Down Syndrome also known as Trisomy 21 is a genetic condition caused by the presence of an extra copy of chromosome 21. It is one of the most common genetic disorders affecting both children and adults worldwide. World Down Syndrome Day aims to raise awareness about the condition and ways to manage it.
Understanding Down Syndrome
Usually, humans have 23 pairs of chromosomes; one set from each parent. People with Down's syndrome have the same genes as anyone else; they just have 1 extra. This extra copy of chromosome 21 results in a total of 47 chromosomes instead of the usual 46. The presence of this additional chromosome disrupts the normal balance of genetic information in the body leading to intellectual and developmental delays.
People with Down Syndrome generally share certain physical traits such as a flat facial profile, almond-shaped eyes, small ears and a single deep crease across the palm. While these characteristics are common, the severity of the condition and the specific traits can vary widely among individuals. In addition to physical features, children with Down Syndrome often experience developmental delays including speech and motor skill delays as well as cognitive challenges.
Causes of Down Syndrome
The majority of Down Syndrome cases (approximately 95%) are caused by a genetic anomaly that occurs during the formation of egg or sperm cells. This error leads to an extra copy of chromosome 21 being passed on to the child. Less common forms of Down Syndrome include instances where a part of chromosome 21 detaches and attaches to another chromosome or a rare type known as mosaic Down Syndrome, where some cells have the usual two copies of chromosome 21, while others contain three copies, resulting in a milder version of the condition.
Early Diagnosis and Lab Tests
Early diagnosis plays an important role in improving the long-term outlook for children with Down Syndrome. In India, prenatal screening and diagnostic tests can help identify the risk of the condition. Dr Jasmin Surana, MD Biochemistry and Consultant Biochemist at Metropolis Healthcare Ltd shares lab tests one can undergo for early diagnosis.
First Trimester Screening (FTS): This test is done between the 11th and 14th weeks of pregnancy. It combines a blood test to measure certain proteins and an ultrasound to assess nuchal translucency, a fluid-filled space at the back of the baby’s neck. The results provide an estimate of the likelihood of the baby having Down Syndrome.
Non-Invasive Prenatal Testing (NIPT): This highly accurate test analyzes the fetal DNA found in the mother’s blood. NIPT can detect Down Syndrome and other chromosomal abnormalities and can be done as early as 10 weeks of pregnancy.
Diagnostic Tests (Amniocentesis and Chorionic Villus Sampling - CVS): These invasive tests provide definitive results. Amniocentesis is typically done between the 15th and 20th weeks, while CVS can be performed earlier, between the 10th and 13th weeks. Although both tests carry a small risk of miscarriage, they can confirm the presence of Down Syndrome.
In addition to prenatal screening, post-birth diagnoses can be made through genetic testing to confirm the presence of an extra chromosome 21.
Prevention and Management
Currently, there is no way to prevent Down Syndrome since it results from a random genetic error during conception. However, early detection through prenatal screening and diagnostic tests can provide valuable information for parents, enabling them to make informed decisions during pregnancy. Maintaining maternal health and avoiding risk factors such as smoking or substance abuse can help ensure better pregnancy outcomes.
The management of patients with Down syndrome requires a collaborative, team-based approach. The family is referred to a clinical geneticist for genetic testing and counselling for both parents. Since Down syndrome can affect nearly every organ system, it is essential for the child to be evaluated by a range of specialists including an eye specialist, orthopaedic surgeon, cardiologist, dermatologist, gastroenterologist, physical therapist, behaviour expert, ENT specialist and mental health professional.
ALSO READ: National Anaemia Day: Why women are more anaemic? 5 ways to address it