Down syndrome: growing awareness, expanding support…
For most of us, our genome – the library of chromosomes in each of our cells – contains 23 pairs of chromosomes. These chromosomes are made up of deoxyribonucleic acid (DNA), which contains all of our genetic information.
For some people, chromosome pair number 21 is joined by an extra chromosome due to a congenital condition known as Down syndrome. This extra chromosome causes delays in physical and mental development and certain disabilities.
October is National Down Syndrome Awareness Month in the United States, where it is estimated that one in 700 newborn babies will have Down Syndrome. The global figure is one in 1,000 newborns.
Unfortunately, to date, data regarding Down syndrome in Jordan is limited. Nonetheless, it is believed to be the most common genetic disease in the Kingdom, and increased awareness of the condition can help reduce both cases and stigma.
People with Down syndrome have been featured in art, literature and scientific publications for centuries. However, it was not until 1866 that English physician John Down published a description of the disease. While Down identified the physical characteristics that accompany the disorder according to gender, race and age, it was not until almost a century later that the cause was identified.
How does Down syndrome occur?
All cells in the human body generally contain 46 chromosomes (23 pairs), except for eggs and sperm. These sex cells have only 23 chromosomes but originally derive from a cell with 46.
When a child is conceived, the total 46 chromosomes from egg and sperm combine to form 23 pairs. In some cases, the division of 23 pairs into 23 single chromosomes on a sex cell is incomplete and the cell ends up with 24 chromosomes. This process is known as nondisjunction.
When nondisjunction occurs on the 21st chromosome, it results in Down syndrome. Although this phenomenon can occur with any chromosome, 21 is the most common because an extra chromosome on other pairs after conception often results in miscarriage. Additionally, this mutation can occur at different stages of cell development, resulting in different types of Down syndrome.
The most common type of Down syndrome is known as trisomy 21. This type accounts for about 95% of all cases. Nondisjunction in trisomy 21 occurs before or at the time of conception. The extra chromosome can come from the sperm or the egg; however, it most often originates from the ovum. As the embryo develops, all the cells in its body contain 47 chromosomes.
The second type of Down syndrome is similar to trisomy 21. Nondisjunction occurs after conception and results in a mixture of cells in the body, where some contain 46 chromosomes and some contain 47. This condition is known as mosaicism or mosaic Down syndrome and accounts for about two percent of all cases. People with this type tend to have fewer Down syndrome symptoms than those with trisomy 21.
The best-studied factor regarding the occurrence of Down syndrome is the parents’ age at the time of conception. In fact, nondisjunctional forms of Down syndrome have only been linked to maternal age. …
The last type of Down syndrome is known as translocation Down syndrome. This type of Down syndrome accounts for about three percent of cases. The translocation does not follow the typical nondisjunction mutation. In this form of the disorder, the total number of chromosomes remains at a normal level of 46. However, an extra full or partial copy of chromosome 21 attaches to another chromosome, most commonly chromosome 14, resulting in the typical features of the syndrome. of Down.
Symptoms and Complications
The physical characteristics of Down syndrome are easily recognizable. At birth, the baby is usually of average height and weight, but will develop more slowly than in typical babies. Additionally, the baby will have flat facial features, a smaller head and ears, a short neck with excess skin, upward slant eyes, and poor muscle tone. These physical characteristics are relatively consistent across breeds and genders, but can vary in severity.
Additionally, people with Down syndrome typically suffer from some level of mental and social developmental delays. This can ultimately lead to impulsive behavior, poor judgment, short attention spans, and slow learning abilities. These delays are often mild to moderate, but significant delays can occur in some people.
People with Down syndrome are also prone to some serious health complications, especially related to the cardiovascular system and the immune system. About 50% of people with Down syndrome also have heart defects that can be life-threatening. However, these faults are often repairable.
Likewise, people with Down syndrome are more prone to blood disorders such as leukemia, a type of blood cancer. The disorder is also associated with a weakened immune system, which increases the risk of infections, certain types of cancer, and autoimmune diseases.
Is it avoidable?
Since Down syndrome is a genetic condition, it is not exactly preventable. However, certain factors in parents can increase their likelihood of having a child with this condition.
The best-studied factor regarding the occurrence of Down syndrome is the parents’ age at the time of conception. In fact, non-disjunctive forms of Down syndrome have only been linked to maternal age, no other definitive links can be established with environmental or lifestyle factors. For 20-year-old mothers, the incidence of Down syndrome in children is one in 2,000. By age 30, it rises to one in 350. By age 45, the incidence is about one in 30.
Although maternal age is the most important factor, the occurrence of Down syndrome can also be attributed to the father. Factors related to the paternal side are not well established since these cases represent only 5% of all cases, however, a 2003 study suggested that fathers over 40 are twice as likely to have children with Down’s syndrome.
Also, although it is a genetic condition, Down syndrome is not necessarily hereditary (passed down from parents). Hereditary cases of Down syndrome represent only one percent of the total number of cases and are not related to the nondisjunction varieties, but rather associated with the translocation variety. Even then, only 33% of translocation cases are hereditary.
Since parental age is the biggest concern with Down syndrome, screening might be a helpful measure. This may be especially important for women over 35, men over 40, and those with a family history of Down syndrome.
Is it curable?
Down syndrome is a lifelong incurable disease, but there are a wide variety of programs to help people with Down syndrome and their families. Many support and education programs cover sensory skills, social skills, self-help skills, motor skills, and help with language and cognitive development.
Although development is delayed, education is still just as important for children with Down syndrome. Depending on the severity of their condition and their level of education, some people with Down syndrome may even be able to achieve independence.
In addition, the lifespan of those who suffer from this disease is constantly increasing. Almost a century ago, it was common for a child with Down syndrome to not reach the age of 10. Today, the average life expectancy is 50 to 60 years.
If you are a parent living in Jordan looking for support, consider visiting the Alyasmeen Society for Children with Down Syndrome website at www.yasmeen-jo.com. Alyasmeen’s services include programs to help Jordanians with Down syndrome, and the company also provides information related to the disease.
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