Down syndrome is a chromosomal disorder due to an extra copy of chromosome 21, or Trisomy 21. The additional genetic information for development changes results in intellectual disabilities, unique physical characteristics, and some health issues. Down syndrome is among the most prevalent chromosomal disorders, affecting about 1 in every 700 births globally.
Causes of Down Syndrome
– The main reason for Down syndrome is a cell division mistake that leads to an extra chromosome 21. Down syndrome occurs in three forms:
– Trisomy 21 (95%): All the body’s cells have an extra complete copy of chromosome 21 due to faulty cell division.
– Mosaic Down Syndrome (1-2% of the instances): Certain cells possess an excess chromosome 21, whereas some possess the normal 46. This type may show less serious symptoms.
– Translocation Down Syndrome (3-4% of instances): A segment of chromosome 21 is joined to a different chromosome, usually chromosome 14. In some cases, this can be inherited if one parent has a balanced translocation.
Dr. Rajnish Kumar, Principal Director & Unit Head – Neurology, Max Super Speciality Hospital, Dwarka says, “Some things make it more likely that a child will have Down syndrome. The age of the mother is one of these things, with women over 35 more likely to give birth to a baby with the condition. Family history can also play a part, particularly if one of the parents has a translocation type of chromosome 21.”
Symptoms of Down Syndrome
Down syndrome has an array of physical characteristics, development delays, and health issues.
Physical Features: People with Down syndrome tend to have a flat face, short ears, upslanting eyes, a short neck, and small hands with one fold in the palm. They are also likely to have low muscle tone (hypotonia) and loose joints, which limit movement and coordination.
Developmental & Health Issues: According to Dr. Sameer Arora, Senior Consultant – Neurology, Marengo Asia Hospitals Gurugram, “Children with Down syndrome usually have delayed speech and motor development. The majority of them have mild to moderate intellectual disability, but through early intervention, they are able to learn and acquire crucial skills. They are also at increased risk for congenital heart disease, thyroid abnormalities, hearing impairment, and visual impairment. They also carry a higher risk of leukemia, Alzheimer’s disease, and respiratory infection.”
Significance of early diagnosis
Early diagnosis of Down syndrome is necessary to enhance the quality of life of a child. Through an early diagnosis, children can be admitted to intervention programs for cognitive, motor, and social development. Therapy sessions like speech, occupational, and physical therapy can enable individuals to live more independently. Also, routine medical check-ups can enable prompt treatment for related medical conditions.
A number of tests diagnose Down syndrome prenatally and postnatally. Screening tests during pregnancy estimate the risk. The First-Trimester Combined Test involves a blood test and ultrasound for nuchal translucency measurement. NIPT (Non-Invasive Prenatal Testing) tests for fetal DNA in the mother’s blood to find chromosomal defects. If the screening is high risk, diagnostic tests during pregnancy confirm the diagnosis. Chorionic Villus Sampling (CVS), between 10-13 weeks, is a test for placental cells, whereas amniocentesis, which occurs between 15-20 weeks, is a test for amniotic fluid. Both tests are highly reliable but involve a small risk of miscarriage. Postnatally, diagnosis is performed by karyotyping, a blood test that verifies the extra chromosome 21, or the FISH test, which gives quicker results.
Although Down syndrome cannot be cured, medical intervention and therapies enhance quality of life. Routine visits track heart, thyroid, eyesight, and hearing. Physical, occupational, and speech therapy early intervention supports development. Social inclusion and special education enable children to live healthy lives. Parent and caregiver counseling and support through groups are a must.