In some or all of a person's cells, there is an extra copy of chromosome 21, which is known as Down syndrome. Down syndrome is the most common chromosomal disorder and the leading cause of intellectual disability in children. It affects the physical and mental development of the person, causing various health problems and learning difficulties.
Down syndrome can result from any one of three genetic variations:
A person with trisomy 21 has three copies of chromosome 21 in all cells, rather than the typical two copies. This is caused by abnormal cell division during the development of the sperm or egg cell.
The translocation occurs when part of chromosome 21 attaches to another chromosome, usually chromosome 14. In addition to two normal copies of chromosome 21, a person carries extra genetic material from chromosome 21 on another chromosome. This can be inherited from a parent who carries the translocation.
As a result of abnormal cell division after fertilization, some cells have three copies of chromosome 21, while others have two copies.
The exact causes of these genetic variations are not known, but some risk factors include:
Increased maternal age: Women who are older than 35 years have a higher chance of having a child with Down syndrome.
Previous child with Down syndrome: Parents who have had one child with Down syndrome have a slightly increased risk of having another child with the condition.
Genetic translocation: Parents who carry a translocation involving chromosome 21 have an increased risk of passing it on to their children.
Down syndrome affects people in different ways, depending on the type and extent of the genetic variation. However, some common physical features and developmental challenges are:
Flattened face, small head, short neck, and protruding tongue
Upward slanting eyes, small ears, and flat nasal bridge
Poor muscle tone, short stature, and single crease on the palm
Delayed growth, speech, and motor skills
Cognitive impairment, ranging from mild to moderate
Behavioral problems, such as attention deficit, impulsivity, and stubbornness
Medical complications, such as heart defects, gastrointestinal disorders, thyroid problems, hearing loss, vision problems, and increased susceptibility to infections
Down syndrome can be diagnosed before or after birth using various tests:
Prenatal screening tests: These are noninvasive tests that estimate the likelihood of a fetus having Down syndrome based on the mother's age, blood tests, and ultrasound measurements. The results of these tests are not definitive, but they indicate whether further tests are needed.
Prenatal diagnostic tests: These are invasive tests that analyze the fetal chromosomes using samples taken from the placenta (chorionic villus sampling) or amniotic fluid (amniocentesis). Despite the small risk of infection or miscarriage, these tests provide a definitive diagnosis of Down syndrome.
The postnatal tests identify the type and extent of the genetic variation in a newborn by examining its physical features and chromosomes using blood samples or skin cells.
There is no cure for Down syndrome, but early intervention and supportive care can help people with the condition live healthy and fulfilling lives. Some possible treatments include:
Physical therapy: This helps to improve muscle strength, posture, balance, and motor skills.
Speech and language therapy: This helps to enhance communication skills and language development.
Occupational therapy: This helps to adapt everyday tasks and activities to suit the person’s abilities and needs.
Cognitive behavioral therapy: This helps to manage emotional and behavioral issues, such as anxiety, depression, anger, or aggression.
Medications: These may be prescribed to treat specific medical conditions or symptoms associated with Down syndrome, such as thyroid problems, seizures, infections, or sleep apnea.
Surgery: This may be required to correct some physical defects or complications caused by Down syndrome, such as heart defects or gastrointestinal problems.
There is no known way to prevent Down syndrome from occurring. However, some steps that may reduce the risk include:
Having regular prenatal care and screening tests during pregnancy
Avoiding exposure to harmful substances or infections during pregnancy
Seeking genetic counseling if there is a family history of Down syndrome or translocation
Adopting a healthy lifestyle before and during pregnancy
People with Down syndrome have strengths and weaknesses just like everyone else. Down syndrome is neither a disease nor a curse. It is a genetic condition that affects people differently. It is important for families and communities to respect, love, and support them as they learn new skills, make friends, and pursue their dreams.
