By
Dr. Wahied Khawar Balwan
World Down Syndrome Day (WDSD) is an annual March 21 celebration and global awareness day officially observed by the United Nations since 2012. March 21 (3/21) was selected to signify the uniqueness of the triplication (trisomy) of the 21st chromosome which causes Down syndrome. Life expectancy for people with Down syndrome has increased dramatically in recent decades from 25 in 1983 to 60 today. Down syndrome occurs in people of all races and economic levels. People with Down syndrome attend school, work, participate in decisions that affect them, have meaningful relationships, vote and contribute to society in many wonderful ways.
Introduction
Down syndrome is called as it was first observed by John Langdon Down in 1866. Down syndrome is commonest chromosomal disorders affecting both male and female. Down syndrome (or Trisomy 21) is a naturally occurring chromosomal arrangement that has always been a part of the human condition, being universally present across racial, gender or socioeconomic lines in approximately 1 in 600-700 live births, although there is considerable variation worldwide. Down syndrome usually causes varying degrees of intellectual and physical disability and associated medical issues. Down syndrome is a chromosomal condition that occurs when an error in cell division results in an extra chromosome 21. It also increases the likelihood of some health problems. Many factors contribute to Down syndrome, but the prevalence is higher in older pregnant people. There may be a higher chance if a pregnant person is over age 35. A pregnant person at age 25 has about a 1 in 1,250 chance of conceiving a child with Down syndrome. At age 40, the incidence becomes approximately 1 in 100.
There are three types of Down syndrome: trisomy 21 (nondisjunction) accounts for 95% of cases, translocation accounts for about 4%, and mosaicism accounts for about 1%. The incidence of births of children with Down syndrome increases with the age of the mother. But due to higher fertility rates in younger women, 80% of children with Down syndrome are born to women under 35 years of age.
All cells in the body contain genes, which have a specific code or set of instructions for creating the cells. These genes sit inside chromosomes in the cell nucleus. There are typically 46 chromosomes in each cell of these 23 inherited from the mother and 23 from the father. Down syndrome occurs when some or all of a person’s cells have an extra full or partial copy of chromosome 21.
Is Down syndrome Genetic?
In most cases, Down syndrome is not inherited and does not run in families. Though Down syndrome comes from the genes themselves, this is generally due to errors between a sperm and an egg, when the genetic information that forms a child first combines and copies. Down syndrome can have links to genetics. There may be some links between parents of a person with translocation Down syndrome and their likelihood to have more children with Down syndrome in some cases. In parents of a child with Down syndrome due to translocation, there may be an increased chance of Down syndrome in future pregnancies if one of the parents has a genetic rearrangement called a balanced translocation. However, this does not occur in every case of translocation Down syndrome.
Individuals with Down syndrome commonly have distinct physical features, unique health issues, and changes in cognitive development.
Physical Features
Some common physical characteristics / symptoms of Down syndrome can include:
- Eyes that slant upward
- Skin folds on the inner corner of the upper eyelid (Epicanthic fold on eyes)
- White spots on the iris
- Low set Ears
- Constantly opened mouth with protruding tongue
- Low muscle tone
- Flat nasal bridge
- Single, deep creases across the center of the palms called as Simian Crease
- Small hands and feet
- Small Head (Microcephaly)
- Wide gap between Toes
- Clinodactyly
Developmental Delays
People with Down syndrome usually have cognitive development profiles that suggest mild to moderate intellectual disability. However, cognitive development and intellectual ability are highly variable. People with Down syndrome also experience learning difficulties that lead to developmental delays. A person with Down syndrome has a specific pattern of cognitive and behavioral features. These differ from what is seen in typically developing children and children with other causes of intellectual disability.
Children with Down syndrome often reach developmental milestones a little later than their peers. They may be slow to sit, turn over, and stand.
There may also be a delay in coordination and fine motor skills (movements using small muscles in the hands and wrists). These skills can take time to develop after the child acquires gross motor skills, which involve movement of the whole body. Development of speaking and grasping a language may also take longer than expected. With this said, people with Down syndrome eventually meet many of these milestones.
People with Down syndrome may also experience:
- Difficulties with attention
- A tendency to make poor judgments
- Impulsive behavior
With engagement and regular therapy, most people with Down syndrome can attend school and become active members of the community.
Health issues
Sometimes, general health problems can affect any organ system or bodily function. About 40–60% of all people with Down syndrome have a congenital heart defect. There may also be a higher risk of congenital hypothyroidism, Hearing loss, Seizures, Vision disorders such as cataracts and Decreased muscle tone. Children with Down syndrome are also more likely to develop some infections, such as Respiratory infections, Middle ear infections, Tonsillitis and Pneumonia. There seems to be a lower risk of hardening in the arteries, diabetic retinopathy, and most kinds of cancer.
DIAGNOSIS
People with a higher chance of having a child with Down syndrome might receive screening and diagnostic tests. There are two categories of screening tests that doctors can perform. Prenatal screens can estimate the probability of a person having a baby with Down syndrome and justify further tests, but they do not diagnose Down syndrome. Diagnostic tests can definitively tell whether a fetus will have the condition and identify certain abnormalities.
Screening tests cannot confirm whether Down syndrome is present.
Diagnostic tests
Diagnostic tests are more accurate at detecting Down syndrome. A healthcare professional will usually perform such tests inside the uterus. However, diagnostic tests can increase the risk of miscarriage, fetal injury and preterm labor.
Diagnostic tests include:
- Chorionic villus sampling: At 9–11 weeks, a doctor might use a needle inserted into the cervix or the abdomen to take a tiny sample of placenta for analysis.
- Amniocentesis: At 14–18 weeks, a doctor may insert a needle into the abdomen to obtain a small amount of amniotic fluid for analysis.
- Percutaneous umbilical blood sampling: After 20 weeks, the doctor may insert a needle into the abdomen to take a small sample of blood from the umbilical cord for analysis.
A healthcare professional can also diagnose Down syndrome after a baby is born by inspecting their physical characteristics, Blood Lymphocyte Culture and Karyotypy.
TREATMENT
There is no specific treatment for Down syndrome. People who have the condition will receive care for any health problems, as other people do. However, healthcare professionals may recommend additional health screening for issues common to people with the condition.
CONCLUSION
People with Down syndrome attend school, work, participate in decisions that affect them, have meaningful relationships, vote and contribute to society in many wonderful ways. All people with Down syndrome experience cognitive delays, but the effect is usually mild to moderate and is not indicative of the many strengths and talents that each individual possesses. Quality educational programs, a stimulating home environment, good health care and positive support from family, friends and the community enable people with Down syndrome to lead fulfilling and productive lives. People with Down syndrome should always be referred to as people first.
‘Any Error in this Document is silent testimony of the fact that it was a Human Effort’
Dr. Wahied Khawar Balwan
Assistant Professor & Head
Department of Zoology
Govt. Degree College Kilhotran, Doda
E-mail: wahied_kb @yahoo.co.in
Mob. No. 9419369557