leukemia, and diabetes tend to affect those with Down Syndrome at a high rate. Even though these health issues tend to be present, the life expectancy for a person who has Down Syndrome is approximately 55 years.

 

Screening/Testing

While there is no way of knowing why Down Syndrome occurs or how to prevent it, tests that determine whether or not the growing fetus will be affected by Down Syndrome are recommended by doctors for women who are over the age of 35. Blood tests (done between the 15th and 18th weeks of pregnancy) look for hormones that indicate the likelihood for Down Syndrome to be present. Diagnostic tests are only used when there is a high chance of Down Syndrome occurring (diagnostic testing along with amnicentesis have a 2% chance of leading to a miscarriage). A sample of the growing placenta, which is taken out through a long needle, allows doctors to study the fetus' cells to indicate whether or not Down Syndrome is present. Amniocentesis is similar to the diagnostic test, but is a sample of the amniotic fluid rather than the placenta. This also allows doctors to look at fetus' cells to determine whether or not Down Syndrome is present.

 

Closing

Down Syndrome is still a mystery to medical experts. Without knowing what causes this genetic disorder, there is no known way to prevent it. With medical technology advances being made each day, experts are hoping to one day find both a cause and a cure. With Down Syndrome being prevalent within the community and schools, many more organizations are being formed to benefit people with Down Syndrome along with their families.