Genetic material is stored in genes. These genes are present in the nucleus of every cell in a Human body. The codes responsible for all of our inherited traits are carried by these genes and these inherited traits are grouped along to rod-like structures called chromosomes. The nucleus of each cell contains 23 pairs of chromosomes. Half of the chromosomes are inherited from each parent. If an individual has a full or partial extra copy of chromosome 21, then he or she tends to have Down syndrome.
Until the nineteenth century, there wasn’t any accurate description of Down syndrome. Later, in 1866, John Langdon Down, an English physician, published an accurate description of a person with Down syndrome. Later he was recognized as the “father” of Down syndrome due to this scholarly work he published.
Down syndrome is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonic) in infancy. Cognitive delays are experienced by affected individuals. It is said to say the intellectual disability is usually mild to moderate. Children with Down syndrome often reach developmental milestones a little later than their peers. For example, there may be a delay in learning to talk. A child may need speech therapy to deal with it. Fine motor skills may also be delayed. They can take time to develop such skills. People with Down syndrome may have a variety of birth defects. About half of all affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the intestine, are also seen in affected persons. There are also high chances for Respiratory problems, Hearing difficulties, Alzheimer’s disease, Childhood Leukemia, Epilepsy, and Thyroid conditions. A few of the common physical traits of Down syndrome are low muscle tone, small stature, an upward slant to the eyes, a single deep crease across the center of the palm a protruding tongue, a large space between the large and second toe and a single flexion furrow of the fifth finger. Although a person with Down syndrome may possess these characteristics to different degrees, or not at all. Every person affected with Down syndrome is totally a unique and different individual.
One in every 700 pregnancies Down syndrome occurs. Research suggests that there is a higher chance if the mother is older than 35 years of age. Down syndrome occurs in less than one in 1000 pregnancies before the age of 30. This figure rises to about 12 in 1,000 after the age of 40. Genetic translocation for Down syndrome on to their children can be transferred through both men and women. Parents who have one child with Down syndrome are at a high risk of having another child with Down syndrome. A genetic counselor can help parents assess the risk of having a second child with Down syndrome.
Down syndrome is generally categorized into 3. They are:
Mosaic Down Syndrome
Translocation Down Syndrome
Down syndrome is caused by trisomy 21 about 95 percent of the time. In such persons, three copies of chromosome 21 will be seen instead of the usual two copies, in all cells. This is caused by abnormal cell division during the development of the sperm cell or the egg cell. This condition is Trisomy 21.
Mosaic Down syndrome is a rare form of Down syndrome. If a person has only some cells with an extra copy of chromosome 21 he or she tends to have Down syndrome. This is caused by abnormal cell division after fertilization.
Translocated Down syndrome happens when a portion of chromosome 21 becomes attached (Translocated) onto another chromosome, before or at conception. These children have the usual two copies of chromosome 21, but they also have additional genetic material from chromosome 21 attached to another chromosome.
Proper screening and diagnostic tests should be followed by people with a higher chance of having a child with Down syndrome Probability of Down syndrome can be estimated through screening tests. Some diagnostic tests can definitively tell whether a baby will have the condition as well. Screening tests include:
Nuchal translucency testing: The clear space in folds of tissue behind the neck of a developing fetus can be measured through an Ultra scan. This is usually done during 11-14 weeks.
Triple screen or quadruple screen: The quantities of various substances in the mother’s blood can be measured through this screening test. This is usually done during 15-18 weeks.
Integrated screen: This combines results from first-trimester blood and screening tests, with or without nuchal translucency, with second-trimester quadruple screening results.
Cell-free DNA: The fetal DNA present in the mother’s blood is analyzed through this Blood test.
Genetic ultrasound: At 18–20 weeks, doctors combine a detailed ultrasound with blood test results.
Screening is a cost-effective and less invasive way to determine Down syndrome. A few Diagnostic tests are also inevitable in detecting Down syndrome.
Diagnostic tests include:
Chorionic villus sampling: Using a needle inserted into the cervix or the abdomen the doctor takes a tiny sample of the placenta. This test is performed on this sample during 8-12 weeks.
Amniocentesis: Using a needle inserted into the abdomen the doctor obtains a small amount of amniotic fluid. This test is performed on this sample during 15-20 weeks.
Percutaneous umbilical blood sampling: Using a needle inserted into the abdomen the doctor takes a small sample of blood from the umbilical cord. This sample is analyzed after 20 weeks.
There is no specific treatment for Down syndrome. People who have the condition must be given good care always. Early intervention can help a person maximize their potential and prepare them to take up an active role in the community. It is said prevention is better than cure. Hence, Prenatal screening tests are a must do for every Pregnant woman. So, let’s build a future without Down syndrome.