World Down Syndrome Day by Sereena Herman

 

What is Down Syndrome?

 The genetic material for plants and animals can be found in the chromosomes, which are located in the nucleus of cells present in these organisms. During the process of reproduction these chromosomes are vital in the creation of the next generation. Usually, at birth a baby is born with 23 pairs of chromosomes, with 23 being from the mother and 23 from the father. Down syndrome also known as Trisomy 21 is a genetic condition where a person has a partial or extra pair of chromosomes which is referred to a trisomy. This specifically affects chromosome 21 as a result of abnormal cell division. This extra pair of genes results in a variety of physical and cognitive developmental issues in children born with Down syndrome. According to the Jamaica Down’s Syndrome Foundation, 1 in every 868 babies born in Jamaica are affected by Down Syndrome. Globally the UN reports that the estimated incidence of Down syndrome is approximately 1 in every 1000-1100 live births.

What are the symptoms of Down Syndrome?

The symptoms of down syndrome vary from person to person and as such the severity of symptoms may range from mild to severe with each person. The main physical symptoms of Down Syndrome are as follows:

Flattened face

Small head

Short neck 

Protruding tongue 

Poor muscle tone 

Loose joints

Almond shaped eyes that usually slant upwards

Small hands and feet

Single line across the palm

Shorter height than normal is also observed in children and adults.

In addition to these physical symptoms many persons who have down syndrome, may speak slower than other children, may possess an IQ that is classified in the low to moderate range and their short-term and long-term memory may also be affected. Although many persons who are diagnosed with this condition suffer from no other genetical disease, birth defects or health problems, some do. For those who do suffer from other health conditions, the following are most often presented: hearing loss, ear infections, eye infections, heart defects and so on.

What are the different types of Down Syndrome?

There are three main type of Down Syndrome, Trisomy 21 otherwise known as Non-disjunction, Mosaicism and Translocation Down Syndrome.

Non-Disjunction (Trisomy 21) Down Syndrome: This is the most common type of Down Syndrome as it affects approximately 95% of people diagnosed with Down Syndrome. It occurs when there are three copies of chromosome 21 in each cell instead of the usual pair or two copies.

Translocation Down Syndrome: This form accounts for approximately 4% of all Down Syndrome cases and occurs when an extra chromosome 21 or a portion of it is present. It differs from Trisomy 21 as this extra chromosome is not separate but is instead attached to another chromosome.

Mosaicism: This accounts for the least number of Down Syndrome cases as only approximately 1 to 2% of persons who are affected by the condition suffer from this form. This form consists of a combination of Trisomy 21 and the usual two copies of chromosome 21 distributed throughout the cells of the body. Persons with this form of down syndrome will still present with the symptoms of Down Syndrome, however due to some or many of the cells having a normal genetic makeup, these individuals will present with fewer features of the condition.

Risk Factors

       The main risk factor for Down Syndrome is maternal age as the risk of having a child with Down syndrome increases greatly over the age of 35 years. Despite this, according to the National Down Syndrome Society (NDSS) approximately 80% of all children who are born with Down Syndrome are born to mothers who are below 35 years or age due to the great number of births by mothers in that group. 

       Secondly, parents who are carriers of the Translocation gene for Down Syndrome have a higher risk of having a child with the condition. Additionally, for parents who already have a child with Down Syndrome are at increased risk of having another child with Down Syndrome.

Screening and Diagnosis 

Down Syndrome is usually detected during pregnancy via screening and diagnostic tests. Screening tests are used to ascertain the chance of a pregnancy having Down Syndrome, but are not final while diagnostic tests are used to identify or detect the possible presence of Down Syndrome in the baby but it poses a greater risk for the developing baby and the mother. 

Screening tests often include various blood tests that monitor and pick up various substances present in the mother’s blood which could indicate the risk of the condition in the baby. One such test is the Maternal Serum Alpha-fetoprotein (MS-AFP) which indicates the possibility for either a neural tube defect or chromosomal abnormality when the test result is positive. Additionally, ultrasounds are conducted where technicians scan for extra fluid behind the neck of the baby which may indicate a genetically problem. 

Diagnostic tests are usually only performed after a positive screening test due to the increased risk, and There are many diagnostic tests available however three main tests that are used include Amniocentesis where the amniotic fluid is examined to identify any abnormalities, the Chorionic villus sampling (CVS) which focuses on the placenta and examines material obtained from it, and the Percutaneous umbilical blood sampling (PUBS) which uses blood from the umbilical cord to identify any possible abnormalities. 

Treatment

Down Syndrome is a condition that lasts for a lifetime, however treatment options are available especially for babies and young children in order to help then to improve their cognitive abilities as well as to adapt and overcome their physical challenges. There are many services available to individuals with Down Syndrome with the aim of improving their quality of life. Such services include physical therapy, speech therapy, occupational therapy among others which are usually introduced as an early intervention measure. With adequate support many children with Down Syndrome can be included in regular classes but additional help and attention may also be needed. Overall persons who suffer from Down Syndrome can successfully function in society when provided with the proper tools and support that they need.

_________________________________________

Note: Sorry, this should have been posted on March 21, 2022,World Syndrome Day.

References

Alpha-Fetoprotein (AFP) Test: MedlinePlus Lab Test Information. (2020, July 30). Medlineplus.gov. https://medlineplus.gov/lab-tests/alpha-fetoprotein-afp-test/

Centers for Disease Control and Prevention. (2021, April 6). Facts about down syndrome. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html

Mayo Clinic. (2018, March 8). Down Syndrome - Symptoms and Causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/down-syndrome/symptoms-causes/syc-20355977

National Down Syndrome Society. (2017). What is Down syndrome? NDSS. https://www.ndss.org/about-down-syndrome/down-syndrome/

Nations, U. (2021, March 21). World Down Syndrome Day. United Nations. https://www.un.org/en/observances/down-syndrome-day#:~:text=The%20estimated%20incidence%20of%20Down